tag:theconversation.com,2011:/au/topics/weather-forecasting-3218/articlesWeather forecasting – The Conversation2024-03-11T10:04:45Ztag:theconversation.com,2011:article/2185452024-03-11T10:04:45Z2024-03-11T10:04:45ZEast Africa must prepare for more extreme rainfall during the short rainy season – new study<p>East Africa has recently had an <a href="https://earthobservatory.nasa.gov/images/150712/worst-drought-on-record-parches-horn-of-africa">unprecedented series of failed rains</a>. But some rainy seasons are bringing the opposite: huge amounts of rainfall. </p>
<p>In the last few months of 2023, the rainy season, known as the “short rains”, was much wetter than normal. It brought severe flooding to Kenya, Somalia and Tanzania. In Somalia, <a href="https://news.un.org/en/story/2023/11/1144202">more than</a> 2 million people were affected, with over 100 killed and 750,000 displaced from their homes. Tens of thousands of people in northern Kenya <a href="https://www.euronews.com/green/2023/12/15/floods-have-washed-away-entire-villages-kenyas-rains-made-twice-as-intense-by-climate-chan">lost</a> livestock, farmland and homes. </p>
<p>The very wet short rainy seasons are linked to a climate event known as a positive Indian Ocean Dipole (known as the “IOD”). And climate model projections <a href="https://www.nature.com/articles/s41558-020-00943-1">show an increasing trend</a> of extreme Indian Ocean dipoles. </p>
<p>In a <a href="https://doi.org/10.1029/2023GL105258">new research paper</a>, we set out to investigate what effect more frequent extreme Indian Ocean Dipole events would have on rainfall in east Africa. We did this using a large number of climate simulations and models.</p>
<p>Our results show that they increase the likelihood of very wet days – therefore making very wet seasons. </p>
<p>This could lead to extreme weather events, even more extreme than the floods of 1997, which led to <a href="https://www.fao.org/3/w7832e/w7832e00.htm">10 million people requiring emergency assistance</a>, or those of 2019, when <a href="https://fews.net/east-africa/special-report/january-2020">hundreds of thousands were displaced</a>.</p>
<p>We recommend that decision-makers plan for this kind of extreme rainfall, and the resulting devastating floods.</p>
<h2>How the Indian Ocean Dipole works</h2>
<p>Indian Ocean Dipole events tend to occur in the second half of the year, and can last for months. They have two phases: positive and negative. </p>
<p>Positive events occur when the temperature of the sea surface in the western Indian Ocean is warmer than normal and the temperature in the eastern Indian Ocean is cooler than normal. Put simply, this temperature difference <a href="https://www.nature.com/articles/43854">happens when</a> winds move warmer water away from the ocean surface in the eastern region, allowing cooler water to rise. </p>
<p>In the warmer western Indian Ocean, more heated air will rise, along with water vapour. This forms clouds, bringing rain. Meanwhile, the eastern part of the Indian Ocean will be cooler and drier. This is why flooding in east Africa can happen at the same time as <a href="https://theconversation.com/indian-ocean-linked-to-bushfires-and-drought-in-australia-20893">bushfires in Australia</a>.</p>
<p>The opposite is true for negative dipole events: drier in the western Indian Ocean and wetter in the east. </p>
<p>Under climate change we’re expecting to see more frequent and more extreme positive dipole events – bigger differences between east and west. This is <a href="https://www.carbonbrief.org/guest-post-why-climate-change-will-cause-more-strong-indian-ocean-dipole-events/">shown by climate model projections</a>. They are believed to be driven by different paces of warming across the tropical Indian Ocean – with western and northern regions projected to warm faster than eastern parts.</p>
<p>Often heavy rain seasons in east Africa are attributed to El Niño, but <a href="https://rmets.onlinelibrary.wiley.com/doi/10.1002/asl.1015">recent research</a> has shown that the direct impact of El Niño on east African rainfall is actually relatively modest. El Niño’s principal influence lies in its capacity to bring about positive dipole events. This occurs since El Niño events tend to cool the water in the western Pacific Ocean – around Indonesia – which also helps to cool down the water in the eastern Indian Ocean. These cooler temperatures then help kick-start a positive Indian Ocean Dipole.</p>
<h2>Examining unprecedented events</h2>
<p>Extreme positive Indian Ocean Dipole events are rare in the recent climate record. So to examine their potential impacts on rainfall extremes, we used a large set of climate simulations. The data allowed us to diagnose the sensitivity of rainfall to larger Indian Ocean Dipole events in a statistically robust way.</p>
<p>Our results show that as positive dipole events become more extreme, more wet days during the short rains season can be expected. This effect was found to be largest for the frequency of extremely wet days. Additionally, we found that as the dipole strength increases, the influence on the most extreme days becomes even larger. This means that dipole events which are even slightly “record-breaking” could lead to unprecedented levels of seasonal rainfall. </p>
<p>Ultimately, if positive Indian Ocean Dipole seasons increase in frequency, as predicted, regular seasons of flooding impacts will become a new normal.</p>
<p>One aspect not included in our analysis is the influence of a warmer atmosphere on rainfall extremes. A warmer atmosphere <a href="https://www.carbonbrief.org/explainer-what-climate-models-tell-us-about-future-rainfall/">holds more moisture</a>, allowing for the development of more intense rain storms. This effect could combine with the influence of extreme positive dipoles to bring unprecedented levels of rainfall to the Horn of Africa. </p>
<p>2023 was <a href="https://wmo.int/media/news/wmo-confirms-2023-smashes-global-temperature-record">a year of record-breaking temperatures driven both by El Niño and global warming</a>. We might expect that this warmer air could have intensified rain storms during the season. Indeed, evidence from <a href="https://www.worldweatherattribution.org/climate-change-indian-ocean-dipole-compounding-natural-hazards-and-high-vulnerability-increased-severity-of-flooding-in-the-horn-of-africa/">a recent assessment</a> suggests that climate change-driven warming is highly likely responsible for increased rainfall totals. </p>
<h2>Responding to an unprecedented future</h2>
<p>Policymakers need to plan for this. </p>
<p>In the long term it is crucial to ensure that any new infrastructure is robust to withstand more frequent and heavier rains, and that government, development and humanitarian actors have the capacity to respond to the challenges.</p>
<p>Better use of technology, such as innovations in <a href="https://fastaweather.com/">disseminating satellite rainfall monitoring via mobile phones</a>, can communicate immediate risk. <a href="https://www.science.org/content/article/ai-churns-out-lightning-fast-forecasts-good-weather-agencies">New frontiers in AI-based weather prediction</a> could improve the ability to anticipate localised rain storms, including <a href="https://www.wfp.org/publications/2023-machine-learning-early-warning-systems">initiatives focusing on eastern Africa</a> specifically. </p>
<p><a href="https://www.youtube.com/watch?v=9g_06jBU-ag">Linking rainfall information with hydrological models designed for dryland environments</a> is also essential. These will help to translate weather forecasts into impact forecasts, such as identifying risks of flash flooding down normally dry channels or bank overflow of key rivers in drylands.</p>
<p>These technological improvements are crucial. But better use of the forecast information we already have can also make a big difference. For instance, initiatives like <a href="https://www.climatecentre.org/priority_areas/fbf-ibf/">“forecast-based financing”</a>, pioneered by the Red Cross Red Crescent movement, link forecast triggers to pre-approved financing and predefined action plans, helping communities protect themselves before hazards have even started.</p>
<p>For these endeavours to succeed, there must be dialogue between the science and practitioner communities. The scientific community can work with practitioners to integrate key insights into decisions, while practitioners can help to ensure research efforts target critical needs. With this, we can effectively build resilience to natural hazards and resist the increasing risks of our changing climate.</p><img src="https://counter.theconversation.com/content/218545/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Erik W. Kolstad receives funding from the European Union’s Horizon 2020 programme through the CONFER project (grant 869730)</span></em></p><p class="fine-print"><em><span>Katerina Michaelides receives funding from EU H2020, the FCDO and the Leverhulme Trust. </span></em></p><p class="fine-print"><em><span>Michael Singer receives funding from the European Union's Horizon 2020 Programme. </span></em></p><p class="fine-print"><em><span>David MacLeod does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Projections show that there’ll be Indian Ocean dipoles in the future – and that means more rainy days, and more extreme rainfall.David MacLeod, Lecturer in Climate Risk, Cardiff UniversityErik W. Kolstad, Research professor, Uni ResearchKaterina Michaelides, Professor of Dryland Hydrology, School of Geographical Sciences, University of BristolMichael Singer, Professor of Hydrology and Geomorphology, Cardiff UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2165622023-10-30T16:58:07Z2023-10-30T16:58:07ZExtreme weather is outpacing even the worst-case scenarios of our forecasting models<p>In the wake of the destructive Hurricane Otis, we find ourselves at a pivotal moment in the history of weather forecasting. The hurricane roared ashore with 165mph winds and torrential rainfall, slamming into the coastal city of Acapulco, Mexico and claiming the lives of <a href="https://apnews.com/article/mexico-hurricane-otis-acapulco-50eb6a8fe677455428cbacfd3966e72c">at least 48 people</a>. </p>
<p>The speed at which Otis intensified was unprecedented. Within 12 hours it went from a regular tropical storm to a “category 5” hurricane, the most powerful category and one which might occur only a few times worldwide each year. </p>
<p>This rare and alarming event, described by the US National Hurricane Center as a “<a href="https://www.nhc.noaa.gov/archive/2023/ep18/ep182023.discus.012.shtml">nightmare scenario</a>”, broke records for the fastest intensification rate over a 12-hour period in the eastern Pacific. Otis not only caught residents and authorities off guard but also exposed the limitations of our current predictive tools.</p>
<p>I specialise in <a href="https://uel.ac.uk/about-uel/staff/ravindra-jayaratne">the study of natural disasters</a> with the goal of improving our ability to predict them and ultimately to save lives. It is critical that we address the pressing concerns related to the tools we use for forecasting these catastrophic events, all while recognising the significant influence of rapid climate change on our forecasting capabilities.</p>
<h2>The predictive tools we rely on</h2>
<p>At the core of weather forecasting are computer programs, or “models”, that blend atmospheric variables such as temperature, humidity, wind and pressure, with fundamental physics. </p>
<p>Since the atmospheric processes are nonlinear, a small degree of uncertainty in initial atmospheric conditions can lead to a large discrepancy in final forecasts. That’s why the general practice now is to forecast a set of possible scenarios rather than predict the single scenario most likely to occur.</p>
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<span class="caption">Hurricane Otis reaches its maximum intensity just as it hits Acapulco on October 25.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Otis_2023-10-25_0300Z.jpg">ABI / NOAA GOES-16 / wiki</a></span>
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<p>But while these models are instrumental in issuing early warnings and evacuation orders, they have fundamental limitations and carry a significant degree of uncertainty, especially when dealing with rare or extreme weather. This uncertainty arises from various factors including the <a href="https://royalsocietypublishing.org/doi/10.1098/rsta.2011.0161">fundamentally chaotic nature of the system</a>.</p>
<p>First, the historical data is incomplete, since a hurricane such as Otis might occur only once in several millennia. We don’t know when an east Pacific storm last turned into a category 5 hurricane overnight – if ever – but it was certainly before modern satellites and weather buoys. Our models struggle to account for these “one in 1,000-year events” because we simply haven’t observed them before.</p>
<p>The complex physics governing the weather also has to be simplified in these predictive models. While this approach is effective for common scenarios, it falls short when dealing with the intricacies of extreme events that involve rare combinations of variables and factors.</p>
<p>And then there are the unknown unknowns: factors our models cannot account for because we are unaware of them, or they have not been integrated into our predictive frameworks. Unanticipated interactions among various climatic drivers can lead to unprecedented intensification, as was the case with Hurricane Otis. </p>
<h2>The role of climate change</h2>
<p>To all this we can add the problem of climate change and its impact on extreme weather. Hurricanes, in particular, are influenced by rising sea surface temperatures, which provides more energy for storms to form and intensify. </p>
<p>The connection between climate change and the intensification of hurricanes, coupled with other factors such as high precipitation or high tides, is <a href="https://www.nature.com/articles/s41467-023-40605-2">becoming clearer</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1717644354624299402"}"></div></p>
<p>With established weather patterns being altered, it is becoming even more challenging to predict the behaviour of storms and their intensification. Historical data may no longer serve as a reliable guide.</p>
<h2>The way forward</h2>
<p>The challenges are formidable but not insurmountable. There are a few steps we can take to enhance our forecasting and better prepare for the uncertainties that lie ahead.</p>
<p>The first would be to develop more advanced predictive models that integrate a broader range of factors and variables, as well as consider worst-case scenarios. Artificial intelligence and machine learning tools can help us process vast and complex datasets more efficiently. </p>
<p>But to get this additional data we’ll have to invest in more weather monitoring stations, satellite technology, AI tools and atmospheric and oceanographic research. </p>
<p>Since even world experts and their models can be caught out by sudden weather extremes, we also need to educate the public about the limitations and uncertainties in weather forecasting. </p>
<p>We must encourage preparedness and a proactive response to warnings, even when predictions seem uncertain. And of course we still have to mitigate climate change itself: the root cause of intensifying weather events. </p>
<p>Hurricane Otis provided a stark and immediate reminder of the inadequacies of our current predictive tools in the face of rapid climate change and increasingly extreme weather events. The urgency to adapt and innovate in the realm of weather forecasting has never been greater. </p>
<p>It is incumbent upon us to rise to the occasion and usher in a new era of prediction that can keep pace with the ever-shifting dynamics of our planet’s climate. Our future depends on it.</p>
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<p class="fine-print"><em><span>Ravindra Jayaratne does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A deadly hurricane developed in just 12 hours.Ravindra Jayaratne, Reader in Coastal Engineering, University of East LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2110152023-10-24T14:59:03Z2023-10-24T14:59:03ZRoyal Charter storm of 1859: how an almighty tempest led to the birth of the UK’s shipping forecast<figure><img src="https://images.theconversation.com/files/551692/original/file-20231003-27-6msxku.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1000%2C633&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Royal Charter was shipwrecked at Porth Alerth near Moelfre on Anglesey. </span> <span class="attribution"><span class="source">John Oxley Library, State Library of Queensland</span></span></figcaption></figure><p><em>You can read this article in <a href="https://theconversation.com/storm-y-royal-charter-1859-a-chreur-rhagolygon-tywydd-i-forwyr-215368">Welsh</a></em>.</p>
<p>In British weather history, one storm stands out as a catalyst for change – the Royal Charter Storm of 1859. This devastating tempest off the west coast of Britain played a pivotal role in the founding of the shipping forecast and has had an enduring <a href="https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/j.1477-8696.1970.tb04108.x">impact</a> on weather forecasting in the UK and beyond. </p>
<p>Winds gusted at 100 miles per hour between October 25 and 26 that year – <a href="https://royalsocietypublishing.org/doi/10.1098/rspl.1859.0047">higher</a> than any previously recorded in the Mersey, in north-west England. And it’s considered to be the <a href="https://www.metoffice.gov.uk/about-us/who/our-history/the-royal-charter-gale">most severe</a> Irish Sea storm of the 19th century. More than 800 lives were lost and the storm sank or badly damaged more than 200 ships. But it also paved the way for the creation of the shipping forecast. </p>
<p>The storm is named after the most famous of the ships lost to the waves, a steam and sailing ship called the <a href="https://blog.library.wales/a-helpless-ruin-on-the-shores-of-anglesea-the-royal-charter-and-the-rothsay-castle-shipwrecks/">Royal Charter</a>. After a two-month journey from Melbourne in Australia, the Royal Charter was heading towards Liverpool with its valuable cargo of gold. The ship was caught in the full fury of the storm off the coast of Anglesey, Wales. </p>
<p>Despite the crew’s valiant efforts to anchor the ship and cut its sails, the Royal Charter was driven onto the rocks in the early hours of October 26. With the help of villagers onshore, they succeeded in saving around 40 passengers. Other passengers had tried to swim to shore but were weighed down by the gold in their pockets and drowned. The ship eventually split in two and the waves claimed the lives of more than 450 passengers and crew members, including all the women and children aboard. </p>
<p>The tragic loss of life and property made the storm headline news. It even came to the attention of <a href="https://books.google.co.uk/books/about/Shipwreck.html?id=oV_XAAAACAAJ&redir_esc=y">Charles Dickens</a>, who was working as a journalist in London at the time and visited the site of the wreck soon after the storm. </p>
<h2>The shipping forecast and the Met Office</h2>
<p>Weather observations had been collected from around the British coast <a href="https://www.metoffice.gov.uk/research/library-and-archive/archive-hidden-treasures/met-office-history">since 1854</a> by a part of the UK Met Office known then as the Meteorological Department of the Board of Trade. The Royal Charter Storm, however, highlighted a need for more accurate weather forecasting and a national storm warning system. </p>
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<img alt="An old black and white photo of a man in a tailcoat" src="https://images.theconversation.com/files/551757/original/file-20231003-27-52l57b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551757/original/file-20231003-27-52l57b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=998&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551757/original/file-20231003-27-52l57b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=998&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551757/original/file-20231003-27-52l57b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=998&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551757/original/file-20231003-27-52l57b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1254&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551757/original/file-20231003-27-52l57b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1254&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551757/original/file-20231003-27-52l57b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1254&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Vice Admiral Robert Fitzroy.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:FitzRoy.jpg?uselang=en#/media/File:FitzRoy.jpg">Wikimedia Commons</a></span>
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<p>Vice Admiral <a href="https://www.britannica.com/biography/Robert-Fitzroy">Robert Fitzroy</a>, founder of the Met Office, had been lobbying for the creation of such a storm warning system since the summer of 1859. Following the Royal Charter storm, Fitzroy was able to <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rspl.1859.0111">demonstrate</a> that it could have been predicted. </p>
<p>In December of that year, the new storm warning system was approved and the first warning was issued in February 1861. This was delivered by telegraph to harbour towns, who then hoisted cones and drums on a mast to warn vessels in harbours and along the coast of the incoming storm.</p>
<p>The UK’s storm warning service – which later became known as the <a href="https://www.bbc.co.uk/programmes/b006qfvv">shipping forecast</a> – is the longest running national forecasting service in the world. Today, the Met Office <a href="https://www.metoffice.gov.uk/weather/specialist-forecasts/coast-and-sea/shipping-forecast">provides</a> the shipping forecast on behalf of the Maritime and Coastguard Agency, and issues a forecast four times a day for the 31 areas of sea around the British Isles.</p>
<h2>A lasting legacy</h2>
<p>In addition to its <a href="https://press.uchicago.edu/ucp/books/book/chicago/P/bo3534836.html">meteorological legacy</a>, the effects of the storm can still be seen around the Welsh coastline to this day. On Anglesey, the <a href="https://www.peoplescollection.wales/items/44470">graves</a> of those who died in the wreck can be found in many churches along the coast. Gold nuggets have also <a href="https://www.walesonline.co.uk/news/wales-news/gold-nugget-worth-50000-washed-11311063">washed ashore</a> in recent years.</p>
<p>Further south, in Cwmyreglwys, Pembrokeshire, stand the remains of Saint Brynach’s church, which was partially destroyed by the storm.</p>
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<img alt="One stone wall of a church stands on a beautiful coastline." src="https://images.theconversation.com/files/551794/original/file-20231003-19-2458g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551794/original/file-20231003-19-2458g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551794/original/file-20231003-19-2458g6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551794/original/file-20231003-19-2458g6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551794/original/file-20231003-19-2458g6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551794/original/file-20231003-19-2458g6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551794/original/file-20231003-19-2458g6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The ruins of St Brynach’s Church in Cwmyreglwys, Pembrokeshire.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/st-brynachs-church-cwm-yr-eglwys-141734476">Dr Morley Read/Shutterstock</a></span>
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<p><a href="https://www.metoffice.gov.uk/about-us/who/our-history">Since 1859</a>, the Met Office has made <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/met-office-and-forecasting-firsts/met-office-and-forecasting-firsts">significant strides</a> in the field of meteorology. In August 1861, the first public <a href="https://www.bbc.co.uk/news/av/uk-14361204">weather forecast</a> was printed in The Times, then broadcast on the radio in 1922 and was eventually seen on television for the first time in 1936. </p>
<p>Step by step, the Met Office has pioneered new technologies by launching the world’s first meteorological satellite in 1960 and using the first forecast by a computer in 1965. It has continued to invest in state-of-the-art <a href="https://www.metoffice.gov.uk/about-us/what/technology/supercomputer">supercomputers</a> to improve severe weather and climate forecasting since then.</p>
<p>Today, the Met Office is a globally recognised authority in meteorology and climate science. Its expertise is invaluable for numerous sectors, from aviation and agriculture to emergency services and infrastructure planning. The Met Office is now responsible for providing the <a href="https://www.metoffice.gov.uk/weather/warnings-and-advice">National Severe Weather Warning Service</a>, which includes warnings for wind, rain, thunderstorms, lightning, ice, fog, snow and extreme heat.</p>
<p>Through the Met Office’s dedication to scientific research and accurate forecasting, the UK and the world have benefited from improved weather predictions and increased preparedness for extreme weather events. The legacy of the Royal Charter Storm lives on in the Met Office’s ongoing mission to provide essential weather and climate services, safeguarding lives and livelihoods in an ever-changing climate.</p><img src="https://counter.theconversation.com/content/211015/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cerys Jones has previously received funding from the AHRC, EU's Ireland-Wales Programme 2014-2020, and the Coleg Cymraeg Cenedlaethol.</span></em></p>More than 800 lives were lost in the Royal Charter storm but it also led to improvements in weather forecasting.Cerys Jones, Geography Lecturer, Aberystwyth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2138772023-09-19T11:52:50Z2023-09-19T11:52:50ZSouth Africa’s destructive storm surges: geoscientist reveals the 3 factors that drove them<figure><img src="https://images.theconversation.com/files/549052/original/file-20230919-27-26ykei.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tidal surges can cause enormous damage.</span> <span class="attribution"><span class="source">Martha van der Westhuizen/500px</span></span></figcaption></figure><p><em>A series of powerful tidal surges <a href="https://www.news24.com/news24/southafrica/news/battered-coastal-areas-begin-mop-up-operations-after-spring-tide-damage-20230918">battered</a> coastal areas in South Africa’s Western Cape, Eastern Cape and KwaZulu-Natal provinces over the weekend of 16 September. <a href="https://www.news24.com/news24/southafrica/news/spring-tide-damage-woman-dies-after-waves-crash-into-george-car-park-another-dangerous-surge-expected-20230917">One person died</a>; cars, homes and businesses were damaged. The Conversation Africa asked Jasper Knight, a geoscientist who researches coastal processes, to explain what happened.</em></p>
<h2>What drove the flooding?</h2>
<p>A critical combination of three factors resulted in this significant flooding. First, a storm surge associated with low-pressure weather systems coming onshore. These happen very commonly but often don’t result in high amounts of flooding by themselves. </p>
<p>Second, low-pressure cells often result in strong onshore winds, and these can whip up the sea surface and create big waves which can potentially run further inland, especially when the sea surface is raised.</p>
<p>Third, the coincidence of the storm with the period of high tide (a monthly event) and equinoctial high-high tide (a seasonal event). It is this combination that is the cause here, not these individual factors in isolation.</p>
<h2>What is a storm surge?</h2>
<p>This is where the level of the sea surface near the coast is temporarily raised up and results in flooding along that coastal stretch. Storm surges are caused by a low pressure (cyclone) weather system approaching the coastline from the ocean. Low pressure causes the sea surface to bulge upwards below the centre or eye of the cyclone, and the magnitude of this disturbance is related to the severity of the low pressure system – the deeper the low pressure cell, the higher the elevation of the sea surface. This is usually on the order of tens of centimetres to one metre or so. </p>
<p>As the cyclone approaches land, the water surface along the coast rises.</p>
<h2>What is a spring tide?</h2>
<p>Despite their name, <a href="https://oceanservice.noaa.gov/facts/springtide.html">spring tides</a> are regular occurrences throughout the year. They take place when the sun, Earth and moon are in alignment, and this happens once every (lunar) month. In addition, there are also times of the year, around the <a href="https://education.nationalgeographic.org/resource/equinox/">equinoxes</a>, where spring tides are higher than average. </p>
<p>We are very near the spring (vernal) equinox in the southern hemisphere (which is on or about 22 September). This is a period when the sun is aligned overhead of Earth’s equator and so exerts a bigger tidal force on the oceans. This may have been a contributing factor to the higher water levels around the coast.</p>
<h2>Were people sufficiently warned?</h2>
<p>Tidal patterns are highly predictable and this data is widely available for ports or harbours along the coast. In this case, the South African Weather Service issued <a href="https://www.news24.com/news24/southafrica/news/saturdays-weather-damaging-winds-waves-and-a-storm-surge-warning-for-the-coast-20230915">a warning</a>. This information is particularly useful for boaters, fishermen and other coastal users. Weather patterns are also fairly predictable, which is what weather forecasting is all about, so we know when a big storm may be approaching. </p>
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Read more:
<a href="https://theconversation.com/the-science-of-weather-forecasting-what-it-takes-and-why-its-so-hard-to-get-right-175740">The science of weather forecasting: what it takes and why it’s so hard to get right</a>
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<p>However, the net result of all of these factors in combination is less predictable: although low-lying coastal areas are vulnerable to flooding, forecasters may not know exactly when or how high.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1703707171030962438"}"></div></p>
<p>The other issue here is not just areas being covered by water but also the speed at which the water waves are moving, which is a factor in their destructiveness. </p>
<h2>What kind of emergency measures could be put in place?</h2>
<p>Local communities need to be warned more clearly and effectively if there is a threat of a storm surge and of coastal flooding. People and assets (like cars, anything that is moveable) should be moved from the area or kept inside. People tend to want to go to the sea to watch the waves but this puts them at more risk. Roads should be closed off where possible to keep people safe and away from the area. Floodwater management through using sandbags and similar actions should be undertaken.</p>
<p>Exactly the same measures used in places like <a href="https://www.floridadisaster.org/planprepare/">Florida in the US</a> for reducing hurricane risk should be used in South Africa, such as boarding up windows, keeping assets indoors, evacuating people from high risk areas, and moving furniture in houses to the first floor to reduce flood impacts.</p>
<p>Storm surges – and <a href="https://www.ipcc.ch/srocc/chapter/chapter-4-sea-level-rise-and-implications-for-low-lying-islands-coasts-and-communities/">sea levels rising in future</a> – are not going to go away so we need to be prepared for them.</p><img src="https://counter.theconversation.com/content/213877/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jasper Knight does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Local communities need to be warned more clearly and effectively if there is a threat of a storm surge and of coastal flooding.Jasper Knight, Professor of Physical Geography, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2087402023-07-13T12:38:15Z2023-07-13T12:38:15ZWeather forecast accuracy is crucial in a heat wave – 1 degree can mean the difference between life and death<figure><img src="https://images.theconversation.com/files/536937/original/file-20230711-26-jekcvf.jpg?ixlib=rb-1.1.0&rect=0%2C44%2C6000%2C3943&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Extreme heat can put lives at risk, making accurate forecasts essential for people working outdoors.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/exhausted-construction-worker-at-construction-site-royalty-free-image/1334826526">FG Trade/E+ via Getty Images</a></span></figcaption></figure><p>Weather forecasts have gotten quite good over the years, but their temperatures aren’t always spot on – and the result when they underplay extremes can be lethal. <a href="https://doi.org/10.3386/w31361">Even a 1-degree difference</a> in a forecast’s accuracy can be the difference between life and death, our research shows. </p>
<p>As <a href="https://scholar.google.com/citations?user=614D6AEAAAAJ&hl=en">economists</a>, <a href="https://scholar.google.com/citations?user=9VrtHcIAAAAJ&hl=en">we have</a> <a href="https://scholar.google.com/citations?user=o7NswrkAAAAJ&hl=en">studied</a> how people use forecasts to manage weather risks. In a new working paper for the National Bureau of Economic Research, we looked at how human survival <a href="https://doi.org/10.3386/w31361">depends on the accuracy of temperature forecasts</a>, particularly during heat waves like <a href="https://abcnews.go.com/US/37-million-americans-alert-dangerous-heat/story?id=100959311">large parts of the U.S.</a> have been experiencing in recent days.</p>
<p>We found that when the forecasts underplayed the risk, even small forecast errors led to more deaths.</p>
<p>Our results also show that improving forecasts pays off. They suggest that making forecasts 50% more accurate would save 2,200 lives per year across the country and would have a net value that’s nearly <a href="https://www.everycrsreport.com/files/2022-06-17_IF11914_d3e26afb6fbd9006c54580150fc833d6f1614231.pdf">twice the annual budget</a> of the National Weather Service.</p>
<h2>Forecasts that are too mild lead to more deaths</h2>
<p>In the U.S. alone, the National Oceanic and Atmospheric Administration issues <a href="https://www.noaa.gov/sites/default/files/2021-06/NOAABlueBook2022_final.pdf">1.5 million forecasts per year</a> and collects around 76 billion weather observations that help it and private companies make better forecasts.</p>
<p>We examined data on <a href="https://www.cdc.gov/">every day’s deaths</a>, weather and National Weather Service forecast in every U.S county from 2005 to 2017 to analyze the impact of those forecasts on human survival. </p>
<p>We then compared deaths in each county over the week following a day with accurate forecasts to deaths in the same county over the week following a day with inaccurate forecasts but the same weather. Because weather conditions were the same, any differences in mortality could be attributed to how people’s reactions to forecasts affected their chance of dying in that weather.</p>
<figure class="align-center ">
<img alt="Cars drive under a sign reading: Extreme heat. Save Power 4-9PM. Stay Cool" src="https://images.theconversation.com/files/536939/original/file-20230711-29-ur6l4r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536939/original/file-20230711-29-ur6l4r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536939/original/file-20230711-29-ur6l4r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536939/original/file-20230711-29-ur6l4r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536939/original/file-20230711-29-ur6l4r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536939/original/file-20230711-29-ur6l4r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536939/original/file-20230711-29-ur6l4r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Vehicles on the 110 Freeway pass warning signs on Sept. 2, 2022, during a heat wave with temperatures as high as 112 degrees Fahrenheit (44 Celsius) in the Los Angeles suburbs.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/vehicles-drive-past-a-sign-on-the-110-freeway-warning-of-news-photo/1242895722?adppopup=true">Patrick T. Fallon/AFP via Getty Images</a></span>
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<p>We found similar results when the forecast was wrong on hot days with temperatures above 86 degrees Fahrenheit (30 Celsius) and on cold days with temperatures below freezing. Both summer days that were hotter than forecast and winter days that were colder <a href="https://www.nber.org/papers/w31361">had more deaths</a>. Forecasts that went the other way and overestimated the summer heat or winter cold had little impact. </p>
<p>That doesn’t mean forecasters should exaggerate their forecasts, however. If people find that their forecasts are consistently off by a degree or two, they might change how they use forecasts or come to trust them less, leaving people at even higher risk.</p>
<h2>People are paying attention</h2>
<p>People do pay attention to forecasts and adjust their activities.</p>
<p>The <a href="https://www.bls.gov/tus/overview.htm">American Time Use Survey</a>, conducted continuously for the U.S. Bureau of Labor Statistics, shows what Americans across the country are doing on any given day. We found that on days when the forecast called for temperatures to be milder than they turned out to be – either cooler on a hot day or warmer on a cold day – people in the survey spent more time on leisure and less in home or work settings.</p>
<p><a href="https://www.eia.gov/">Electricity use</a> also varies in sync with forecasts, suggesting that people’s use of air conditioning does not just respond to the weather outside but also depends on how they planned for the weather outside.</p>
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<img alt="A man holds something over his head to shield the sun from his forehead. Other people walking across the bridge on a bright, sunny day have umbrellas and hats." src="https://images.theconversation.com/files/536940/original/file-20230711-23-mdhw2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536940/original/file-20230711-23-mdhw2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536940/original/file-20230711-23-mdhw2x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536940/original/file-20230711-23-mdhw2x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536940/original/file-20230711-23-mdhw2x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536940/original/file-20230711-23-mdhw2x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536940/original/file-20230711-23-mdhw2x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A man shields his head from the Sun as he walks across New York’s Brooklyn Bridge on a hot summer day in 2018.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/man-shields-his-head-from-the-sun-as-he-walks-across-the-news-photo/987271692">Drew Angerer/Getty Images</a></span>
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<p>However, forecasts are not used equally across society. Deaths among racial minorities are less sensitive to forecast errors, we found. That could be due in part to having less flexibility to act on forecasts, or not having access to forecasts. We will dig into this difference in future work, as the answer determines how the National Weather Service can best reach everyone.</p>
<h2>The value of better forecasts</h2>
<p>It’s clear that people use forecasts to make decisions that can matter for life and death – <a href="https://www.texasmonthly.com/travel/texas-hiking-heat-deaths-big-bend-palo-duro/">when to go hiking</a>, for example, or whether to encourage an elderly neighbor to <a href="https://theconversation.com/saving-lives-from-extreme-heat-lessons-from-the-deadly-2021-pacific-northwest-heat-wave-206737">go to a cooling center</a>.</p>
<p>So, what is the value of accurate forecasts?</p>
<p>We combined our theoretical model with <a href="https://www.epa.gov/environmental-economics/mortality-risk-valuation">federal cost-benefit estimates</a> of how people value improvements in their chances of survival. From those, we estimated people’s willingness to pay for better forecasts. That calculation accounts for the risk of dying from extreme weather and for the costs of using forecasts to reduce their risk of dying, such as the costs of altering work and play schedules or using electricity.</p>
<p>The result shows that 50% more accurate forecasts are <a href="https://doi.org/10.3386/w31361">worth at least US$2.1 billion per year</a> based on the mortality benefits alone. In comparison, the 2022 <a href="https://www.everycrsreport.com/files/2022-06-17_IF11914_d3e26afb6fbd9006c54580150fc833d6f1614231.pdf">budget of the National Weather Service</a> was less than $1.3 billion.</p>
<p>Weather forecasts have gotten steadily better over the past decades. About 68% of the next-day temperature forecasts now have an error of less than 1.8 degrees. Our results suggest investing in improved forecast accuracy would probably be worth the cost. </p>
<p>Past improvements have come from better models, better observations and better computers. Future improvements could come from similar channels or from applying recent innovations in <a href="https://theconversation.com/ai-and-machine-learning-are-improving-weather-forecasts-but-they-wont-replace-human-experts-182498">machine learning</a> and <a href="https://www.nature.com/articles/d41586-023-02084-9">artificial intelligence</a> to weather prediction and communication.</p>
<p>Climate change will <a href="https://nca2018.globalchange.gov/">increase the frequency of extremely hot days</a>, which are <a href="https://climate.nasa.gov/explore/ask-nasa-climate/3151/too-hot-to-handle-how-climate-change-may-make-some-places-too-hot-to-live/">especially important for human health</a> and survival to forecast accurately. Climate change will make the weather weirder, but weird weather can do less harm when we can see it coming.</p><img src="https://counter.theconversation.com/content/208740/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Derek Lemoine receives funding from Global Research Institute, is a Research Associate at the National Bureau of Economic Research, and is an Associate Fellow at the Centre for Economic Policy Research.</span></em></p><p class="fine-print"><em><span>Jeff Shrader receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Laura Bakkensen does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Three economists looked at years of temperature and death data and calculated the costs when forecasts miss the mark.Derek Lemoine, Associate Professor of Economics, University of ArizonaJeffrey Shrader, Assistant Professor of International and Public Affairs, Columbia UniversityLaura Bakkensen, Associate Professor of Economics and Policy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2084122023-06-29T11:15:17Z2023-06-29T11:15:17ZEl Niño could push global warming past 1.5°C – but what is it and how does it affect the weather in Europe?<figure><img src="https://images.theconversation.com/files/534592/original/file-20230628-29-3vggu2.jpg?ixlib=rb-1.1.0&rect=27%2C0%2C3072%2C2046&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A natural weather event known as El Niño is underway in the Pacific Ocean.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/el-nino-san-diego-788564623">jon sullivan/Shutterstock</a></span></figcaption></figure><p>Scientists have warned that 2024 could mark the year when global warming <a href="https://www.bbc.co.uk/news/science-environment-65839060">exceeds 1.5°C above pre-industrial levels</a>. They attribute these predictions, at least in part, to the emergence of an El Niño event.</p>
<p>An El Niño <a href="https://www.climate.gov/news-features/blogs/june-2023-enso-update-el-ni%C3%B1o-here">is declared</a> when the sea surface temperature in large parts of the central or eastern equatorial regions of the Pacific Ocean warms significantly – sometimes by as much as 2°C. This additional heat in turn warms the atmosphere. During El Niño years, this warming contributes to a temporary rise in the global temperature by a fraction of a degree. </p>
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<p><em>You can listen to more articles from The Conversation, narrated by Noa, <a href="https://theconversation.com/us/topics/audio-narrated-99682">here</a>.</em></p>
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<p>El Niño primarily affects weather in the tropics. Intense downpours that would usually fall on parts of south-east Asia or eastern Australia instead fall on the west coast of South America. This change can cause major drought and <a href="https://www.pnas.org/doi/10.1073/pnas.1409822111">flooding</a> on different continents, affecting <a href="https://www.fao.org/el-nino/en/">food production</a> and even weather-dependent sports like <a href="https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.403">cricket</a>.</p>
<p>But changes to the weather in these regions can have knock-on effects all over the world. Even thousands of kilometres away in northern Europe, El Niño tends to cause colder and drier winter weather. </p>
<p>Yet many factors affect European weather, especially during winter. So care is needed when linking unusual weather events in Europe to El Niño.</p>
<figure class="align-center ">
<img alt="Storm clouds over the Andaman Sea." src="https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534591/original/file-20230628-15-yriir7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Storm clouds over the Andaman Sea, Thailand.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/severe-storm-clouds-torrential-rain-shaft-1303569019">Ian Murdoch/Shutterstock</a></span>
</figcaption>
</figure>
<h2>What is El Niño?</h2>
<p>The Pacific Ocean spans over 13,000 kilometres from its eastern edge on the South American coast to its western margins near Indonesia. The sea surface temperature changes considerably over this vast distance. </p>
<p>Normally, the eastern edge of the Pacific Ocean is more than 5°C colder on average than the western Pacific. This is primarily due to the <a href="https://www.youtube.com/watch?v=WPA-KpldDVc">upwelling of cold water near South America</a>, a process in which colder water is pulled up from deeper down in the ocean.</p>
<p>However, this temperature contrast flattens or steepens every few years in a natural cycle called the <a href="https://www.climate.gov/news-features/blogs/enso/what-el-ni%C3%B1o%E2%80%93southern-oscillation-enso-nutshell">El Niño southern oscillation</a> (Enso). During this cycle, the strength of trade winds that blow westwards across the Pacific can strengthen or weaken, causing more or less cold water to upwell and flow along the equator. </p>
<p>We’re currently entering a period where the eastern Pacific will be warmer than it usually is – an El Niño event. Forecasts suggest that a part of the equatorial Pacific, regarded as a key indicator of Enso, has a <a href="https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.shtml">50% chance of warming by over 1.5°C</a> by the start of 2024.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/69N494UIlS8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How Pacific Ocean temperatures change during an El Niño event.</span></figcaption>
</figure>
<p>La Niña is the opposite phase of the cycle. It is instead characterised by cooler sea surface temperatures in these waters. This year brought an end to three successive La Niña years.</p>
<p>The western tropical Pacific region has some of the warmest ocean temperatures on Earth. Humid air tends to converge here, creating unstable conditions characterised by turbulent rising air known as <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/how-weather-works/what-is-convection">convection</a> by meteorologists. The result of this is towering clouds and intense rainfall. </p>
<p>The region with the highest ocean temperature tends to experience the greatest amount of rainfall. As the warmest ocean temperatures shift eastward during El Niño, so too does the location of maximum cloud cover and rainfall.</p>
<p>Each El Niño event is different. Some mainly warm the eastern Pacific Ocean, such as the <a href="https://en.wikipedia.org/wiki/1997%E2%80%9398_El_Ni%C3%B1o_event">1997-98 event</a>. Others cause more warming in the central Pacific, <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL048521">like in 2009-10</a>.</p>
<h2>How does it affect Europe’s climate?</h2>
<p>Towering clouds and intense rains in the western Pacific create atmospheric waves known as <a href="https://oceanservice.noaa.gov/facts/rossby-wave.html">Rossby waves</a>. These waves extend over thousands of kilometres and travel into and along the eastward-flowing <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/wind/what-is-the-jet-stream">jet streams</a> that encircle the planet’s mid-latitude regions. When the Rossby waves interact with the jet streams, they cause them to undulate.</p>
<p>As unsettled weather in the Pacific moves eastwards during an El Niño event, it influences the location of the peaks and troughs of these Rossby waves. This results in subtle changes in the positions of the jet streams. These alterations in the jet streams, which play a significant role in shaping weather patterns, can have notable <a href="https://www.climate.gov/news-features/featured-images/how-el-ni%C3%B1o-and-la-ni%C3%B1a-affect-winter-jet-stream-and-us-climate">effects on weather conditions</a> worldwide.</p>
<p>Depending on the specific movement of the jet stream in a particular area, the effect can either lead to warmer or cooler weather, despite El Niño warming the global climate as a whole. El Niño tends to slightly warm Europe in summer and <a href="https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/el-nino-la-nina">slightly cool</a> northern Europe in winter.</p>
<h2>External noise</h2>
<p>However, a colder-than-average winter in Europe is not guaranteed during an El Niño event. Europe’s winter climate is <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/seasons/winter/factors-that-influence-uk-winters">affected by various factors</a> beyond El Niño, including <a href="https://journals.ametsoc.org/view/journals/mwre/142/2/mwr-d-13-00104.1.xml?tab_body=abstract-display">conditions in the Atlantic</a>, the amount of Arctic sea ice and the state of the stratosphere 15-40km above us (which is <a href="https://journals.ametsoc.org/view/journals/clim/22/15/2009jcli2717.1.xml">itself affected by El Niño</a>). </p>
<p>For instance, the <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/quasi-biennial-oscillation">quasi-biennial oscillation</a> – a regular reversal of winds that blow high above the equator – can alter wind patterns in the stratosphere. This can subsequently affect the position of the North Atlantic storm track, which influences Europe’s winter weather.</p>
<p>But even then, the underlying warming trend caused by climate change is making higher temperatures more probable in all seasons. Together, these other factors make any climatic signals from El Niño harder to detect and forecast. Caution must therefore be exercised before <a href="https://www.metoffice.gov.uk/research/climate/understanding-climate/attributing-extreme-weather-to-climate-change">attributing anomalies</a> in European winter weather to El Niño alone.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p class="fine-print"><em><span>Manoj Joshi receives funding from the UK Natural Environment Research Council (NERC)</span></em></p>An El Niño weather-warming phase is underway in the Pacific – but what does this mean for the weather in Europe?Manoj Joshi, Professor of Climate Dynamics, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2079252023-06-20T04:38:20Z2023-06-20T04:38:20ZIs climate change outpacing our ability to predict extreme heatwaves?<p>When an extreme weather event happens somewhere in the world these days, it’s common to read quotes from climate scientists explaining this is exactly the kind of event we expect to see more often as climate change progresses. Such events are often devastating, but not surprising if you’ve been paying attention to the climate projections issued by scientists for many decades now.</p>
<p>But every so often, an event is so extreme it causes scientists to question our understanding of just how fast climate change is progressing. One such event was the heatwave across the Pacific Northwest region of the United States and Canada in the northern summer of 2021, when temperatures at some locations <a href="https://www.climatehubs.usda.gov/hubs/northwest/topic/2021-northwest-heat-dome-causes-impacts-and-future-outlook">hit 49°C</a> (121°F) – hotter than the all-time record for Texas. </p>
<p>It broke heat records by such a wide margin that scientists were <a href="https://edition.cnn.com/2021/07/20/world/climate-change-extreme-weather-speed-cmd-intl/index.html">quoted</a> in the <a href="https://www.nationalobserver.com/2021/07/21/news/climate-change-scientists-heat-wave-summer">media</a> saying they hadn’t expected to see temperatures so high in the Pacific Northwest until much later this century.</p>
<p>The basic concern for these scientists was that our computer climate models are best at simulating things that span large areas and long time periods, such as the annual average global temperature (what we broadly mean when we say “the climate”). They aren’t as good at simulating smaller-scale things such as an individual storm or hot wind (that is, “the weather”).</p>
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<strong>
Read more:
<a href="https://theconversation.com/statistically-impossible-heat-extremes-are-here-we-identified-the-regions-most-at-risk-204480">'Statistically impossible' heat extremes are here – we identified the regions most at risk</a>
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<p>It’s not that our models can’t simulate small-scale weather – they’re basically the same models we use for weather forecasting – it’s just very computationally expensive to have them zoom in and run in “weather mode” to get a highly detailed simulation. It’s feasible for a seven-day weather forecast, but not for a century-long climate simulation. </p>
<p>Given this limitation, the scientists quoted in the media were concerned extreme weather events might be more sensitive to climate change than our models suggest.</p>
<h2>Quantity matters too</h2>
<p>While these concerns around the <em>quality</em> of our model simulations at weather-relevant scales are valid, what’s often overlooked is the <em>quantity</em> of model simulations involved. Given the natural variability in the climate system, scientists prefer not to rely on just one model simulation when making climate projections. Instead, they run a range of century-long simulations – from just a handful up to 50 or more for the most well-resourced modelling groups – and look at the range of possible outcomes.</p>
<p>For climate metrics such as the annual average global temperature, that’s enough simulations to capture the full range of possibilities. It’s a value that doesn’t vary much from year to year because it’s an average over the entire globe, so the climate change signal dominates over natural variability. To use a slightly more technical term, we say it has a high “signal-to-noise” ratio.</p>
<p>In contrast, the weather can vary greatly over relatively short time frames, and therefore has a very low climate signal-to-noise ratio. Something like the hottest day of the year at a given location is especially noisy, because small variations in the alignment of weather patterns can make all the difference between a regular hot day and a record-shattering one. </p>
<p>In this situation, many more simulations would be required to reliably estimate the upper limit on what extreme temperatures are possible.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/weather-and-climate-are-used-interchangeably-they-shouldnt-be-110129">"Weather" and "climate" are used interchangeably. They shouldn't be</a>
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<h2>How many simulations are enough?</h2>
<p>To try and understand how many model simulations would be needed, our <a href="https://doi.org/10.1088/2752-5295/acd714">recently published research</a> used a climate model to simulate 45,000 years’ worth of daily weather at Seattle-Tacoma airport in the Pacific Northwest. </p>
<p>We then went through a process of picking out 1,000 random samples of 100 years of data from this population of 45,000 years, then 1,000 samples of 500 years, 1,000 years, 5,000 years, and so on. For each sample, we wrote down the maximum daily temperature we found (that is, the record temperature produced in each of these sample simulations). </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/532493/original/file-20230618-29-iflkh5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532493/original/file-20230618-29-iflkh5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=483&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532493/original/file-20230618-29-iflkh5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=483&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532493/original/file-20230618-29-iflkh5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=483&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532493/original/file-20230618-29-iflkh5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=607&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532493/original/file-20230618-29-iflkh5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=607&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532493/original/file-20230618-29-iflkh5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=607&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Distribution of record temperatures at Seattle Tacoma airport for 1000 repeated sub-samples of varying size.</span>
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</figure>
<p>To our surprise, as the samples got bigger, the record temperatures we found showed little evidence of stabilising. They just continued to grow, indicating even samples spanning several thousand years are insufficient to capture the full range of possible extreme temperatures. </p>
<p>The reason we kept finding hotter days as the sample size grew is that the larger samples included more weather patterns. This meant there was a greater chance of producing a unique pattern with the near-perfect alignment of weather systems to generate even more heat at our fixed location. It turns out the weather patterns that produce the most extreme heat are very unique – and indeed far rarer than we’d expected.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/532494/original/file-20230618-17-72qkt0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/532494/original/file-20230618-17-72qkt0.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=186&fit=crop&dpr=1 600w, https://images.theconversation.com/files/532494/original/file-20230618-17-72qkt0.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=186&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/532494/original/file-20230618-17-72qkt0.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=186&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/532494/original/file-20230618-17-72qkt0.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=234&fit=crop&dpr=1 754w, https://images.theconversation.com/files/532494/original/file-20230618-17-72qkt0.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=234&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/532494/original/file-20230618-17-72qkt0.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=234&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The weather pattern for the hottest day at Seattle Tacoma airport (green cross) in the observational record (June 28 2021, left) and our model simulations (right). The similarity between the two suggests extremely hot days in the model are generated by similar weather patterns as in the real world.</span>
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<h2>Luck of the draw</h2>
<p>From this perspective, the record-shattering heat experienced in the Pacific Northwest in 2021 was due not just to the overall trend of global heating, but also to the random shuffling of the weather. And our research suggests the latter factor plays an even larger role in this type of event than many climatologists had suspected. </p>
<p>This means that even though the Pacific Northwest heatwave broke records by such a wide margin, that is not necessarily a sign climate change is happening faster than expected, or that our models are doing a bad job of simulating how climate change increases the likelihood of extreme heatwaves.</p>
<p>It could simply be that our sample sizes are too small. If we had run more model simulations we could have simulated the right chance alignment of weather to generate a record-shattering day, meaning this real-life heatwave wouldn’t then have outstripped climatologists’ predictions to such an extent.</p>
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<p>
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Read more:
<a href="https://theconversation.com/the-north-american-heatwave-shows-we-need-to-know-how-climate-change-will-change-our-weather-163802">The North American heatwave shows we need to know how climate change will change our weather</a>
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<p>Advances in supercomputers have traditionally been used to run climate models at higher resolution (that is, to zoom in and get closer to “weather mode”). But when it comes to predicting just how extreme the weather can get in a warming world, we might get more bang for our buck by using those advances to run many more simulations as well. That will show us what kind of extreme heat is possible as a rare event now, and what will be more commonplace in the coming decades.</p><img src="https://counter.theconversation.com/content/207925/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The 2021 Pacific Northwest heatwave outstripped even the most severe climate prections. A new study simulated 45,000 years of weather at Seattle Tacoma airport to try and figure out why.Damien Irving, Climate Data Scientist, CSIROJames Risbey, Researcher, Oceans and Atmosphere, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2075742023-06-14T15:44:53Z2023-06-14T15:44:53ZAviation turbulence soared by up to 55% as the world warmed – new research<figure><img src="https://images.theconversation.com/files/531659/original/file-20230613-27-xtjkgf.jpg?ixlib=rb-1.1.0&rect=1609%2C334%2C1987%2C1917&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Potentially dangerous air turbulence has increased on busy flight routes across the globe.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cumulonimbus-airplane-landing-storm-clouds-77635738">Jaromir Chalabala/Shutterstock</a></span></figcaption></figure><p>Turbulence on flights isn’t most people’s idea of fun. Drinks start wobbling, hearts start racing and even rational minds start to wonder whether the aircraft can cope. But for the <a href="https://doi.org/10.3389/fpsyg.2016.00754">many people</a> who have a diagnosable fear of flying, turbulence can be terrifying.</p>
<p>That’s why it has given us no great pleasure to have published many studies over the past decade predicting that climate change will worsen turbulence in the future. But these studies have left one gaping question unanswered: given that humans started changing the climate over a century ago, has atmospheric turbulence already started to increase?</p>
<p>According to <a href="https://doi.org/10.1029/2023GL103814">our new study</a>, the answer is a resounding yes. Over the course of the past four decades, severe turbulence has increased on many busy flight routes around the world, including in Europe, the US and the north Atlantic.</p>
<figure class="align-center ">
<img alt="A man sat in front of an airplane window with his head in his hands." src="https://images.theconversation.com/files/531664/original/file-20230613-29-5kqhvn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531664/original/file-20230613-29-5kqhvn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531664/original/file-20230613-29-5kqhvn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531664/original/file-20230613-29-5kqhvn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531664/original/file-20230613-29-5kqhvn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531664/original/file-20230613-29-5kqhvn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531664/original/file-20230613-29-5kqhvn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Many people have a diagnosable fear of flying.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-sits-front-airplane-window-nervous-2027486114">Marko Aliaksandr/Shutterstock</a></span>
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<h2>The climate–turbulence link</h2>
<p>Clear-air turbulence is an invisible form of rough air that is undetectable by in-flight weather radar and is challenging to forecast. It has nothing to do with clouds and storms, but instead is generated by windshear (wind variations with altitude), which is concentrated largely in the jet streams.</p>
<p>Windshear in the jet streams has <a href="http://dx.doi.org/10.1038/s41586-019-1465-z">increased by 15%</a> at aircraft cruising altitudes since satellites began observing it in 1979. A further increase of <a href="https://doi.org/10.1029/2020EA001556">around 17%–29%</a> is projected by 2100. </p>
<p>These increases are consistent with the expected effects of climate change: <a href="https://feedbackloopsclimate.com/atmosphere">atmospheric feedback loops</a> (where warming generates further warming) are strengthening the temperature differences that generate windshear in the upper atmosphere.</p>
<p>That’s why climate models indicate that clear-air turbulence will <a href="http://dx.doi.org/10.1038/nclimate1866">become much more common in future</a>. Turbulence strong enough to pose an injury risk could <a href="http://dx.doi.org/10.1007/s00376-017-6268-2">double or triple</a> in frequency. </p>
<p>These increases are projected to occur all around the world. Some regions, including North America, the north Atlantic and Europe, are set to experience <a href="http://dx.doi.org/10.1002/2017GL074618">several hundred per cent</a> more turbulence in the coming decades. Every additional 1°C of global warming <a href="https://doi.org/10.1007/s00382-023-06694-x">will increase</a> the amount of turbulence further still.</p>
<p>And for those wondering whether climate models can be trusted with the task of making future turbulence predictions, <a href="http://dx.doi.org/10.1002/qj.4270">the evidence shows that they can</a>. The key factor limiting these predictions is not the performance of the climate models, but our understanding of turbulence itself.</p>
<figure class="align-center ">
<img alt="Weather radar screen inside the cockpit of an aircraft." src="https://images.theconversation.com/files/531933/original/file-20230614-31-aaakle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531933/original/file-20230614-31-aaakle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=225&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531933/original/file-20230614-31-aaakle.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=225&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531933/original/file-20230614-31-aaakle.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=225&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531933/original/file-20230614-31-aaakle.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=283&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531933/original/file-20230614-31-aaakle.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=283&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531933/original/file-20230614-31-aaakle.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=283&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Clear-air turbulence is undetectable by in-flight weather radar.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cu-on-airplane-weather-radar-screen-2207518471">Supamotionstock.com/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Past turbulence trends</h2>
<p>So have the predicted turbulence increases already begun? A previous analysis of pilot reports of turbulence found <a href="https://doi.org/10.1175/2008JAMC1799.1">evidence of an upward trend</a>. But the short coverage period of 12 years raised questions about whether the increase was genuine or simply a statistical blip. </p>
<p>A longer study analysed 44 years of atmospheric data from 1958 to 2001 and found <a href="https://doi.org/10.1029/2006JD008189">turbulence increases of 40%–90%</a>. But the lack of satellite data for the first half of this period leaves huge observational gaps and raises questions about the reliability of the results.</p>
<p>Our new study analyses turbulence in atmospheric data over the entire meteorological satellite era, from 1979 onwards. Although satellites cannot detect clear-air turbulence, what they can measure is the three-dimensional shape and structure of the jet streams. </p>
<p>From this we can calculate how much clear-air turbulence was being generated by the windshear. Our work has produced the most detailed picture yet of how turbulence has already started to change around the world.</p>
<p>We find that severe clear-air turbulence has increased by 55% over the north Atlantic and 41% over the US since 1979. It does go up and down from one year to the next, but there’s a clear long-term upward trend, consistent with the expected effects of climate change. We find similar increases on other busy flight routes over Europe, the Middle East and the south Atlantic.</p>
<h2>The future of turbulence</h2>
<p>We’ve been warning for the past decade that climate change would increase atmospheric turbulence. And now we see that it is happening. So what can be done to stop the more turbulent atmosphere leading to bumpier flights and more injuries to passengers and crew?</p>
<p>The aviation sector uses <a href="https://www.aviationweather.gov/turbulence/gtg">specialised turbulence forecasts</a> to plot smooth flight routes around turbulent air. These forecasts have improved greatly over the past few decades, but there is still plenty of room for improvement. </p>
<p>Technological advances might one day allow pilots to <a href="http://www.delicat.inoe.ro">remotely sense</a> invisible clear-air turbulence from the cockpit in real time. But high costs mean such technology is not yet viable.</p>
<figure class="align-center ">
<img alt="Fasten Seat belt sign on a plane." src="https://images.theconversation.com/files/531936/original/file-20230614-9255-jl252o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/531936/original/file-20230614-9255-jl252o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531936/original/file-20230614-9255-jl252o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531936/original/file-20230614-9255-jl252o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531936/original/file-20230614-9255-jl252o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531936/original/file-20230614-9255-jl252o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531936/original/file-20230614-9255-jl252o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The best advice to passengers is to keep your seatbelt fastened.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/security-on-plane-fasten-seat-belt-664653046">marako85/Shutterstock</a></span>
</figcaption>
</figure>
<p>For now, the best advice to passengers is to keep your seatbelt fastened. It’s what you do when driving down the road at 20mph, so it makes sense to do it when hurtling through the sky at 600mph. During a turbulence encounter, remember that turbulence strong enough to cause injuries is relatively rare.</p>
<p>If that thought doesn’t calm you down, we have heard that it helps to order a large drink, place it on the table in front of you and observe how little the liquid surface actually moves. You will see that the turbulent forces are rarely as bad as they feel.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
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<hr><img src="https://counter.theconversation.com/content/207574/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paul D. Williams has received funding from the Royal Society, Natural Environment Research Council, Leverhulme Trust, European Union, and Heathrow Airport.</span></em></p><p class="fine-print"><em><span>Isabel Smith receives funding from NERC</span></em></p><p class="fine-print"><em><span>Mark Prosser receives funding from NERC. </span></em></p>Turbulence strong enough to pose an injury risk could be set to double or triple in frequency in the future.Paul Williams, Professor of Atmospheric Science, University of ReadingIsabel Smith, PhD Candidate, Meteorology, University of ReadingMark Prosser, PhD Student in the Department of Meteorology, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2062652023-05-25T15:00:47Z2023-05-25T15:00:47ZFarmers face a soaring risk of flash droughts in every major food-growing region in coming decades, new research shows<figure><img src="https://images.theconversation.com/files/528081/original/file-20230524-29-ijd54y.jpg?ixlib=rb-1.1.0&rect=0%2C22%2C2761%2C1868&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A flash drought in 2012 dried out soil, harming crops in Kansas and several other states.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/darren-becker-sifts-through-arid-topsoil-under-a-ruined-news-photo/150723365">John Moore/Getty Images</a></span></figcaption></figure><p>Flash droughts develop fast, and when they hit at the wrong time, they can devastate a region’s agriculture. </p>
<p>They’re also <a href="https://doi.org/10.1038/s41467-021-26692-z">becoming increasingly common</a> as the planet warms. </p>
<p>In a new study published May 25, 2023, <a href="https://scholar.google.com/citations?hl=en&user=PRQsIDQAAAAJ">we</a> <a href="https://scholar.google.com/citations?user=4osNQTUAAAAJ&hl=en">found</a> that the risk of <a href="https://doi.org/10.1175/BAMS-D-17-0149.1">flash droughts</a>, which can develop in the span of a few weeks, is on pace to <a href="https://www.nature.com/articles/s43247-023-00826-1">rise in every major agriculture region</a> around the world in the coming decades.</p>
<p>In North America and Europe, cropland that had a 32% annual chance of a flash drought a few years ago could have as much as a <a href="https://www.nature.com/articles/s43247-023-00826-1">53% annual chance of a flash drought</a> by the final decades of this century. The result would put food production, energy and water supplies under increasing pressure. The cost of damage will also rise. A flash drought in the Dakotas and Montana in 2017 caused <a href="https://www.drought.gov/documents/flash-drought-lessons-learned-2017-drought-across-us-northern-plains-and-canadian">US$2.6 billion in agricultural damage</a> in the U.S. alone.</p>
<figure class="align-center ">
<img alt="A dry field of short, sad looking corn stalks with a farm with cattle in the background." src="https://images.theconversation.com/files/528085/original/file-20230524-19-oj5lmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528085/original/file-20230524-19-oj5lmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528085/original/file-20230524-19-oj5lmb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528085/original/file-20230524-19-oj5lmb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528085/original/file-20230524-19-oj5lmb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=511&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528085/original/file-20230524-19-oj5lmb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=511&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528085/original/file-20230524-19-oj5lmb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=511&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Stunted corn in Nebraska struggles to grow during the 2012 flash drought that covered much of the central U.S.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/WideDrought/477a0f2c1ab74163a84fb144e2674685/photo">AP Photo/Nati Harnik</a></span>
</figcaption>
</figure>
<h2>How flash droughts develop</h2>
<p>All droughts begin when precipitation stops. What’s interesting about flash droughts is <a href="https://doi.org/10.1016/j.agrformet.2022.109288">how fast</a> they reinforce themselves, with some help from the warming climate. </p>
<p>When the weather is hot and dry, soil loses moisture rapidly. Dry air extracts moisture from the land, and rising temperatures can <a href="https://doi.org/10.1175/JHM-D-21-0163.1">increase this “evaporative demand</a>.” The lack of rain during a flash drought can further contribute to the feedback processes.</p>
<p>Under these conditions, crops and vegetation begin to die much more quickly than they do during typical long-term droughts.</p>
<h2>Global warming and flash droughts</h2>
<p>In our new study, we used climate models and <a href="https://www.nature.com/articles/s43247-023-00826-1">data from the past 170 years</a> to gauge the drought risks ahead under three scenarios for how quickly the world takes action to slow global warming. </p>
<p>If greenhouse gas emissions from vehicles, power plants and other human sources continue at a high rate, we found that cropland in much of North America and Europe would have a 49% and 53% annual chance of flash droughts, respectively, by the final decades of this century. Globally, the largest projected increases would be in Europe and the Amazon.</p>
<p>Slowing emissions <a href="https://www.nature.com/articles/s43247-023-00826-1">can reduce the risk</a> significantly, but we found flash droughts would still increase by about 6% worldwide under a low-emissions scenario.</p>
<figure class="align-center ">
<img alt="Charts show the amount of cropland experiencing flash droughts today in Africa, Asia, Australia, North America, South America and Europe, and project how flash drought exposure will increase based on greenhouse gas emissions that drive global warming." src="https://images.theconversation.com/files/528076/original/file-20230524-17-exwzrk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528076/original/file-20230524-17-exwzrk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=780&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528076/original/file-20230524-17-exwzrk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=780&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528076/original/file-20230524-17-exwzrk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=780&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528076/original/file-20230524-17-exwzrk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=980&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528076/original/file-20230524-17-exwzrk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=980&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528076/original/file-20230524-17-exwzrk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=980&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Climate models indicate that more land will be in flash drought in every region in the coming decades. Three scenarios show how low (SSP126), medium (SSP245) and high (SSP585) emissions are likely to affect the amount of land in flash drought. In some regions, rising global emissions will bring more extreme rainfall, offsetting drought.</span>
<span class="attribution"><a class="source" href="https://www.nature.com/articles/s43247-023-00826-1">Jordan Christian</a></span>
</figcaption>
</figure>
<h2>Timing is everything for agriculture</h2>
<p>We’ve lived through a number of flash drought events, and they’re not pleasant. People suffer. Farmers lose crops. Ranchers may have to sell off cattle. In 2022, a flash drought slowed barge traffic on the Mississippi River, which carries <a href="https://theconversation.com/record-low-water-levels-on-the-mississippi-river-in-2022-show-how-climate-change-is-altering-large-rivers-193920">more than 90% of U.S. agriculture exports</a>.</p>
<p>If a flash drought occurs at a critical point in the growing season, it could devastate an entire crop.</p>
<p>Corn, for example, is most vulnerable during its flowering phase, <a href="https://www.agry.purdue.edu/ext/corn/news/timeless/silks.html">called silking</a>. That typically happens in the heat of summer. If a flash drought occurs then, it’s likely to have extreme consequences. However, a flash drought closer to harvest can actually help farmers, as they can get their equipment into the fields more easily.</p>
<figure class="align-center ">
<img alt="A line of houseboats that once floated on a river sit in puddles on the nearly dry riverbed during a flash drought." src="https://images.theconversation.com/files/528083/original/file-20230524-25-la125j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/528083/original/file-20230524-25-la125j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/528083/original/file-20230524-25-la125j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/528083/original/file-20230524-25-la125j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/528083/original/file-20230524-25-la125j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/528083/original/file-20230524-25-la125j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/528083/original/file-20230524-25-la125j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">During Europe’s flash drought in 2022, floating houses were left sitting on a dry riverbed in the Netherlands.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/floating-houses-sit-on-the-dry-bed-of-the-river-het-meertje-news-photo/1242700796">Thierry Monasse/Getty Images</a></span>
</figcaption>
</figure>
<p>In the southern Great Plains, <a href="https://doi.org/10.1038/s41598-022-09611-0">winter wheat</a> is at its highest risk during seeding, in September to October the year before the crop’s spring harvest. When we looked at flash droughts in that region during that fall seeding period, we found greatly reduced yields the following year.</p>
<p>Looking globally, paddy rice, <a href="https://doi.org/10.3177/jnsv.65.S2">a staple</a> for more than half the global population, <a href="https://doi.org/10.1088/1748-9326/acc8ed">is at risk</a> in northeast China and other parts of Asia. Other crops are at risk in Europe. </p>
<p>Ranches can also be hit hard by flash droughts. During the <a href="https://doi.org/10.1007/s11769-019-1066-7">huge flash drought in 2012</a> in the central U.S., cattle ran out of forage and water became scarcer. If rain doesn’t fall during the growing season for natural grasses, cattle don’t have food, and ranchers may have little choice but to <a href="https://www.drought.gov/documents/flash-drought-lessons-learned-2017-drought-across-us-northern-plains-and-canadian">sell off part of their herds</a>. Again, timing is everything.</p>
<p>It’s not just agriculture. Energy and water supplies can be at risk, too. <a href="https://www.worldweatherattribution.org/high-temperatures-exacerbated-by-climate-change-made-2022-northern-hemisphere-droughts-more-likely/">Europe’s intense summer drought in 2022</a> started as a flash drought that became a larger event as a heat wave settled in. Water levels fell so low in some rivers that power plants shut down because they couldn’t get water for cooling, compounding the region’s problems. Events like those are a window into what <a href="https://doi.org/10.1088/2515-7620/ab50ca">countries are already facing</a> and could see more of in the future.</p>
<p>Not every flash drought will be as severe as what the U.S. and Europe saw in 2012 and 2022, but we’re concerned about what may be ahead. </p>
<figure>
<iframe frameborder="0" class="juxtapose" width="100%" height="400" src="https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=a0dbaece-fa44-11ed-b5bd-6595d9b17862"></iframe>
</figure><figure><figcaption>A flash drought developed in the span of a few weeks in 2019. <a href="https://earthobservatory.nasa.gov/images/145762/a-flash-drought-dries-the-southeast">NASA Earth Observatory</a></figcaption></figure>
<h2>Can agriculture adapt?</h2>
<p>One way to help agriculture adapt to the rising risk is to improve forecasts for rainfall and temperature, which can help farmers as they make crucial decisions, such as whether they’ll plant or not.</p>
<p>When we talk with farmers and ranchers, they want to know what the weather will look like over the next one to six months. Meteorology is pretty adept at short-term forecasts that look out a couple of weeks, and at longer-term climate forecasts using computer models. But flash droughts evolve in a midrange window of time that is difficult to forecast.</p>
<p>We’re tackling the challenge of monitoring and <a href="http://hydrometeorology.oucreate.com/research/">improving the lead time and accuracy of forecasts</a> for flash droughts, as are other scientists. For example, the <a href="https://droughtmonitor.unl.edu/">United States Drought Monitor</a> has developed an <a href="https://droughtmonitor.unl.edu/ConditionsOutlooks/CurrentConditions.aspx">experimental short-term map</a> that can display developing flash droughts. As scientists learn more about the conditions that cause flash droughts and about their frequency and intensity, forecasts and monitoring tools will improve.</p>
<p>Increasing awareness can also help. If short-term forecasts show that an area is not likely to get its usual precipitation, that should immediately set off alarm bells. If forecasters are also seeing the potential for increased temperatures, that heightens the risk for a flash drought’s developing.</p>
<p>Nothing is getting easier for farmers and ranchers as global temperatures rise. Understanding the risk from flash droughts will help them, and anyone concerned with water resources, manage yet another challenge of the future.</p><img src="https://counter.theconversation.com/content/206265/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeff Basara receives funding from the National Science Foundation (NSF).</span></em></p><p class="fine-print"><em><span>Jordan Christian receives funding from the National Science Foundation (NSF). </span></em></p>If greenhouse gas emissions continue at a high rate, breadbaskets of Europe and North America will see a 50% chance of a flash drought each year by the end of this century.Jeff Basara, Associate Professor of Meteorology, University of OklahomaJordan Christian, Postdoctoral Researcher in Meteorology, University of OklahomaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2044932023-05-08T14:29:00Z2023-05-08T14:29:00ZFlooding in Nigeria is on the rise – good forecasts, drains and risk maps are urgently needed<figure><img src="https://images.theconversation.com/files/524186/original/file-20230503-20-dq7shi.jpg?ixlib=rb-1.1.0&rect=14%2C0%2C4905%2C3268&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Forecasting, risk plans and effective drainage systems can mitigate the impact of severe floods.
Photo by Pius Utomi Ekpei/AFP via Getty Images.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/tanker-truck-falls-across-the-east-west-highway-severed-by-news-photo/1244127776?adppopup=true">Getty Images </a></span></figcaption></figure><p>Nigeria is one of the most flood-prone countries in west Africa. Many areas experience annual flooding. This happens during heavy rainfall and one of the reasons is poor drainage systems. </p>
<p>The country therefore needs to make improvements. As researchers who have specialised in meteorology for about two decades we believe there are several ways it can do this. The key interventions needed are:</p>
<ul>
<li><p>understanding the impact of climate change on rainfall extremes and water resources</p></li>
<li><p>investing in a functional weather forecast system </p></li>
<li><p>addressing the problem of poor drainage.</p></li>
</ul>
<p>These actions are necessary to build resilience to floods. </p>
<p>The Nigeria Meteorological Agency and the <a href="https://nihsa.gov.ng/">Nigeria Hydrological Services Agency</a> have predicted severe flooding this year. And recent devastating flooding incidents are still fresh in the minds of Nigerians.</p>
<h2>Flooding in Nigeria</h2>
<p>Flash floods are considered the <a href="https://public.wmo.int/en/resources/world-meteorological-day/previous-world-meteorological-days/climate-and-water/floods#:%7E:text=Flash%20floods%20account%20for%20approximately,than%205%2C000%20lives%20lost%20annually">deadliest hazards related to extreme weather</a>. Nigeria is increasingly prone to them. </p>
<p>There are many predictors of floods, chief of which is increasingly heavy rains over the west African Sahel. </p>
<p>In recent decades parts of Nigeria have experienced <a href="https://www.mdpi.com/2073-4433/11/10/1084">summer rainfall extremes</a> that are more intense than before. Even dry regions like the Lake Chad River basin have begun to have record rainfalls. Downpours have submerged land areas, overrun watersheds and threatened the carrying capacity of water reservoirs. </p>
<p>This is expected to get worse as a result of global warming, according to <a href="https://www.worldweatherattribution.org/climate-change-exacerbated-heavy-rainfall-leading-to-large-scale-flooding-in-highly-vulnerable-communities-in-west-africa/#:%7E:text=Several%20hundreds%20of%20thousands%20of,as%20causes%20for%20the%20devastation">a recent scientific study</a> by the World Weather Attribution scientific team.</p>
<p>The atmospheric rivers linked to the recent heavy rainfall over the region are associated with a <a href="https://www.nature.com/articles/ncomms14966">warmer north Atlantic and Mediterranean</a>. The warming is connected with sea surface temperature anomalies in the tropical Pacific Ocean, described as Trans-Atlantic-Pacific Ocean Dipole. </p>
<p>Studies have also shown that <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/oceans/el-nino">La Niña events</a>, periodically cool ocean surface temperatures in the central and east-central equatorial Pacific. The cooling is coupled with changes in winds and pressure that cause increased rainfall over the west African Sahel. More disturbing is the rare “<a href="https://public.wmo.int/en/media/press-release/triple-dip-la-ni%C3%B1a-persists-prolonging-drought-and-flooding#:%7E:text=The%20first%20%E2%80%9Ctriple%2Ddip%E2%80%9D,World%20Meteorological%20Organization%20(WMO)">triple-dip</a>” La Niña climate event. Three consecutive years of these events will trigger more rainfall than normal in some regions.</p>
<p>The second set of drivers is geographical. For example low-land and coastal areas are flood risk areas because of <a href="https://www.eumetsat.int/severe-flooding-nigeria">rising river levels</a>. Previous flood disasters have shown that these areas are disaster prone.</p>
<p>Thirdly, flooding in Nigeria is made worse by the poor management of drainage systems. The combination of heavy rains and nonexistent or poor <a href="https://guardian.ng/sunday-magazine/poor-drainage-worsening-condition-of-lagos-roads/">drainage system</a> increases the likelihood of flash floods in cities. </p>
<p>Adding to the problem are poor waste disposal, poor urban planning, tarmacking of urban roads and construction of drainage systems without climate adaptation in mind. </p>
<h2>Building resilience against floods</h2>
<p>There’s no way to influence rainfall variability, especially in the short term. But <a href="https://www.epa.gov/green-engineering/about-green-engineering">green engineering</a> can help protect humans and the environment. </p>
<p>There are two strategies that Nigeria can easily use. They are <a href="https://theconversation.com/floods-in-nigeria-building-dams-and-planting-trees-among-steps-that-should-be-taken-to-curb-the-damage-192750#:%7E:text=Examples%20include%20the%20construction%20of,the%20major%20rivers%20in%20Nigeria">proper dam management and tree planting</a>. These initiatives will reduce the speed of water flow and reduce the impact of floods. </p>
<p>Another easy intervention is the process of risk mapping, assessment and planning for floods. This informs how resources should be distributed and how to reduce risk. It has been successful in countries such as <a href="https://blogs.worldbank.org/water/flood-hazard-and-risk-maps-key-instrument-flood-risk-management">Romania and Bulgaria</a>. </p>
<p>Then there is forecasting. It is a complex process that is continually being improved as artificial intelligence and machine learning are incorporated into the prediction technologies. Capacity building is required to improve the reliability of forecasting in the country.</p>
<p>Both the Nigeria Hydrological Services Agency and the Nigerian Meteorology Agency provide timely precipitation forecasts for water-related disaster management. The <a href="https://public.wmo.int/en">World Meteorological Organisation</a> has supported forecasting services in west Africa through its <a href="https://community.wmo.int/en/swfp-west-africa">Severe Weather Forecasting Demonstration Project</a>. The project would be more beneficial if it operated in all meteorological centres across the country.</p>
<p>For weather forecasting to deliver quality data, there is a need to continuously invest in equipment and review performance. For instance, the <a href="https://www.eoportal.org/satellite-missions/nigeriasat-2#eop-quick-facts-section">NigeriaSat-2</a> was built to provide high-resolution imagery of the Earth’s surface but it’s past its design life.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/one-of-nigerias-satellites-is-on-its-last-legs-why-this-is-worrying-165068">One of Nigeria's satellites is on its last legs: why this is worrying</a>
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</em>
</p>
<hr>
<p>Drainage systems can be developed and improved by channels or ditches, and piping that directs excess rainwater and sewage to a point of disposal. <a href="https://www.local.gov.uk/topics/severe-weather/flooding/sustainable-drainage-systems">Sustainable urban drainage systems</a> are becoming common given their multiple benefits such as reducing the effects of pollution. </p>
<p>Lastly, financing has stood out as a challenge. Nigeria’s government needs to make good use of the <a href="https://unfccc.int/establishing-a-dedicated-fund-for-loss-and-damage">climate change loss and damage fund</a> that was established at the <a href="https://unfccc.int/event/cop-27">COP27</a> meeting. Access to the funding depends on having systems for <a href="https://www.undp.org/blog/what-new-loss-and-damage-fund-needs-success">data collection, recording and reporting</a> of loss and damage finance needs.</p>
<h2>Avoiding a repeat of disaster</h2>
<p>Past floods are still fresh in people’s minds. In 2012, the destructive <a href="https://theconversation.com/nigeria-floods-4-ways-they-affect-food-security-193354">effect</a> of the excess water released from the Lagdo Reservoir in northern Cameroon and torrential summer rainfall killed 400 people, displaced millions of others, and destroyed over 152,575 hectares of farmland in Nigeria. The <a href="https://nema.gov.ng/">Nigerian Emergency Management Agency)</a> estimated a total economic loss to be about <a href="https://www.un.org/africarenewal/magazine/november-2021/dogged-massive-floods-nigeria-ramps-actions-tackle-climate-crisis">US$16.9 billion</a>. </p>
<p>In 2022, the flooding <a href="https://reliefweb.int/report/nigeria/nigeria-floods-response-flash-update-2-last-updated-1-november-2022">caused over 600 deaths and affecting an estimated 3.2 million people</a> across 34 of the country’s 36 states. The floods destroyed over 569,251 hectares of farmland.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/nigerias-floods-are-the-worst-in-a-decade-heres-how-people-try-to-cope-with-the-devastation-192781">Nigeria's floods are the worst in a decade. Here's how people try to cope with the devastation</a>
</strong>
</em>
</p>
<hr>
<p>As the 2023 flooding approaches, it is important for federal government and state agencies to work in coordination, following the seasonal climate forecast updates issued by the Nigerian Meteorological Agency. As a matter of urgency, states should set up local disaster management committees to assist in creating awareness and relocating communities living in flood-prone areas.</p><img src="https://counter.theconversation.com/content/204493/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Nigeria is expected to experience severe flooding this year. With proper planning and management its impact may not be so devastating.Victor Ongoma, Assistant Professor, Université Mohammed VI PolytechniqueVictor Nnamdi Dike, Associate professor, Chinese Academy of SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2030642023-04-20T12:55:46Z2023-04-20T12:55:46ZClimate change increases the risk of extreme wildfires around Cape Town – but it can be addressed<figure><img src="https://images.theconversation.com/files/519251/original/file-20230404-23-aqpufb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fire at the University of Cape Town, South Africa.</span> <span class="attribution"><span class="source">Photo by Brenton Geach/Gallo Images via Getty Images</span></span></figcaption></figure><p>Across the globe, <a href="https://www.sciencedirect.com/science/article/pii/S0048969719355871">many recent severe wildfires</a> have moved from wildlands into the urban periphery (the <a href="https://www.frontiersin.org/research-topics/22737/fires-in-the-wildland-urban-interface-wui-an-emerging-global-phenomenon-threatening-modern-society#overview">“wildland urban interface”</a>). In their wake, they’ve left <a href="https://doi.org/10.1016/j.ijdrr.2023.103618">death, destruction and disruption</a>. This has led to questions about the extent to which climate change is to blame.</p>
<p>A field of study called <a href="https://iopscience.iop.org/article/10.1088/2752-5295/ac6e7d?_hsmi=217900917&_hsenc=p2ANqtz--vIRNcML-N5eyhXNbUkFRofJMkOnQu1XYSZ1h_C1qgDnUdoOBCxFrsBkay1X6WZvEJ7egPLQ-Vog5y9mcE8Jm4WSnZZw">extreme event attribution</a> has developed to answer such questions. These studies quantify the links between global climate change, regional extreme weather events, and their effects on people, property and environment. </p>
<p>This branch of attribution science aims to <a href="https://link.springer.com/article/10.1007/s10584-021-03071-7">inform climate change adaptation following extreme events</a>. It also highlights that long-term, global-scale climate change is having real impacts, now, at the scale of human experience. Attribution studies can make the public <a href="https://link.springer.com/article/10.1007/s10584-021-03071-7">more acutely aware</a> of climate change effects and increase support for mitigation measures.</p>
<p>But the rapidly growing body of event attribution analyses shows a strong <a href="https://doi.org/10.1175/BAMS-D-19-0317.1">bias</a> towards extreme events in the global north. <a href="https://link.springer.com/article/10.1007/s10584-015-1432-0">Few attribution studies have considered African events</a>. </p>
<p>One of us, Zhongwei, recently led and Stefaan was involved in <a href="https://doi.org/10.1175/BAMS-D-22-0204.1">the first attribution study</a> to quantify the role of climate change in the risk of extreme fire weather conditions in southern Africa. </p>
<p>Wildfires are <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/fee.2359">complex phenomena</a>. They can only be understood fully by considering social, environmental and weather conditions together. We know, however, that extreme wildfire events occur almost exclusively under extreme fire weather conditions. Studying associations between global warming and fire weather can provide evidence for how <a href="https://www.nature.com/articles/s41612-022-00248-4">wildfire potential</a> is changing and help to inform responses. </p>
<p>We analysed the destructive <a href="https://theconversation.com/how-vulnerable-is-the-university-of-cape-town-to-destructive-wildfires-182169">April 2021 wildfire</a> on the slopes of Devil’s Peak in Cape Town, South Africa under extreme fire weather conditions. We concluded that such extreme fire weather has become around 90% more likely in a warmer world.</p>
<h2>The April 2021 Cape Town wildfire</h2>
<p>The wildfire we studied started as a small grass burn. Within a few hours it had destroyed historical buildings and priceless materials in the <a href="https://theconversation.com/significant-archives-are-under-threat-in-cape-towns-fire-why-they-matter-so-much-159299">University of Cape Town African Studies collection</a>. </p>
<p>The event received <a href="https://theconversation.com/why-the-fire-on-cape-towns-iconic-table-mountain-was-particularly-devastating-159390">widespread coverage</a>, documenting the <a href="https://www.news.uct.ac.za/article/-2021-04-23-sad-moment-as-treasured-jagger-reading-room-remembered">resulting losses</a> and the <a href="https://theconversation.com/the-table-mountain-fire-what-we-can-learn-from-the-main-drivers-of-wildfires-159477">factors responsible</a> for its destructiveness. Questions were raised that required <a href="https://www.timeslive.co.za/sunday-times/opinion-and-analysis/2021-05-09-the-fire-at-uct-not-just-the-usual-suspects/">further research</a>. One issue was the role of climate change in the weather conditions during the event.</p>
<p>Shortly after 10 am on that day, 18 April 2021, <a href="https://www.csag.uct.ac.za/2022/04/18/devils-peak-fire-18-19-april-2021-one-year-later/">hot, extremely dry and windy conditions took hold</a>. These extreme conditions resulted in <a href="https://www.news.uct.ac.za/article/-2021-06-23-reflecting-on-the-devastating-uct-fire">highly unusual fire behaviour</a>, which made suppressing the fire exceptionally challenging. Burning embers transported by the wind set vegetation alight at least <a href="https://www.sanparks.org/assets/docs/parks_table_mountain/tmnp-fire-investigation-report.pdf#page=4">350 metres</a> ahead of the main fire. </p>
<p>We found that the observed fire weather conditions were the most extreme in the 1979–2021 autumn (March–May) record. These conditions have become almost twice as likely as a result of climate change. </p>
<h2>How we came to this conclusion</h2>
<p>We used multiple climate model simulations selected from those run for the <a href="https://www.ipcc.ch/report/ar6/wg1/">Intergovernmental Panel on Climate Change</a> assessments. These gave us many years of data to provide a robust risk estimate. This is important because our study area was the smallest over which a wildfire event attribution has been done. Over small domains, local variability makes climate change signals harder to detect. The more data you have, the better the chance of picking up signals.</p>
<p>Using temperature, wind, humidity and rainfall, we calculated the value of an <a href="https://www.nwcg.gov/publications/pms437/cffdrs/fire-weather-index-system">index of fire weather (FWI)</a> over Cape Town on 18 April 2021. Then we compared a past climate before human-driven warming with our current climate to see how often the models output Cape Town autumn FWI values that are at least as extreme.</p>
<p>Our results strongly suggest that the weather conditions under which extreme Cape Town wildfires can occur are happening ever more frequently in this area in a warming world. This adds to a <a href="https://www.nature.com/articles/s43247-022-00344-6">broader body</a> of <a href="https://iopscience.iop.org/article/10.1088/1748-9326/acba33/meta">literature</a> <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020RG000726">indicating</a> that climate change is increasing the potential for “megafires” in the world’s dry-summer climates. </p>
<p>Responding to this risk requires interpreting findings in context and engaging across disciplinary boundaries. </p>
<p>In addition to suitable weather conditions, <a href="https://theconversation.com/what-science-tells-us-about-fire-hazards-facing-cape-town-and-its-surrounds-125069">wildfires require</a> a source of ignition and fuel (vegetation that can burn). Cape Town’s mountain slopes are covered by fire-prone indigenous fynbos and alien vegetation that can burn very intensely. Given the <a href="https://theconversation.com/the-table-mountain-fire-what-we-can-learn-from-the-main-drivers-of-wildfires-159477">increasing numbers of people</a> around the mountain, some fires are bound to start. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-table-mountain-fire-what-we-can-learn-from-the-main-drivers-of-wildfires-159477">The Table Mountain fire: what we can learn from the main drivers of wildfires</a>
</strong>
</em>
</p>
<hr>
<p>We outline three avenues for risk mitigation. </p>
<h2>Steps to mitigate risk</h2>
<p><strong>Adopting more holistic <a href="https://iopscience.iop.org/article/10.1088/1748-9326/ab541e/meta">fire management</a> approaches</strong></p>
<p>Focusing exclusively on fire suppression (putting fires out as <a href="https://www.westerncape.gov.za/general-publication/wildfire-season">quickly as possible whenever they occur</a>) can allow very high fuel loads to build up. Experts have warned that this widely used strategy is “<a href="https://iopscience.iop.org/article/10.1088/1748-9326/ab541e/meta">destined to fail</a>”. It can also <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14861">threaten biodiversity</a> in fire-dependent ecosystems. In the fynbos biome of south-western South Africa, fast-growing <a href="https://theconversation.com/invasive-alien-plants-in-south-africa-pose-huge-risks-but-they-can-be-stopped-94186">alien invasive species</a> and low-density <a href="https://www.iol.co.za/capeargus/news/researchers-warn-the-cape-to-prepare-for-more-disastrous-fires-like-the-2017-knysna-fires-5efb43d9-20e1-4ee4-9ba3-05abc0f73d74">urban expansion</a> into surrounding wildlands enhance the risk of megafires. </p>
<p>Instead, <a href="https://www.frontiersin.org/articles/10.3389/ffgc.2022.848254/full">researchers</a> suggest wildfire risk management should also involve limiting flammable plants and materials immediately around buildings (“defensible space”) in the urban periphery, developing evacuation plans and conducting fire-aware urban planning.</p>
<p><strong>Timely and accurate forecasting and communication of extreme fire weather risk</strong> </p>
<p>This must incorporate understanding of <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14861">fire pathways that pose the greatest risk locally</a>.</p>
<p>Doing this can aid <a href="http://www.riskreductionafrica.org/assets/files/Knynsa%20Fires%20Report%202019.pdf">short-term preparedness</a> and risk reduction. The <a href="https://www.geonetcastamericas.noaa.gov/products/navigator/details/EO_EUM_DAT_INFO_LFDI.html">fire weather index</a> that’s used in South Africa was developed for the savannah and grasslands of the hot, summer-rain Lowveld in the country’s far north-east. The ecology, climate and fire risk factors in the Lowveld are <a href="https://pta-gis-2-web1.csir.co.za/portal/apps/GBCascade/index.html?appid=a726c58f435141ba80b57fe21d3ec744">very different</a> to those in the fynbos. Consequently, this fire weather index <a href="https://doi.org/10.1186/s42408-018-0001-0">appears</a> not to have been able to identify <a href="https://doi.org/10.1016/j.ijdrr.2023.103618">unprecedented fire weather risk</a> associated with recent <a href="https://www.researchgate.net/publication/333682368_THE_KNYSNA_FIRES_OF_2017_LEARNING_FROM_THIS_DISASTER">extreme wildfires</a> in the fynbos biome.</p>
<p><strong>Further <a href="https://www.news.uct.ac.za/article/-2021-06-23-reflecting-on-the-devastating-uct-fire">research</a> to inform vegetation management</strong> </p>
<p>It’s crucial to understand which <a href="https://www.timeslive.co.za/news/south-africa/2021-04-24-born-to-burn-the-alien-trees-that-turned-cape-town-fire-into-a-disaster/">alien and possibly indigenous vegetation</a> can produce “ember showers”, such as those responsible for setting alight buildings and plants haphazardly on Devil’s Peak. <a href="https://doi.org/10.1016/j.ijdrr.2023.103618">Case studies</a> to assess factors associated with building loss and survival can also inform locally relevant policy.</p><img src="https://counter.theconversation.com/content/203064/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stefaan Conradie received PhD funding from the South African National Research Foundation (NRF). </span></em></p><p class="fine-print"><em><span>Zhongwei Liu received funding from the Coventry University Trailblazer PhD studentship scheme.</span></em></p>Autumn extreme fire weather around Cape Town in South Africa has become 90% more likely in a warmer world.Stefaan Conradie, PhD student, University of Cape TownZhongwei Liu, PhD researcher, Coventry UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2027042023-03-28T12:22:16Z2023-03-28T12:22:16ZWhy tornadoes are still hard to forecast – even though storm predictions are improving<figure><img src="https://images.theconversation.com/files/518829/original/file-20230331-18-ihfljb.jpg?ixlib=rb-1.1.0&rect=0%2C315%2C1649%2C1048&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A tornado touches down.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/noaanssl/47953539496">Morgan Schneider/OU CIMMS/NOAA NSSL</a></span></figcaption></figure><p><em>Meteorologists <a href="https://www.spc.noaa.gov">began warning about severe weather</a> with the potential for tornadoes <a href="https://www.wpc.ncep.noaa.gov/threats/threats.php">several days before</a> storms tore across <a href="https://earthobservatory.nasa.gov/images/151138/tornado-leaves-path-of-destruction-in-mississippi">the Southeast</a> and the <a href="https://www.nytimes.com/2023/03/31/us/midwest-storms-flood-weather.html">Central U.S.</a> in late March 2023. At one point, <a href="https://twitter.com/NWS/status/1641890452562403328">more than 28 million people</a> were under a <a href="https://www.weather.gov/safety/tornado-ww">tornado watch</a>. But pinpointing exactly where a tornado will touch down – like the tornadoes that hit <a href="https://www.bbc.com/news/world-us-canada-65072195">Rolling Fork, Mississippi</a>, on March 24, and towns in <a href="https://apnews.com/article/tornado-arkansas-storm-concert-79fe2da8a6b8bd92970032530b760d20">Arkansas</a>, <a href="https://www.bbc.com/news/world-us-canada-65072195">Illinois</a> and <a href="https://www.spc.noaa.gov/climo/reports/230331_rpts.html">multiple other states</a> on March 31 – still relies heavily on seeing the storms developing on radar. <a href="https://atmo.tamu.edu/people/profiles/faculty/nowotarskichristopher.html">Chris Nowotarski</a>, an atmospheric scientist, explains why, and how forecast technology is improving.</em></p>
<h2>Why are tornadoes still so difficult to forecast?</h2>
<p>Meteorologists have gotten a lot better at forecasting the conditions that make tornadoes more likely. But predicting exactly which thunderstorms will produce a tornado and when is harder, and that’s where a lot of severe weather research is focused today.</p>
<p>Often, you’ll have a line of thunderstorms in an environment that looks favorable for tornadoes, and one storm might produce a tornado but the others don’t. </p>
<p>The differences between them could be due to small differences in meteorological variables that aren’t resolved by our current observing networks or computer models. Even changes in the land surface conditions – fields, forested regions or urban environments – could affect whether a tornado forms. These small changes in the storm environment can have large impacts on the processes within storms that can make or break a tornado.</p>
<figure class="align-center ">
<img alt="Scientists stand near a truck outfitted with measuring devices with a dramatic storm on the horizon." src="https://images.theconversation.com/files/517815/original/file-20230327-18-egyw14.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517815/original/file-20230327-18-egyw14.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517815/original/file-20230327-18-egyw14.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517815/original/file-20230327-18-egyw14.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517815/original/file-20230327-18-egyw14.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517815/original/file-20230327-18-egyw14.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517815/original/file-20230327-18-egyw14.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">One way scientists gather data for understanding tornadoes is by chasing storms.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/noaanssl/52201476520/">Annette Price/CIWRO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>One of the strongest predictors of whether a thunderstorm produces a tornado relates to <a href="https://www.weather.gov/jetstream/tornado">vertical wind shear</a>, which is how the wind changes direction or speed with height in the atmosphere.</p>
<p>How wind shear interacts with rain-cooled air within storms, which we call “outflow,” and how much precipitation evaporates can influence whether a tornado forms. If you’ve ever been in a thunderstorm, you know that right before it starts to rain, you often get a gust of cold air surging out from the storm. The characteristics of that cold air outflow are important to whether a tornado can form, because tornadoes typically form in that cooler portion of the storm.</p>
<h2>How far in advance can you know if a tornado is likely to be large and powerful?</h2>
<p>The vast majority of violent tornadoes form from <a href="https://www.weather.gov/ama/supercell">supercells</a>, thunderstorms with a deep rotating updraft, called a “mesocyclone.” Vertical wind shear can enable the midlevels of the storm to rotate, and upward suction from this mesocyclone can intensify the rotation within the storm’s outflow into a tornado.</p>
<p>If you have a supercell on radar and it has strong rotation above the ground, that’s often a precursor to a tornado. Some research suggests that <a href="https://doi.org/10.1175/WAF-D-19-0099.1">a wider mesocyclone is more likely to create a stronger</a>, longer-lasting tornado than other storms.</p>
<p>Forecasters also look at the storm’s environmental conditions – temperature, humidity and wind shear. Those offer more clues that a storm is likely to produce a significant tornado.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/R7CD6MpTefs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">What radar showed as a tornado headed toward Rolling Fork, Mississippi, on March 24, 2023.</span></figcaption>
</figure>
<p>The percentage of tornadoes that <a href="https://www.weather.gov/safety/tornado-ww">trigger a warning</a> has increased over recent decades, due to <a href="https://www.weather.gov/jetstream/how">Doppler radar</a>, improved modeling and better understanding of the storm environment. About <a href="https://doi.org/10.1175/WAF-D-19-0119.1">87% of deadly tornadoes</a> from 2003 to 2017 had an advance warning.</p>
<p>The lead time for warnings has also improved. In general, it’s <a href="https://community.fema.gov/ProtectiveActions/s/article/Tornado-Alerts-and-Warnings">about 10 to 15 minutes</a> now. That’s enough time to get to your basement or, if you’re in a trailer park or outside, to find a safe facility. Not every storm will have that much lead time, so it’s important to get to shelter fast.</p>
<h2>What are researchers discovering today about tornadoes that can help protect lives in the future?</h2>
<p>If you think back to the <a href="https://www.imdb.com/title/tt0117998/">movie “Twister</a>,” in the early 1990s we were starting to do more field work on tornadoes. We were taking radar out in trucks and driving vehicles with roof-mounted instruments into storms. That’s when we really started to appreciate what we call the storm-scale processes – the conditions inside the storm itself, how variations in temperature and humidity in outflow can influence the potential for tornadoes.</p>
<p>Scientists can’t launch a weather balloon or send instruments into every storm, though. So, we also use computers to model storms to understand what’s happening inside. Often, we’ll run several models, referred to as ensembles. For instance, if nine out of 10 models produce a tornado, we know there’s a good chance the storm will produce tornadoes.</p>
<p>The National Severe Storms Laboratory has recently been experimenting with tornado warnings based on these models, called <a href="https://www.nssl.noaa.gov/projects/wof/">Warn-on-Forecast</a>, to increase the lead time for tornado warnings.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/517845/original/file-20230328-490-c5aoro.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A destroyed home with just one wall standing and furniture strewn about in Rolling Fork, Mississippi, after the tornado March 24, 2023." src="https://images.theconversation.com/files/517845/original/file-20230328-490-c5aoro.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517845/original/file-20230328-490-c5aoro.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517845/original/file-20230328-490-c5aoro.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517845/original/file-20230328-490-c5aoro.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517845/original/file-20230328-490-c5aoro.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517845/original/file-20230328-490-c5aoro.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517845/original/file-20230328-490-c5aoro.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An early warning can be the difference between life and death for people in homes without basements or cellars.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/aerial-view-of-a-destroyed-neighborhood-in-rolling-fork-news-photo/1249647508">Chandan Khanna/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>There are a lot of other areas of research. For example, to better understand how storms form, <a href="http://people.tamu.edu/%7Ecjnowotarski/research.html">I do a lot of idealized computer modeling</a>. For that, I use a model with a simplified storm environment and make small changes to the environment to see how that changes the physics within the storm itself. </p>
<p>There are also new tools in storm chasing. There’s been an explosion in the use of drones – scientists are putting sensors into unmanned aerial vehicles and <a href="https://www.colorado.edu/aerospace/2021/12/08/designing-flying-ai-systems-study-supercell-thunderstorms-close">flying them close to</a> and sometimes into the storm.</p>
<p>The focus of tornado research has also shifted from the Great Plains – the traditional “tornado alley” – <a href="https://doi.org/10.1175/JAMC-D-15-0342.1">to the Southeast</a>.</p>
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<h2>What’s different about tornadoes in the Southeast?</h2>
<p>In the Southeast there are some different influences on storms compared with the Great Plains. The Southeast has more trees and more varied terrain, and also more moisture in the atmosphere because it’s close to the Gulf of Mexico. There tend to be <a href="https://doi.org/10.1175/2008WAF2222132.1">more fatalities</a> in the Southeast, too, because <a href="https://theconversation.com/tornadoes-that-strike-at-night-are-more-deadly-and-require-more-effective-warning-systems-132955">more tornadoes form at night</a>.</p>
<figure class="align-center ">
<img alt="US map showing highest number of tornadoes in Mississippi, Alabama and western Tennessee." src="https://images.theconversation.com/files/517812/original/file-20230327-18-9tncri.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517812/original/file-20230327-18-9tncri.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=458&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517812/original/file-20230327-18-9tncri.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=458&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517812/original/file-20230327-18-9tncri.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=458&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517812/original/file-20230327-18-9tncri.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=575&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517812/original/file-20230327-18-9tncri.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=575&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517812/original/file-20230327-18-9tncri.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=575&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A map of severe tornado days from 1986 to 2015 shows a large number in the Southeast.</span>
<span class="attribution"><a class="source" href="https://www.spc.noaa.gov/">NOAA Storm Prediction Center</a></span>
</figcaption>
</figure>
<p>We tend to see more tornadoes in the Southeast that are in lines of thunderstorms called “quasi-linear convective systems.” The processes that lead to tornadoes in these storms can be different, and scientists are learning more about that.</p>
<p>Some research has also suggested the start of <a href="https://doi.org/10.1002/joc.5285">a climatological shift</a> in tornadoes toward the Southeast. It can be difficult to disentangle an increase in storms from better technology spotting more tornadoes, though. So, more research is needed.</p>
<p><em>This article was updated March 31, 2023, with tornadoes in Arkansas and the central U.S.</em></p><img src="https://counter.theconversation.com/content/202704/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Nowotarski receives funding from NSF, NOAA, DOE, and NASA.</span></em></p>Researchers are turning to computer models, drones and other methods to improve tornado forecasting.Chris Nowotarski, Associate Professor of Atmospheric Science, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1993942023-03-23T12:40:17Z2023-03-23T12:40:17ZScientists are using machine learning to forecast bird migration and identify birds in flight by their calls<figure><img src="https://images.theconversation.com/files/516482/original/file-20230320-447-474etl.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C2998%2C1994&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sandhill cranes flying above the Platte River in Nebraska.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/e6HkFZ">shannonpatrick17/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>With chatbots like ChatGPT <a href="https://theconversation.com/the-chatgpt-chatbot-is-blowing-people-away-with-its-writing-skills-an-expert-explains-why-its-so-impressive-195908">making a splash</a>, machine learning is playing an increasingly prominent role in our lives. For many of us, it’s been a mixed bag. We rejoice when our Spotify For You playlist finds us a new jam, but groan as we scroll through a slew of targeted ads on our Instagram feeds.</p>
<p>Machine learning is also changing many fields that may seem surprising. One example is <a href="https://www.researchgate.net/profile/Miguel-Jimenez-18">my discipline, ornithology – the study of birds</a>. It isn’t just solving some of the biggest challenges associated with studying bird migration; more broadly, machine learning is expanding the ways in which people engage with birds. As spring migration picks up, here’s a look at how machine learning is influencing ways to research birds and, ultimately, to protect them.</p>
<h2>The challenge of conserving migratory birds</h2>
<p>Most birds in the Western Hemisphere <a href="https://www.allaboutbirds.org/news/the-basics-how-why-and-where-of-bird-migration/#">migrate twice a year</a>, flying over entire continents between their breeding and nonbreeding grounds. While these journeys are awe-inspiring, they expose birds to many hazards en route, including <a href="https://www.nasa.gov/topics/earth/features/migratory-birds.html">extreme weather</a>, <a href="https://www.audubon.org/news/deadly-algal-bloom-could-cause-food-shortage-bay-area-migrating-waterbirds">food shortages</a> and <a href="https://news.un.org/en/story/2022/05/1118262">light pollution</a> that can attract birds and cause them to collide with buildings. </p>
<p>Our ability to protect migratory birds is only as good as the science that tells us where they go. And that science <a href="https://theconversation.com/birds-migrate-along-ancient-routes-here-are-the-latest-high-tech-tools-scientists-are-using-to-study-their-amazing-journeys-187967">has come a long way</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/3_CqIJbZx4I?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">People in Alaska, Washington state and Mexico explain what migratory birds mean to them.</span></figcaption>
</figure>
<p>In 1920, the U.S. Geological Survey launched the <a href="https://www.usgs.gov/labs/bird-banding-laboratory">Bird Banding Laboratory</a>, spearheading an effort to put bands with unique markers on birds, then recapture the birds in new places to figure out where they traveled. Today researchers can deploy a variety of lightweight tracking tags on birds to discover their migration routes. These tools have uncovered the spatial patterns of <a href="https://explorer.audubon.org/home?legend=collapse&layersPanel=expand">where and when birds of many species migrate</a>.</p>
<p>However, tracking birds has limitations. For one thing, over <a href="https://doi.org/10.1038/s41559-018-0666-4">4 billion birds migrate</a> across the continent every year. Even with increasingly affordable equipment, the number of birds that we track is a drop in the bucket. And even within a species, migratory behavior may vary across sexes or populations. </p>
<p>Further, tracking data tells us where birds have been, but it doesn’t necessarily tell us where they’re going. Migration is dynamic, and the climates and landscapes that birds fly through are constantly changing. That means it’s crucial to be able to predict their movements. </p>
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<h2>Using machine learning to forecast migration</h2>
<p>This is where machine learning comes in. Machine learning is a subfield of artificial intelligence that gives computers the ability to learn tasks or associations without explicitly being programmed. We use it to train algorithms that tackle various tasks, from <a href="https://theconversation.com/ai-and-machine-learning-are-improving-weather-forecasts-but-they-wont-replace-human-experts-182498">forecasting weather</a> to <a href="https://theconversation.com/this-march-madness-were-using-machine-learning-to-predict-upsets-91618">predicting March Madness upsets</a>.</p>
<p>But applying machine learning requires data – and the more data the better. Luckily, scientists have inadvertently compiled decades of data on migrating birds through the <a href="https://www.ncei.noaa.gov/products/radar/next-generation-weather-radar">Next Generation Weather Radar system</a>. This network, known as NEXRAD, is used to measure weather dynamics and help predict future weather events, but it also picks up signals from birds as they fly through the atmosphere. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/516489/original/file-20230320-20-ozjvkn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A tall metal tower with a spherical radar receiver on top." src="https://images.theconversation.com/files/516489/original/file-20230320-20-ozjvkn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/516489/original/file-20230320-20-ozjvkn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516489/original/file-20230320-20-ozjvkn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516489/original/file-20230320-20-ozjvkn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516489/original/file-20230320-20-ozjvkn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516489/original/file-20230320-20-ozjvkn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516489/original/file-20230320-20-ozjvkn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A NEXRAD radar at an operation center in Norman, Okla.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/NEXRAD#/media/File:LabNexrad.jpg">Andrew J. Oldaker/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p><a href="https://birdcast.info/about/">BirdCast</a> is a collaborative project of Colorado State University, the Cornell Lab of Ornithology and the University of Massachusetts that seeks to leverage that data to quantify bird migration. Machine learning is central to its operations. Researchers have known since the 1940s that <a href="https://doi.org/10.1038/156446a0">birds show up on weather radar</a>, but to make that data useful, we need to remove nonavian clutter and identify which scans contain bird movement. </p>
<p>This process would be painstaking by hand – but by training algorithms to identify bird activity, we have automated this process and unlocked decades of migration data. And machine learning allows the BirdCast team to take things further: By training an algorithm to learn what atmospheric conditions are associated with migration, we can use predicted conditions to produce <a href="http://dx.doi.org/10.1126/science.aat7526">forecasts of migration across the continental U.S.</a> </p>
<p>BirdCast began broadcasting these forecasts in 2018 and has become <a href="https://www.allaboutbirds.org/news/heres-how-to-use-the-new-migration-forecast-tools-from-birdcast/">a popular tool in the birding community</a>. Many users may recognize that radar data helps produce these forecasts, but fewer realize that it’s a product of machine learning.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/bpQ3rFlxTQE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">BirdCast provides summaries of radar-based measurements of nocturnal bird migration for the continental U.S., including estimates of numbers of birds migrating and their directions, speeds and altitudes.</span></figcaption>
</figure>
<p>Currently these forecasts can’t tell us what species are in the air, but that could be changing. Last year, researchers at the Cornell Lab of Ornithology published an automated system that uses machine learning to <a href="https://doi.org/10.1111/1365-2664.14342">detect and identify nocturnal flight calls</a>. These are species-specific calls that birds make while migrating. Integrating this approach with BirdCast could give us a more complete picture of migration.</p>
<p>These advancements exemplify how effective machine learning can be when guided by expertise in the field where it is being applied. As a <a href="https://scholar.google.com/citations?user=G8OvEN4AAAAJ&hl=en&oi=ao">doctoral student</a>, I joined <a href="https://aeroecolab.com/">Colorado State University’s Aeroecology Lab</a> with a strong ornithology background but no machine learning experience. Conversely, <a href="https://scholar.google.com/citations?user=WBov7GQAAAAJ&hl=en&oi=ao">Ali Khalighifar</a>, a postdoctoral researcher in our lab, has a background in machine learning but has never taken an ornithology class. </p>
<p>Together, we are working to enhance the models that make BirdCast run, often leaning on each other’s insights to move the project forward. Our collaboration typifies the convergence that allows us to use machine learning effectively.</p>
<h2>A tool for public engagement</h2>
<p>Machine learning is also helping scientists engage the public in conservation. For example, forecasts produced by the BirdCast team are often used to inform <a href="https://www.audubon.org/lights-out-program">Lights Out</a> campaigns. </p>
<p>These initiatives seek to reduce artificial light from cities, which attracts migrating birds and increases their chances of <a href="https://theconversation.com/cities-can-help-migrating-birds-on-their-way-by-planting-more-trees-and-turning-lights-off-at-night-152573">colliding with human-built structures</a>, such as buildings and communication towers. Lights Out campaigns can mobilize people to help protect birds at the flip of a switch. </p>
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<p>As another example, <a href="https://merlin.allaboutbirds.org/">the Merlin bird identification app</a> seeks to create technology that makes birding easier for everyone. In 2021, the Merlin staff released a feature that automates song and call identification, allowing users to identify what they’re hearing in real time, like an <a href="https://www.shazam.com/home">ornithological version of Shazam</a>.</p>
<p>This feature has opened the door for millions of people to engage with their natural spaces in a new way. Machine learning is a big part of what made it possible. </p>
<p>“Sound ID is our biggest success in terms of replicating the magical experience of going birding with a skilled naturalist,” Grant Van Horn, a staff researcher at the Cornell Lab of Ornithology who helped develop the algorithm behind this feature, told me. </p>
<h2>Taking flight</h2>
<p>Opportunities for applying machine learning in ornithology will only increase. As billions of birds migrate over North America to their breeding grounds this spring, people will engage with these flights in new ways, thanks to projects like BirdCast and Merlin. But that engagement is reciprocal: The data that birders collect will open new opportunities for applying machine learning. </p>
<p>Computers can’t do this work themselves. “Any successful machine learning project has a huge human component to it. That is the reason these projects are succeeding,” Van Horn said to me.</p><img src="https://counter.theconversation.com/content/199394/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Miguel Jimenez receives funding from the National Aeronautics and Space Administration. </span></em></p>Machine learning may not seem to have much connection with wildlife, but it’s starting to play a central role in bird conservation.Miguel Jimenez, Ph.D. student in Ecology, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1985102023-03-22T02:36:01Z2023-03-22T02:36:01ZWhat to expect when you’re expecting an El Niño (the answer might surprise you)<figure><img src="https://images.theconversation.com/files/509327/original/file-20230210-16-w2n1zt.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C3281%2C2069&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Dean Lewins/AAP</span></span></figcaption></figure><p><a href="http://www.bom.gov.au/climate/about/australian-climate-influences.shtml?bookmark=enso">La Niña and El Niño</a> are well-known terms in Australia these days. Linked to them are certain expectations: we expect wet conditions in La Niña and dry conditions in El Niño.</p>
<p>These expectations have certainly been met over the past couple of years, when regions across Australia experienced <a href="https://www.abc.net.au/news/2022-12-31/australian-weather-rain-2022-records-broken-flooding/101789262">record-breaking</a> rains and severe floods during consecutive La Niña events.</p>
<p>It might surprise you to learn, however, that not all La Niñas have been wet, nor El Niños dry. Step back to spring 2020, for example, and Australia was relatively <a href="https://www.theguardian.com/australia-news/2020/dec/01/australia-endures-hottest-spring-ever-with-average-temperatures-more-than-2c-above-average">dry and warm</a>, despite a La Niña.</p>
<p>Officials have declared the recent La Niña as over, and now we’re on an <a href="https://www.abc.net.au/news/2023-03-14/bureau-of-meteorology-declares-el-nino-watch/102093892">El Niño watch</a>. You might therefore be wondering: how often can we expect it to be dry in Australia during El Niño? Our <a href="https://doi.org/10.1071/ES22034">new research</a> sought to answer this question, and the converse for La Niña.</p>
<p>We found La Niña and El Niño are good indicators of wet and dry conditions in eastern Australia as a whole. But at some locations, including Sydney, they do little to shift the normal odds of wet and dry conditions.</p>
<figure class="align-center ">
<img alt="dry grass and basketball court with palms" src="https://images.theconversation.com/files/509328/original/file-20230210-28-l7t62z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/509328/original/file-20230210-28-l7t62z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/509328/original/file-20230210-28-l7t62z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/509328/original/file-20230210-28-l7t62z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/509328/original/file-20230210-28-l7t62z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/509328/original/file-20230210-28-l7t62z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/509328/original/file-20230210-28-l7t62z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We expect El Niños to be dry - but that’s not always the case.</span>
<span class="attribution"><span class="source">Eugene Tan/AAP</span></span>
</figcaption>
</figure>
<h2>What we did</h2>
<p>We focused on the spring season because spring rainfall has the strongest historical relationship with La Niña/El Niño. We used a simple approach known as “tercile analysis”. </p>
<p>First, we ordered the past 72 years of rainfall data from the wettest spring to the driest. We then split the data into thirds. Springs with rainfall totals in the bottom third are considered “dry”; springs in the middle third are considered “average”; and springs with rainfall totals in the top third are “wet”. </p>
<p>Splitting the data in this way means we can say that any spring normally has a 33% chance of being dry, 33% chance of being average and 33% chance of being wet. Our aim was to see if these “normal” odds change during El Niño and La Niña events.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-flap-of-a-butterflys-wings-why-autumn-is-not-a-good-time-to-predict-if-el-nino-is-coming-201940">The flap of a butterfly's wings: why autumn is not a good time to predict if El Niño is coming</a>
</strong>
</em>
</p>
<hr>
<h2>Do La Niña and El Niño change rainfall odds in eastern Australia?</h2>
<p>For rainfall averaged across eastern Australian states, the short answer is yes. </p>
<p>The figure below shows the rainfall data split into wet, average and dry boxes and also La Niña, neutral and El Niño boxes. If La Niña and El Niño did not change the rainfall odds, we would expect to see an even number of dots spread across all the boxes. However, this is not the case. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/507264/original/file-20230131-16-ht3mvi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507264/original/file-20230131-16-ht3mvi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507264/original/file-20230131-16-ht3mvi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507264/original/file-20230131-16-ht3mvi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507264/original/file-20230131-16-ht3mvi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507264/original/file-20230131-16-ht3mvi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507264/original/file-20230131-16-ht3mvi.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dry conditions during La Niña or wet conditions during El Niño are rare across eastern Australia as a whole.</span>
</figcaption>
</figure>
<p>The almost empty “dry” box in La Niña and “wet” box in El Niño show very low odds in eastern Australia of experiencing dry conditions in La Niña or wet conditions in El Niño. On the other hand, La Niña approximately doubles the normal 33% chance of experiencing wet conditions and El Niño doubles the chance of dry conditions.</p>
<p>This result is helpful in setting broad expectations across eastern Australia. But it doesn’t necessarily apply in all locations, as we discuss below.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-el-nino-doesnt-mean-certain-drought-197678">Why El Niño doesn't mean certain drought</a>
</strong>
</em>
</p>
<hr>
<h2>What about individual locations?</h2>
<p>We applied the analysis approach described above to 5km grids across Australia. </p>
<p>For parts of northern and southeastern Australia, including the Murray-Darling Basin, La Niña and El Niño significantly increase the normal odds of wet and dry springs respectively (orange and red areas). </p>
<p>But in some places, La Niña and El Niño do not markedly change the normal odds of wet or dry conditions. These locations include large parts of Western Australia, southwestern Tasmania, and southern and eastern coasts of mainland Australia, including the eastern seaboard (yellow and white areas). </p>
<p>The eastern seaboard is the easternmost part of Australia, <a href="https://www.researchgate.net/figure/The-eastern-seaboard-of-Australia-ESA-shown-on-the-left-is-roughly-the-area-between_fig5_311092024">between</a> the east coast and the Great Dividing Range. The seemingly weak relationship between La Niña and El Niño and the eastern seaboard might seem surprising. After all, just consider the large amount of rain that’s fallen on the east coast over the past couple of years during La Niña, including <a href="https://www.abc.net.au/news/2022-10-06/sydney-breaks-annual-rainfall-record/101506452">Sydney’s record-breaking 2022</a>. </p>
<p>Historically, though, rainfall on the eastern seaboard has had a <a href="https://rmets.onlinelibrary.wiley.com/doi/10.1002/joc.3741">weak relationship with La Niña and El Niño</a>. Why? Because the rainfall in this region is particularly sensitive to the frequency with which the local winds blow from the east to west. But that wind flow is not necessarily strongly linked to La Niña. </p>
<p>In 2022 there were more of these <a href="https://www.abc.net.au/news/2022-10-22/sydney-record-wet-weather-2022-due-to-shift-in-wind-direction/101562826">east-to-west wind-flow events</a> than usual, resulting in high rainfall in Sydney.</p>
<p>In the Sydney region, the normal chance of experiencing a wet spring is 33% – and this increases only slightly in a La Niña to 38%. It suggests La Niña is not a strong indicator for wet conditions in this region.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/millions-of-satellite-images-reveal-how-beaches-around-the-pacific-vanish-or-replenish-in-el-nino-and-la-nina-years-198505">Millions of satellite images reveal how beaches around the Pacific vanish or replenish in El Niño and La Niña years</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510226/original/file-20230214-18-7rdtdm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing odds of experiencing wet conditions in La Niña or dry in El Niño across Australia" src="https://images.theconversation.com/files/510226/original/file-20230214-18-7rdtdm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510226/original/file-20230214-18-7rdtdm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=282&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510226/original/file-20230214-18-7rdtdm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=282&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510226/original/file-20230214-18-7rdtdm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=282&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510226/original/file-20230214-18-7rdtdm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=355&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510226/original/file-20230214-18-7rdtdm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=355&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510226/original/file-20230214-18-7rdtdm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=355&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The odds of experiencing wet conditions in La Niña or dry in El Niño change depending on where you’re located in Australia.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>When you’re expecting an El Niño, location matters</h2>
<p>The declaration of an El Niño watch this early in the year carries <a href="https://theconversation.com/the-flap-of-a-butterflys-wings-why-autumn-is-not-a-good-time-to-predict-if-el-nino-is-coming-201940">considerable uncertainty</a>. But it’s still got people thinking about the possibility of dry conditions. </p>
<p>The odds of experiencing dry conditions in El Niño, however, change according to where you’re located in Australia. </p>
<p>In the above-right map, regions in orange and red could expect an increased chance of dry conditions. Regions in red are very likely to be dry, based on historical relationships. The chance of a dry spring is around normal (33%) in other regions. </p>
<p>Of course, while El Niño plays a large role in moderating Australia’s climate, it is <a href="https://theconversation.com/why-el-nino-doesnt-mean-certain-drought-197678?utm_source=linkedin&utm_medium=bylinelinkedinbutton">not the only driver</a> of dry conditions in Australia. Processes including the <a href="https://theconversation.com/a-rare-natural-phenomenon-brings-severe-drought-to-australia-climate-change-is-making-it-more-common-133058">Indian Ocean Dipole</a>, <a href="http://www.bom.gov.au/watl/about-weather-and-climate/australian-climate-influences.shtml?bookmark=sam">Southern Annular Mode</a> and other related or unrelated weather systems all contribute to Australia’s climate variability. </p>
<p>So it’s important to consider these factors, as well as your specific location in Australia, when interpreting what an El Niño forecast means for you. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/on-our-wettest-days-stormclouds-can-dump-30-trillion-litres-of-water-across-australia-191949">On our wettest days, stormclouds can dump 30 trillion litres of water across Australia</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/198510/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nandini Ramesh has previously received funding from the Australian Research Council, the US Department of Energy, and NASA. She is a Research Affiliate at the The University of Sydney. </span></em></p><p class="fine-print"><em><span>Carly Tozer does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Not all La Niñas are wet, nor El Niños dry – especially if you live in Sydney. So here’s how to interpret what an El Niño forecast means for you.Carly Tozer, Senior Research Scientist, CSIRONandini Ramesh, Senior Research Scientist, Data61, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1951722023-01-02T12:40:42Z2023-01-02T12:40:42ZScientists dig deep and find a way to accurately predict snowmelt after droughts<figure><img src="https://images.theconversation.com/files/497775/original/file-20221128-25-6d5d8u.jpg?ixlib=rb-1.1.0&rect=6%2C324%2C2293%2C1207&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Following historic drought in 2021, reservoir levels dropped down in the Hoover Dam on the Colorado River, which gets its waters from the melting snowpack from the Rocky Mountains of Colorado and Wyoming.</span> <span class="attribution"><a class="source" href="https://pxhere.com/en/photo/623841">(pxhere.com)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/scientists-dig-deep-and-find-a-way-to-accurately-predict-snowmelt-after-droughts" width="100%" height="400"></iframe>
<p>Where does your water supply come from? </p>
<p>If you live near mountains, for instance in British Columbia, a lot of your water probably comes from mountain snowpack. Over <a href="https://doi.org/10.1038/s41586-019-1822-y">1.9 billion people</a> globally rely on the snow melting and running off from these mountain snowpacks for their water supply.</p>
<p>Accurate predictions of this annual trend is critical for water supply planning. And forecasting models often rely on the <a href="https://www.academia.edu/47863505/Principles_of_snow_hydrology">historical relationship between mountain snowpack and the subsequent water supply</a>. </p>
<p>However, in times of unprecedented drought and a changing climate, these forecasting models seem to no longer be reliable. Following an intense drought in California in 2021, <a href="https://www.theguardian.com/us-news/2021/jun/07/california-drought-oregon-west-climate-change">snowmelt from mountain snowpack delivered significantly less water than historical models predicted</a>, meaning that reservoirs remained drier than anticipated. For the first time in 100 years, water supply models were wrong. </p>
<p>In an attempt to address the gaps in the traditional model, we recently <a href="https://doi.org/10.1029/2022GL100505">developed an updated water supply forecasting model</a> that considers additional factors, like water storage deficits in the soil and bedrock. This new model significantly improves the accuracy of water supply forecasts following drought.</p>
<h2>What are existing water supply models missing?</h2>
<p><a href="https://doi.org/10.1017/CBO9780511535673">Models used for forecasting snowmelt </a>typically consider winter rain and snowpack. But it turns out that water absorbed by the ground matters too. The amount of water absorbed into the soil and bedrock varies from year to year and is especially impacted by drought.</p>
<p>When snow melts or rain falls, almost all of it goes underground first before <a href="https://www.usgs.gov/special-topics/water-science-school/science/runoff-surface-and-overland-water-runoff">heading downstream to water supply systems </a>. The water storage processes below the surface of the ground are key to understanding the ultimate fate of rain and snow in the mountains.</p>
<figure class="align-center ">
<img alt="Schematic diagram of runoff generation in the mountains." src="https://images.theconversation.com/files/497773/original/file-20221128-12-3ska04.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/497773/original/file-20221128-12-3ska04.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=460&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497773/original/file-20221128-12-3ska04.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=460&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497773/original/file-20221128-12-3ska04.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=460&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497773/original/file-20221128-12-3ska04.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=578&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497773/original/file-20221128-12-3ska04.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=578&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497773/original/file-20221128-12-3ska04.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=578&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A diagram showing how water gets from snowpack or rain to water supply systems. Rain and snowmelt seep into the ground. Plants draw water from this region. Once the subsurface is wet, the water flows downstream to water supply systems.</span>
<span class="attribution"><a class="source" href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL100505">(Dana Lapides)</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The below ground environment is made up of complex layers of soil, fractures and weathered bedrock that can <a href="https://hydrology.usu.edu/rrp/pdfs/ch2.pdf">store, detain and transport water</a>. The details of these processes are complicated, but the overall effect can be likened to a giant sponge. </p>
<p>Over the summer, the ground dries out and it gets wet again with the arrival of rain and snowmelt in winter and spring. Once the ground is wet enough, it starts to drip. This dripping water enters the groundwater and streams and eventually goes into the water supply systems.</p>
<p>How much water drips depends on how much snowmelt and rain is received, which is included in forecasting models. It also depends on how dry the subsurface was to begin with, which is not traditionally included in forecasting models.</p>
<h2>Plants use a lot of water</h2>
<p>How dry the subsurface is this year can depend on how much water the plants used last year (or even over the last few years). In hotter, drier years, plants can use more water from underground, causing the subsurface to dry out more.</p>
<p>Recent studies show us that <a href="https://doi.org/10.1038/s41586-021-03761-3">trees routinely dry up not just soils but also weathered bedrock metres below the surface</a>.</p>
<p>Scientists are still struggling to identify how dry these mountain environments can get and how far below the surface they dry. With a drier subsurface at the start of the year, more snowmelt is needed before water starts to flow downstream to water supply systems. </p>
<p>As droughts become more frequent and intense with climate change, this process could become more important even in regions that historically haven’t faced much drought.</p>
<h2>Measuring the moisture underground</h2>
<p>Directly observing the moisture levels of the ground’s subsurface is difficult, especially when it’s stored in weathered bedrock, which can extend many metres below the ground surface and be challenging to observe. </p>
<p>In our research, we found the most accurate measurements by lowering geophysical instruments down boreholes and taking water content readings at different depths. By comparing these readings over time, we observe how <a href="https://doi.org/10.1073/pnas.1800141115">the subsurface dries out and gets wet again</a>.</p>
<figure class="align-center ">
<img alt="Researcher measures subsurface wetness conditions" src="https://images.theconversation.com/files/497767/original/file-20221128-20492-5u0m49.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/497767/original/file-20221128-20492-5u0m49.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497767/original/file-20221128-20492-5u0m49.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497767/original/file-20221128-20492-5u0m49.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497767/original/file-20221128-20492-5u0m49.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497767/original/file-20221128-20492-5u0m49.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497767/original/file-20221128-20492-5u0m49.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A USDA Forest Service employee uses an instrument to measure the moisture conditions deep underground.</span>
<span class="attribution"><span class="source">(Jamie Hinrichs/USDA Forest Service)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>However, this intensive monitoring is nearly impossible to do over large areas.</p>
<p>While we can’t look directly underground everywhere, <a href="https://hess.copernicus.org/articles/20/1459/2016/">we can track how much water enters (rain and snowmelt) and leaves (plant water use) the ground using satellite-derived data</a>.</p>
<p>By taking a running account of water going in and out of the ground, we can estimate how dry the subsurface is — a metric we call the water storage deficit. </p>
<h2>Water supply models must dig deeper</h2>
<p>Our <a href="https://doi.org/10.1038/s41586-021-03761-3">newly-developed water supply forecasting model</a> accounts for water storage deficits in both soil and bedrock. This has improved post-drought forecast accuracy substantially, taking the probability of error in the calculation of predictions from 60 per cent to about 20 per cent.</p>
<p>Since we can calculate deficits before spring snowmelts, they serve as an early warning sign and can aid water management strategies.</p>
<p>As the climate changes, the water supply challenges in California foreshadow issues that will become increasingly prevalent in British Columbia and other regions reliant on mountain snowpack. Using updated forecasting models in the future can help these regions better prepare for <a href="https://drought.ca.gov/current-drought-conditions/#overview-of-2021">continued water shortages even when snowpack seems normal</a>.</p><img src="https://counter.theconversation.com/content/195172/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dana Ariel Lapides receives funding from Simon Fraser University and the US Forest Service Southwest Pacific Research Station with funds administered through Oak Ridge Institute for Science and Engineering (ORISE). </span></em></p><p class="fine-print"><em><span>David Dralle receives funding from the US Forest Service Pacific Southwest Research Station. </span></em></p><p class="fine-print"><em><span>Jesse Hahm receives funding from Simon Fraser University, the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, and the Pacific Institute for Climate Solutions.</span></em></p><p class="fine-print"><em><span>Daniella Rempe does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Unprecedented droughts leave the subsurface drier than usual, affecting water supply in subsequent years.Dana Ariel Lapides, Postdoctoral Research Fellow, Geography, Simon Fraser UniversityDaniella Rempe, Assistant professor, Jackson School of Geosciences, The University of Texas at AustinDavid Dralle, Research officer, Hydrology, University of California, BerkeleyJesse Hahm, Department of Geography, Assistant Professor, Simon Fraser UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1941412022-11-10T13:42:59Z2022-11-10T13:42:59ZWhat is a flash drought? An earth scientist explains<figure><img src="https://images.theconversation.com/files/533774/original/file-20230623-23-ed4we5.jpg?ixlib=rb-1.1.0&rect=22%2C0%2C4962%2C3196&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">As of June 20, 2023, 64% of the U.S. corn crop faced moderate or more intense drought.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/drought-stricken-corn-on-the-mcintosh-farm-in-missouri-news-photo/150263135">Jim Watson/AFP/GettyImages</a></span></figcaption></figure><p>Many people are familiar with <a href="https://theconversation.com/what-is-a-flash-flood-a-civil-engineer-explains-187961">flash floods</a> – torrents that develop quickly after heavy rainfall. But there’s also such a thing as a flash drought, and these sudden, extreme dry spells are becoming a big concern <a href="https://theconversation.com/farmers-face-a-soaring-risk-of-flash-droughts-in-every-major-food-growing-region-in-coming-decades-new-research-shows-206265">for farmers</a> and water utilities.</p>
<p>Flash droughts start and intensify quickly, over periods of weeks to months, compared to years or decades for conventional droughts. Still, they can cause substantial economic damage, since communities have less time to prepare for the impacts of a rapidly evolving drought. In 2017, a flash drought in Montana and the Dakotas damaged crops and grasses that served as forage for cattle, causing <a href="https://www.drought.gov/documents/flash-drought-lessons-learned-2017-drought-across-us-northern-plains-and-canadian">US$2.6 billion in agricultural losses</a>.</p>
<p>Flash droughts also can increase wildfire risks, <a href="https://www.drought.gov/dews/northeast">cause public water supply shortages and reduce stream flow</a>, which harms fish and other aquatic life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/533776/original/file-20230623-25-ed4we5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of drought regions in U.S. with central Plains highlighted." src="https://images.theconversation.com/files/533776/original/file-20230623-25-ed4we5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533776/original/file-20230623-25-ed4we5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533776/original/file-20230623-25-ed4we5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533776/original/file-20230623-25-ed4we5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533776/original/file-20230623-25-ed4we5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533776/original/file-20230623-25-ed4we5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533776/original/file-20230623-25-ed4we5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A developing flash drought in the central U.S. covered 64% of corn territory and 57% of soybean territory in late June 2023. Areas marked ‘S’ are under short-term drought; ‘L’ signifies long-term drought.</span>
<span class="attribution"><a class="source" href="https://www.usda.gov/sites/default/files/documents/AgInDrought.pdf">U.S. Drought Monitor via USDA</a></span>
</figcaption>
</figure>
<h2>Less rain, warmer air</h2>
<p>Flash droughts typically result from a combination of lower-then-normal precipitation and higher temperatures. Together, these factors reduce overall land surface moisture. </p>
<p>Water constantly cycles between land and the atmosphere. Under normal conditions, moisture from rainfall or snowfall accumulates in the soil during wet seasons. Plants draw water up through their roots and release water vapor into the air through their leaves, a process called <a href="https://www.usgs.gov/special-topics/water-science-school/science/evapotranspiration-and-water-cycle">transpiration</a>. Some moisture also evaporates directly from the soil into the air. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/493942/original/file-20221107-16833-ug4zxf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic showing precipitation, evaporation and transpiration between soil and the atmosphere" src="https://images.theconversation.com/files/493942/original/file-20221107-16833-ug4zxf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/493942/original/file-20221107-16833-ug4zxf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=503&fit=crop&dpr=1 600w, https://images.theconversation.com/files/493942/original/file-20221107-16833-ug4zxf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=503&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/493942/original/file-20221107-16833-ug4zxf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=503&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/493942/original/file-20221107-16833-ug4zxf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=632&fit=crop&dpr=1 754w, https://images.theconversation.com/files/493942/original/file-20221107-16833-ug4zxf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=632&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/493942/original/file-20221107-16833-ug4zxf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=632&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Water constantly circulates between soil and the atmosphere – sometimes directly, sometimes via plants.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/media/images/evapotranspiration-sum-plant-transpiration-and-evaporation">USGS</a></span>
</figcaption>
</figure>
<p>Scientists refer to the amount of water that could be transferred from the land to the atmosphere as <a href="https://www.climate.gov/news-features/feed/evaporative-demand-increase-across-lower-48-means-less-water-supplies-drier">evaporative demand</a> – a measure of how “thirsty” the atmosphere is. Higher temperatures increase evaporative demand, which makes water evaporate faster. When soil contains enough moisture, it can meet this demand. </p>
<p>But if soil moisture is depleted – for example, if precipitation drops below normal levels for months – then evaporation from the land surface can’t provide all the moisture that a thirsty atmosphere demands. Reduced moisture at the surface increases surface air temperatures, drying out the soil further. These processes <a href="https://doi.org/10.1038/s41558-020-0709-0">amplify each other</a>, making the area increasingly hot and dry.</p>
<h2>Moist regions can have flash droughts</h2>
<p>Flash droughts started receiving more attention in the U.S. after <a href="https://doi.org/10.1175/BAMS-D-17-0149.1">notable events in 2012, 2016 and 2017</a> that reduced crop yields and increased wildfire risks. In 2012, areas in the Midwest that had near-normal precipitation conditions through May fell into severe drought conditions in June and July, causing more than <a href="https://www.ncei.noaa.gov/access/billions/">$30 billion in damages</a>. </p>
<p>New England, typically one of the <a href="https://www.climate.gov/news-features/featured-images/new-maps-annual-average-temperature-and-precipitation-us-climate">wetter U.S. regions</a>, experienced a flash drought in the summer of 2022, with areas including Boston and Rhode Island <a href="https://www.wbur.org/news/2022/08/26/climate-change-flash-drought-massachusetts">receiving only a fraction of their normal rainfall</a>. Across Massachusetts, critically low water levels forced towns to issue <a href="https://www.mass.gov/info-details/outdoor-water-use-restrictions-for-cities-towns-and-golf-courses">mandatory water restrictions</a> for residents.</p>
<h2>Planning for flash droughts in a changing climate</h2>
<p>Conventional droughts, like the <a href="https://drought.unl.edu/dustbowl/">Dust Bowl of the 1930s</a> or the current <a href="https://www.theguardian.com/environment/2022/sep/12/us-west-megadrought-climate-disaster">22-year drought across the southwestern U.S.</a>, develop over periods of years. Scientists rely on monitoring and prediction tools, such as measurements of temperature and rainfall, as well as models, to forecast their evolution. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CW7X5M_lqcT/?utm_source=ig_web_copy_link\u0026igshid=MzRlODBiNWFlZA==","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Predicting flash drought events that occur on monthly to weekly time scales is much harder with current data and tools, largely due to the <a href="https://doi.org/10.1029/2019EA000586">chaotic nature of weather and limitations in weather models</a>. That’s why weather forecasters don’t typically make projections <a href="https://www.washingtonpost.com/weather/2019/11/07/science-says-specific-weather-forecasts-cant-be-made-more-than-ten-days-advance/">beyond 10 days</a> – there is a lot of variation in what can happen over longer time spans.</p>
<p>And climate patterns can shift from year to year, adding to the challenge. For example, Boston had <a href="https://twitter.com/NWSBoston/status/1552127339277889536">a very wet summer in 2021</a> before its very dry summer in 2022.</p>
<p>Scientists expect climate change to make precipitation <a href="https://doi.org/10.1038/s41598-017-17966-y">even more variable</a>, especially in wetter regions like the U.S. Northeast. This will make it more difficult to forecast and prepare for flash droughts well in advance. </p>
<p>But new monitoring tools that measure evaporative demand can provide <a href="https://doi.org/10.1175/BAMS-D-14-00219.1">early warnings</a> for regions experiencing abnormal conditions. Information from these systems can give farmers and utilities sufficient lead time to adjust their operations and minimize their risks. </p>
<p><em>This is an updated version of an article originally published on Nov. 10, 2022.</em></p><img src="https://counter.theconversation.com/content/194141/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Antonia Hadjimichael receives funding from the U.S. Department of Energy</span></em></p>Flash droughts can develop within a few weeks, causing water shortages, damaging crops and worsening fire risks.Antonia Hadjimichael, Assistant Professor of Geosciences, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1877412022-09-20T20:14:01Z2022-09-20T20:14:01ZClimate change is making rain difficult to predict – we trained an AI to help tropical countries adapt<figure><img src="https://images.theconversation.com/files/484600/original/file-20220914-11-jn6m9j.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5892%2C3925&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/moment-where-cumulonimbus-storm-cloud-gathered-1291824019">Muhammad Qadri Anwar/Shutterstock</a></span></figcaption></figure><p>While rivers and reservoirs run <a href="https://theconversation.com/rivers-worldwide-are-running-dry-heres-why-and-what-we-can-do-about-it-189270">dangerously low</a> in Europe, there is catastrophic flooding in <a href="https://theconversation.com/a-climate-scientist-on-the-planets-simultaneous-disasters-from-pakistans-horror-floods-to-europes-record-drought-189626">Pakistan</a> and <a href="https://theconversation.com/americas-summer-of-floods-what-cities-can-learn-from-todays-climate-crises-to-prepare-for-tomorrows-189293">the US</a>. Whether it’s a drought or a deluge, being able to accurately forecast rain is important to protect lives and manage water safely.</p>
<p>That has become more difficult in recent decades. Climate change and deforestation have <a href="https://theconversation.com/human-disruption-to-earths-freshwater-cycle-has-exceeded-the-safe-limit-our-research-shows-182562">warped Earth’s freshwater cycle</a>, shifting rainfall patterns towards extreme events like severe droughts and downpours. Catastrophic floods have been on the rise globally <a href="https://public.wmo.int/en/media/press-release/weather-related-disasters-increase-over-past-50-years-causing-more-damage-fewer">in the last 50 years</a> and incidences of flash flooding, when torrential rain falls in a very short period, have increased, particularly in tropical countries where <a href="https://www.youtube.com/watch?v=Z6EjpKN9ai0">high temperatures</a> have made <a href="https://www.nssl.noaa.gov/education/svrwx101/thunderstorms/">thunderstorms</a> more common.</p>
<p>Developed countries like the UK have invested in satellites and radars for more accurate weather forecasting. These high-tech systems are particularly effective in temperate climates where rainfall typically occurs over <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008RS003984">several kilometres</a> and moves in wide bands known as weather fronts. Measurements of rainfall over distances of 5 km or greater, which satellites and radars are capable of, are often sufficient for forecasting rain at this scale. </p>
<p>In tropical countries, where climate change is expected to have a far <a href="https://www.concern.net/news/countries-most-affected-by-climate-change">greater impact</a>, systems that can forecast rain at distances of less than a kilometre are needed. This is because of something called <a href="https://www.internetgeography.net/topics/what-is-convectional-rainfall/">convectional rainfall</a>, which is common in the tropics. </p>
<p>Convectional rainfall occurs when heated air rises upwards along with water vapour, which condenses to form clouds at a high altitude. These clouds are not carried away by the wind, and so rain falls in the same place it originated. </p>
<p>Systems capable of forecasting convectional rainfall would help authorities give advance warning, preventing deaths and flood damage. They could also help people manage this rainwater to benefit farms, with efficient drainage and irrigation measures.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/RkgThul2El8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Most tropical countries fall within <a href="https://worldpopulationreview.com/country-rankings/low-income-countries">low or middle income</a> bands. Forecasting rain over distances smaller than a kilometre is expensive – weather satellites are often not feasible. Dense vegetation and hilly terrain, also common in tropical regions, can profoundly shape local weather by causing <a href="https://www.internetgeography.net/topics/what-is-convectional-rainfall/">humid air to rise and condense</a>, making conventional weather forecasting even trickier.</p>
<p>To solve these problems, we set out to develop a cheap way of providing street-by-street forecasting.</p>
<h2>AI-based tropical rainfall forecasting</h2>
<p>Rainfall is the result of complex interactions between different components of the atmosphere such as temperature, humidity, pressure and wind speed which can be easily measured by sensors. We investigated whether artificial intelligence could use this information to compile a rainfall forecast in northern Malaysia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A 3D illustration of a landscape with weather sensors linked in a network." src="https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=423&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=423&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=423&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484633/original/file-20220914-9486-tykdiw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Multiple sensors link up to form a network that can predict rainfall over a large area.</span>
<span class="attribution"><span class="source">Ogochukwu Ejike</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The forecasting system we developed is essentially an intelligent computer programme that can predict whether it will rain, how intense that rain will be and how long it will last at any location with greater than 90% accuracy at least 96 hours in advance. </p>
<p>We tested its forecasting accuracy against past weather conditions which preceded rain falling. If this algorithm included data from sensors measuring the depth and flow rate of rivers, it could predict whether rain might cause flooding, and if so, when and for how long.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two line plots depicting forecasted rainfall intensity and duration and the actual values." src="https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=447&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=447&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=447&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=562&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=562&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485631/original/file-20220920-23-i7u8tz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=562&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How the forecast compared with actual rainfall.</span>
<span class="attribution"><span class="source">Ogochukwu Ejike</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The devices used to measure weather conditions can be connected to the internet to form a network that offers regional forecasting. Adding more devices to the network will improve the accuracy of the forecast, which is updated hourly.</p>
<p>Working with University of Malaysia Perlis, we have already created an online network of <a href="https://unisense.ceastech.com/?m=1.578842,105.766056,6">existing weather sensors</a> that collects data for our algorithm to use. Most of these weather stations are separated by tens of kilometres – too far apart to provide detailed rain forecasting in most areas. </p>
<p>But, as more sensors are added, the forecasting system will hopefully one day ensure that vulnerable communities can better prepare for extreme weather events, and build resilience to the rapidly changing climate.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>High humidity, terrain and wind make rain forecasting particularly tricky in the tropics.Ogochukwu Ejike, PhD Candidate, Computing and Informatics, University of the West of ScotlandDavid Ndzi, Head of Computing, University of the West of ScotlandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1862612022-07-19T12:40:50Z2022-07-19T12:40:50ZHeatwave: why extreme weather forecasts have improved so much<p>The UK has recorded its <a href="https://www.itv.com/news/2022-07-19/uk-records-hottest-day-on-record-as-temperatures-soar-to-over-39c">hottest ever temperature</a>, passing 40°C for the first time. But you can’t deny it had fair warning. The Met Office issued an amber weather warning six days before the heatwave and upgraded it to red three days later, enough time to trade cooling-down tips with friends and stock up on ice lollies. </p>
<p>It’s easy to take modern weather prediction technology and warning systems for granted, but the new advancements save lives. The most well known weather forecast failure in UK history happened <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/case-studies/great-storm">35 years ago</a>. Hours after veteran weather presenter <a href="https://www.thesun.co.uk/news/2548443/ichael-fish-1987-hurricane-storm/">Michael Fish </a> said there was no hurricane coming “but it will be very windy in Spain”, the a devastating storm raged across the country and claimed 18 lives. </p>
<p>A huge amount has changed since 1987. Weather forecasts are more precise, reliable, and better communicated. <a href="https://news.sky.com/story/michael-fish-got-the-storm-of-1987-wrong-but-modern-supercomputers-may-have-missed-it-too-11076659">Re-analysis</a> shows that in 2022 the 1987 storm would be noticed a few days ahead, but there would have likely been uncertainty. An amber warning would probably have been sent out and the storm would have been named, alerting the public. So how exactly has forecasting improved?</p>
<p>The real change is in people’s experience of extreme weather. For example, <a href="https://www.bbc.co.uk/news/uk-60426382">Storm Eunice</a> in February 2022, which broke the English wind gust record at 122 miles per hour. The storm was forecast days ahead, with a <a href="https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2022/red-weather-warnings-in-force-for-storm-eunice">rare red warning</a> issued the night before. </p>
<figure class="align-center ">
<img alt="Waves crash against beach with yellow sky." src="https://images.theconversation.com/files/472825/original/file-20220706-5011-zs61fq.jpg?ixlib=rb-1.1.0&rect=51%2C34%2C5699%2C3794&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/472825/original/file-20220706-5011-zs61fq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/472825/original/file-20220706-5011-zs61fq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/472825/original/file-20220706-5011-zs61fq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/472825/original/file-20220706-5011-zs61fq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/472825/original/file-20220706-5011-zs61fq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/472825/original/file-20220706-5011-zs61fq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Waves start to increase as Storm Eunice gathers momentum around Porthcawl lighthouse in South Wales UK.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/waves-start-increase-storm-eunice-gathers-2124985670">Shutterstock</a></span>
</figcaption>
</figure>
<p>The high pressures that drive heatwaves are a little easier to predict with older models, as the physics limits the changes possible over distance. So I expect an extreme heat event would have been predicted a few days ahead even in 1987 (although the recent high temperatures wouldn’t have been hit back then as they are <a href="https://www.metoffice.gov.uk/research/climate/understanding-climate/uk-and-global-extreme-events-heatwaves">worsened by climate change</a>). </p>
<p>However, today there would be more confidence in the predictions and, crucially, there are better mechanisms for warning the public. Without such warnings, it’s likely far more people would die.</p>
<h2>What has changed</h2>
<p>Most of us walk around with a computer in our pockets several times more powerful than the one used to forecast weather <a href="https://www.huffingtonpost.co.uk/aidan-mcgivern/what-if-the-1987-great-st_b_18245050.html">in 1987</a>. It was among the fastest in the world at the time, capable of 4 million calculations per second. The current <a href="https://www.metoffice.gov.uk/about-us/what/technology/supercomputer">Met Office</a> supercomputer does 14,000 trillion per second.</p>
<p>Since the 1920s, weather forecasting has been done by numerical models that calculate <a href="https://www.metoffice.gov.uk/research/approach/modelling-systems/unified-model/weather-forecasting">physics on a grid</a>. In the 1950s, this process <a href="https://www.metoffice.gov.uk/weather/learn-about/how-forecasts-are-made/computer-models/history-of-numerical-weather-prediction">moved to computers</a>, which made timely forecasting more feasible, as humans cannot process the calculations quickly enough to do it on their own. The forecast is made using a grid of locations, calculating the weather conditions at a point then stepping forward in time. </p>
<figure class="align-center ">
<img alt="Rain on a city road" src="https://images.theconversation.com/files/474527/original/file-20220718-14-8jqaq2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474527/original/file-20220718-14-8jqaq2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474527/original/file-20220718-14-8jqaq2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474527/original/file-20220718-14-8jqaq2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474527/original/file-20220718-14-8jqaq2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474527/original/file-20220718-14-8jqaq2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474527/original/file-20220718-14-8jqaq2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">UK weather can be unpredictable.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rain-city-road-pavement-car-close-1034500234">Viktor Gladkov/Shutterstock</a></span>
</figcaption>
</figure>
<p>As computers improve, they can make meteorological calculations faster. The grid and time-steps can be smaller. The <a href="https://www.metoffice.gov.uk/research/approach/modelling-systems/unified-model/weather-forecasting">modern numerical model</a> uses a grid smaller than a kilometre between points over the UK (and 10km across the globe). In 1987 weather forecasters used a global grid of points 150km apart. </p>
<p>The science the models rely on is better understood today. For example, we understand how <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/wind/sting-jet">sting jets</a>, small areas of intense winds, develop. </p>
<h2>Looking to the skies</h2>
<p>Satellites transformed meteorology. They were incorporated into computer models from the 90s. One of the key problems in 1987 was a lack of weather monitoring at sea, but satellites and buoys filled the gap. A network of buoys around the UK were set up as a direct result of the 1987 storm. </p>
<p>Techniques to make best use of observations are <a href="https://research.reading.ac.uk/met-darc/">rapidly developing</a>. But the main change is the sheer quantity of observations available. We have less ground stations but more overall observation points from satellites, radars, instruments mounted to <a href="https://public.wmo.int/en/programmes/global-observing-system/amdar-observing-system">commercial aircraft</a> and other systems. Satellite readings provide hundreds of billions of observations each day. </p>
<p>Satellite data brought southern hemisphere forecasts (where less land means less surface observations) up to a <a href="https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.736">similar accuracy </a> to those the northern hemisphere. Previously, southern hemisphere forecasts often had a day’s less lead time. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/474544/original/file-20220718-51582-95mmiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474544/original/file-20220718-51582-95mmiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474544/original/file-20220718-51582-95mmiu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474544/original/file-20220718-51582-95mmiu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474544/original/file-20220718-51582-95mmiu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474544/original/file-20220718-51582-95mmiu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474544/original/file-20220718-51582-95mmiu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Most people know dark clouds mean rain.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/dramatic-sky-stormy-clouds-142022221">Shebeko/Shutterstock</a></span>
</figcaption>
</figure>
<p>The UK is also living in the golden age of radar. In 2018 a <a href="https://www.rmets.org/metmatters/met-office-uk-weather-radar-network-upgraded">radar network upgrade</a> was completed which enabled weather forecasters to start using new radar technology that can tell us more information about the shape and size of raindrops and snowflakes, not just their location. </p>
<h2>Talking about it</h2>
<p>Instead of a regional TV forecast, in 2022 we tend to rely on apps forecasting for our neighbourhood. Street-level forecasts are tricky to get right. In changeable weather conditions, such as summer showers, forecasters know to expect showers, but not their precise location. Like heating water on the hob, you can predict the timing of boiling, but you can’t predict the locations of each bubble. </p>
<p>The UK is notorious for unpredictable weather. Sunny days can turn into downpours within minutes. Winter weather in the UK is dominated by large bands of cloud, wind and rain, which makes predictions more reliable. However, when meteorologists know an area should expect showers, but not the precise location and timing, an excellent forecast can appear poor to a casual user. </p>
<p>Weather forecasters believe the UK public do not understand scientific uncertainty so don’t communicate how sure they are about predictions. But in the US, weather forecasts have given confidence in <a href="https://gc.copernicus.org/articles/2/101/2019/">a chance of rain</a> for decades). </p>
<h2>Looking ahead</h2>
<p>Weather forecasting will <a href="https://theconversation.com/why-the-weather-forecast-will-always-be-a-bit-wrong-101547">always remain uncertain</a>, thanks to the <a href="https://www.metlink.org/blog/weather-climate-and-chaos-theory/">butterfly effect</a>, which means small changes in conditions can lead to big changes later. </p>
<p>But the process is improving. Big things to come include more joined up thinking. For instance, scientists are thinking about connecting <a href="https://www.mdpi.com/2073-4441/11/4/725">weather and flooding models</a>. </p>
<p>Computer models will get more realistic. Satellites (and other observation systems) are improving. I’m <a href="https://www.wivern.polito.it/">working on a satellite</a> we hope to fly in 10 years that will measure wind speed in clouds across the globe.</p>
<p>As climate change is driving <a href="https://www.metoffice.gov.uk/research/climate/understanding-climate/attributing-extreme-weather-to-climate-change">more extreme weather</a> worldwide, weather forecasts have never been more important. With more flooding, wildfires, storms and record breaking temperatures, it can be a matter of life and death.</p><img src="https://counter.theconversation.com/content/186261/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rob Thompson receives funding from ESA and previously NERC. </span></em></p>The Met Office issued its heatwave warning six days before the mercury peaked – potentially saving many lives.Rob Thompson, Postdoctoral Research Scientist in Meteorology, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1824982022-05-26T12:25:58Z2022-05-26T12:25:58ZAI and machine learning are improving weather forecasts, but they won’t replace human experts<figure><img src="https://images.theconversation.com/files/465128/original/file-20220524-20-scw9mi.jpg?ixlib=rb-1.1.0&rect=0%2C11%2C7458%2C4953&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Meteorologist Todd Dankers monitors weather patterns in Boulder, Colorado, Oct. 24, 2018. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/meteorologist-todd-dankers-is-monitoring-weather-patterns-news-photo/1052979764">Hyoung Chang/The Denver Post via Getty Images</a></span></figcaption></figure><p>A century ago, English mathematician <a href="https://mathshistory.st-andrews.ac.uk/Biographies/Richardson/">Lewis Fry Richardson</a> proposed a startling idea for that time: constructing a systematic process based on math for predicting the weather. In his 1922 book, “<a href="https://www.emetsoc.org/resources/rff/">Weather Prediction By Numerical Process</a>,” Richardson tried to write an equation that he could use to solve the dynamics of the atmosphere based on hand calculations.</p>
<p>It didn’t work because not enough was known about the science of the atmosphere at that time. “Perhaps some day in the dim future it will be possible to advance the computations faster than the weather advances and at a cost less than the saving to mankind due to the information gained. But that is a dream,” Richardson concluded. </p>
<p>A century later, modern weather forecasts are based on the kind of complex <a href="https://www.irishtimes.com/news/science/lewis-fry-richardson-s-remarkable-weather-forecast-factory-1.2473954">computations that Richardson imagined</a> – and they’ve become more accurate than anything he envisioned. Especially in recent decades, steady progress in research, data and computing has enabled a “<a href="https://doi.org/10.1038/nature14956">quiet revolution of numerical weather prediction</a>.”</p>
<p>For example, a forecast of heavy rainfall two days in advance is <a href="https://www.wpc.ncep.noaa.gov/html/hpcverif.shtml#qpf">now as good</a> as a same-day forecast was in the mid-1990s. Errors in the predicted tracks of hurricanes have been <a href="https://www.nhc.noaa.gov/verification/verify5.shtml">cut in half</a> in the last 30 years. </p>
<p>There still are major challenges. Thunderstorms that produce tornadoes, large hail or heavy rain remain difficult to predict. And then there’s chaos, often described as the “butterfly effect” – the fact that small changes in complex processes make weather <a href="https://www.discovery.com/science/Butterfly-Effect-Predict-the-Weather">less predictable</a>. Chaos limits our ability to make precise forecasts <a href="https://doi.org/10.1175/JAS-D-18-0269.1">beyond about 10 days</a>. </p>
<p>As in many other scientific fields, the proliferation of tools like artificial intelligence and machine learning holds great promise for weather prediction. We have seen some of what’s possible in <a href="https://scholar.google.com/citations?user=vfbhQHkAAAAJ&hl=en">our research</a> on <a href="https://scholar.google.com/citations?user=xMygrTgAAAAJ&hl=en">applying machine learning</a> to forecasts of high-impact weather. But we also believe that while these tools open up new possibilities for better forecasts, many parts of the job are handled more skillfully by experienced people. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9Qb2tHOz4fw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Australian meteorologist Dean Narramore explains why it’s hard to forecast large thunderstorms.</span></figcaption>
</figure>
<h2>Predictions based on storm history</h2>
<p>Today, weather forecasters’ primary tools are <a href="https://www.ncei.noaa.gov/products/weather-climate-models/numerical-weather-prediction">numerical weather prediction models</a>. These models use observations of the current state of the atmosphere from sources such as weather stations, weather balloons and satellites, and solve equations that govern the motion of air. </p>
<p>These models are outstanding at predicting most weather systems, but the smaller a weather event is, the more difficult it is to predict. As an example, think of a thunderstorm that dumps heavy rain on one side of town and nothing on the other side. Furthermore, experienced forecasters are remarkably good at synthesizing the huge amounts of weather information they have to consider each day, but their memories and bandwidth are not infinite.</p>
<p>Artificial intelligence and machine learning can help with some of these challenges. Forecasters are using these tools in several ways now, including making predictions of high-impact weather that the models can’t provide. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1197226603258007552"}"></div></p>
<p>In a project that started in 2017 and was reported in a <a href="https://doi.org/10.1175/BAMS-D-20-0186.1">2021 paper</a>, we focused on heavy rainfall. Of course, part of the problem is defining “heavy”: Two inches of rain in New Orleans may mean something very different than in Phoenix. We accounted for this by using observations of unusually large rain accumulations for each location across the country, along with a history of forecasts from a numerical weather prediction model. </p>
<p>We plugged that information into a machine learning method known as “<a href="https://www.ibm.com/cloud/learn/random-forest">random forests</a>,” which uses many decision trees to split a mass of data and predict the likelihood of different outcomes. The result is a tool that forecasts the probability that rains heavy enough to generate flash flooding will occur. </p>
<p>We have since applied similar methods to forecasting of tornadoes, large hail and severe thunderstorm winds. <a href="https://doi.org/10.1175/MWR-D-20-0194.1">Other</a> <a href="https://www2.mmm.ucar.edu/projects/ncar_ensemble/camviewer/">research</a> <a href="https://doi.org/10.1175/WAF-D-19-0258.1">groups</a> are developing similar tools. National Weather Service forecasters are using some of these tools to better assess the likelihood of hazardous weather on a given day.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/463870/original/file-20220518-26-iwawkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two maps showing a machine learning forecast and actual flooding in the mid-Atlantic states after Hurricane Ida in 2021." src="https://images.theconversation.com/files/463870/original/file-20220518-26-iwawkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463870/original/file-20220518-26-iwawkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463870/original/file-20220518-26-iwawkp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463870/original/file-20220518-26-iwawkp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463870/original/file-20220518-26-iwawkp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463870/original/file-20220518-26-iwawkp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463870/original/file-20220518-26-iwawkp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An excessive rainfall forecast from the Colorado State University-Machine Learning Probabilities system for the extreme rainfall associated with the remnants of Hurricane Ida in the mid-Atlantic states in September 2021. The left panel shows the forecast probability of excessive rainfall, available on the morning of Aug. 31, more than 24 hours ahead of the event. The right panel shows the resulting observations of excessive rainfall. The machine learning program correctly highlighted the corridor where widespread heavy rain and flooding would occur.</span>
<span class="attribution"><span class="source">Russ Schumacher and Aaron Hill</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Researchers also are embedding machine learning within numerical weather prediction models to speed up tasks that can be intensive to compute, such as predicting how water vapor gets converted to rain, snow or hail. </p>
<p>It’s possible that machine learning models could eventually replace traditional numerical weather prediction models altogether. Instead of solving a set of complex physical equations as the models do, these systems instead would process thousands of past weather maps to learn how weather systems tend to behave. Then, using current weather data, they would make weather predictions based on what they’ve learned from the past. </p>
<p>Some studies have shown that machine learning-based forecast systems <a href="https://doi.org/10.1029/2020MS002109">can predict general weather patterns</a> as well as <a href="https://ai.googleblog.com/2021/11/metnet-2-deep-learning-for-12-hour.html">numerical weather prediction models</a> while using only a fraction of the computing power the models require. These new tools don’t yet forecast the details of local weather that people care about, but with many researchers carefully testing them and inventing new methods, there is promise for the future. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/463872/original/file-20220518-25-j50eqa.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Maps of an evolving machine learning forecast for an outbreak of severe weather in the US Midwest in December 2021." src="https://images.theconversation.com/files/463872/original/file-20220518-25-j50eqa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/463872/original/file-20220518-25-j50eqa.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/463872/original/file-20220518-25-j50eqa.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/463872/original/file-20220518-25-j50eqa.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/463872/original/file-20220518-25-j50eqa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/463872/original/file-20220518-25-j50eqa.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/463872/original/file-20220518-25-j50eqa.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A forecast from the Colorado State University-Machine Learning Probabilities system for the severe weather outbreak on Dec. 15, 2021, in the U.S. Midwest. The panels illustrate the progression of the forecast from eight days in advance (lower right) to three days in advance (upper left), along with reports of severe weather (tornadoes in red, hail in green, damaging wind in blue).</span>
<span class="attribution"><span class="source">Russ Schumacher and Aaron Hill</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>The role of human expertise</h2>
<p>There are also reasons for caution. Unlike numerical weather prediction models, forecast systems that use machine learning are not constrained by the physical laws that govern the atmosphere. So it’s possible that they could produce unrealistic results – for example, forecasting temperature extremes beyond the bounds of nature. And it is unclear how they will perform during highly unusual or unprecedented weather phenomena. </p>
<p>And relying on AI tools can raise <a href="https://doi.org/10.1017/eds.2022.5">ethical concerns</a>. For instance, locations with relatively few weather observations with which to train a machine learning system may not benefit from forecast improvements that are seen in other areas.</p>
<p>Another central question is how best to incorporate these new advances into forecasting. Finding the right balance between automated tools and the knowledge of expert human forecasters has long been a challenge in meteorology. Rapid technological advances will only make it more complicated.</p>
<p>Ideally, AI and machine learning will allow human forecasters to do their jobs more efficiently, spending less time on generating routine forecasts and more on communicating forecasts’ implications and impacts to the public – or, for private forecasters, to their clients. We believe that <a href="https://www.ai2es.org/">careful</a> <a href="https://www.tacc.utexas.edu/-/next-generation-weather-models-cross-the-divide-to-real-world-impact">collaboration</a> between scientists, forecasters and forecast users is the best way to achieve these goals and build trust in machine-generated weather forecasts.</p><img src="https://counter.theconversation.com/content/182498/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Russ Schumacher receives funding from the National Oceanic and Atmospheric Administration for research on applying machine learning to improve forecasts of high-impact weather.</span></em></p><p class="fine-print"><em><span>Aaron Hill receives funding from the National Oceanic and Atmospheric Administration to research machine learning applications that improve high-impact weather forecasts. </span></em></p>Would you trust a weather forecast made by a machine that had learned how weather systems behaved by reviewing thousands of past weather maps?Russ Schumacher, Associate Professor of Atmospheric Science and Colorado State Climatologist, Colorado State UniversityAaron Hill, Research Scientist, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1787672022-03-09T19:08:19Z2022-03-09T19:08:19ZWeather forecasts won’t save us – we must pre-empt monster floods years before they hit<p>Most people’s lives are largely removed from nature. We spend our days in temperature-controlled rooms, immersed in virtual environments. Our cars transport us from underground car parks to our garages in comfort, no matter what the outside conditions. </p>
<p>And when a natural hazard hits, we often rely on technology-driven weather forecasts to understand and avoid the risks.</p>
<p>But now, Southeast Queensland and parts of New South Wales are inundated yet again. Clearly, short-term weather forecasts alone are not enough to protect communities in times like these.</p>
<p>Withstanding natural disasters requires recognising the threat earlier, and enacting the systemic change needed to survive. </p>
<figure class="align-center ">
<img alt="home with flood debris in front" src="https://images.theconversation.com/files/450855/original/file-20220309-25-1b33oq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/450855/original/file-20220309-25-1b33oq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450855/original/file-20220309-25-1b33oq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450855/original/file-20220309-25-1b33oq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450855/original/file-20220309-25-1b33oq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450855/original/file-20220309-25-1b33oq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450855/original/file-20220309-25-1b33oq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Withstanding natural disasters requires recognising the threat earlier.</span>
<span class="attribution"><span class="source">Jason O'Brien/AAP</span></span>
</figcaption>
</figure>
<h2>Living with nature</h2>
<p>The public demands accurate weather forecasts. People want to know how the weather will affect their family, work and social schedules so they can minimise the disruptions.</p>
<p>The technology used to determine future weather conditions is continually being refined. Now, sophisticated computer models churn out 24/7 forecasts and radars provide real-time images of where rain is falling.</p>
<p>But projecting the arrival and behaviour of extreme weather remains challenging.</p>
<p>These events, such as intense rain, can develop and intensify within hours. Short-term forecasts often change throughout the day as conditions develop.</p>
<p>The recent heavy rain and flooding shows how we’re pushing the limits of this technology. It has also exposed vulnerabilities in our collective ability to apply the information generated. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-floods-have-killed-at-least-21-australians-adapting-to-a-harsher-climate-is-now-a-life-or-death-matter-178761">The floods have killed at least 21 Australians. Adapting to a harsher climate is now a life-or-death matter</a>
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<hr>
<figure class="align-center ">
<img alt="woman in rainy street with umbrella" src="https://images.theconversation.com/files/450857/original/file-20220309-15-1bu66qq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/450857/original/file-20220309-15-1bu66qq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450857/original/file-20220309-15-1bu66qq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450857/original/file-20220309-15-1bu66qq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450857/original/file-20220309-15-1bu66qq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450857/original/file-20220309-15-1bu66qq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450857/original/file-20220309-15-1bu66qq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Intense rain can develop within hours.</span>
<span class="attribution"><span class="source">Damian Shaw/AAP</span></span>
</figcaption>
</figure>
<h2>Advancing technologies</h2>
<p>Australia has the <a href="https://media.bom.gov.au/social/blog/1459/how-does-a-weather-radar-work/">fourth-largest</a> weather radar network in the world.</p>
<p>Radars work by emitting electromagnetic waves. When the waves hit an object, such as a water in the atmosphere, the signal bounces back to the radar. This information is then converted into data on a map that can be viewed by the public.</p>
<p>Rain radars tell us where rain is falling, and how heavily. Experts can use this information to infer what the rain might do next. But weather forecasting is not an exact science and, as with any technology, there’s always room for improvement. </p>
<p>For example, changes to coastal temperatures and humidity over small areas, in a short period, can <a href="https://eos.org/science-updates/challenges-and-opportunities-in-coastal-prediction">thwart a forecast’s accuracy</a>.</p>
<p>Forecasters also use weather models – computers that simulate conditions in the atmosphere, ocean, and above land and apply mathematical equations to predict future weather.</p>
<p>Low pressure systems and especially east coast and tropical lows, which can lead to storms, are <a href="https://www.abc.net.au/news/2021-11-04/how-to-interpret-the-bureau-of-meteorology-s-rain-forecast/100580448">harder to predict</a> than high pressure systems which tend to bring calm conditions.</p>
<figure class="align-center ">
<img alt="weather radar image of east coast" src="https://images.theconversation.com/files/450856/original/file-20220309-17-ob3z0f.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/450856/original/file-20220309-17-ob3z0f.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450856/original/file-20220309-17-ob3z0f.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450856/original/file-20220309-17-ob3z0f.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450856/original/file-20220309-17-ob3z0f.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450856/original/file-20220309-17-ob3z0f.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450856/original/file-20220309-17-ob3z0f.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Rain radars tell us where rain is falling and how heavily.</span>
<span class="attribution"><span class="source">BOM</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/all-hail-new-weather-radar-technology-which-can-spot-hailstones-lurking-in-thunderstorms-86856">All hail new weather radar technology, which can spot hailstones lurking in thunderstorms</a>
</strong>
</em>
</p>
<hr>
<h2>Wired to predict</h2>
<p>There is widespread misunderstanding of what rain radars actually tell us. They show what is happening now, and what has just occurred. They do not predict future conditions. </p>
<p>But the human brains is <a href="https://theconversation.com/what-youre-seeing-right-now-is-the-past-so-your-brain-is-predicting-the-present-131913">wired</a> to predict. So people sometimes make assumptions about the trajectory and future intensity of storm cells they see in radar images. </p>
<p>The media can also undermine the credibility of the forecasting system. News reporting of weather events can sometimes be over-dramatised. And the media does not always update its coverage of extreme weather forecasts – for example, not telling the public when a weather warning has been downgraded. </p>
<h2>Just-in-time flood response is risky</h2>
<p>We can’t directly stop natural hazards occurring. But we can try to make communities better able to withstand them.</p>
<p>Relying on just-in-time weather information is a poor substitute for better planning and preparedness.</p>
<p>For months, we’ve known this summer would be wet. But sadly, many in the community did not act on these projections. </p>
<p>A La Niña event occurred in the summer of 2020-21 and brought above-average rain and <a href="https://www.sbs.com.au/news/article/floods-in-australia-among-most-expensive-climate-events-of-2021-report-finds/trmr6gvww">widespread floods</a>. As others <a href="https://theconversation.com/back-so-soon-la-nina-heres-why-were-copping-two-soggy-summers-in-a-row-173684">have noted</a>, since 1958 about half of La Niña events have reoccurred the following year.</p>
<p>So the odds were already in favour of the 2021-22 summer also being wet. And the second La Niña was <a href="https://theconversation.com/back-so-soon-la-nina-heres-why-were-copping-two-soggy-summers-in-a-row-173684">confirmed</a> in November. </p>
<p>But by and large, these indications were not acted upon. </p>
<p>For example, the Queensland government delivers a generic advertising campaign for storm awareness, but it’s not tailored to specific seasonal conditions or <a href="https://www.qbcc.qld.gov.au/get-ready-storm-season">impending events</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/under-resourced-and-undermined-as-floods-hit-south-west-sydney-our-research-shows-councils-arent-prepared-178293">Under-resourced and undermined: as floods hit south-west Sydney, our research shows councils aren't prepared</a>
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<p>As <a href="https://theconversation.com/the-floods-have-killed-at-least-21-australians-adapting-to-a-harsher-climate-is-now-a-life-or-death-matter-178761">reported</a> in The Conversation this week, Australia has a poor record on implementing plans for natural disaster risk reduction. This includes the National Climate Resilience and Adaptation Strategy, released late last year, which contains no new funding and little detail.</p>
<p>At a government agency level, better flood preparedness would involve, among other things, overhauling planning laws to ensure the built environment is resilient to natural hazards.</p>
<p>It would also involve ensuring local councils are <a href="https://theconversation.com/under-resourced-and-undermined-as-floods-hit-south-west-sydney-our-research-shows-councils-arent-prepared-178293">properly resourced</a> to help residents on the ground.</p>
<p>Individuals can also take action to minimise flood damage to their property.</p>
<p>I spent last week cleaning mud from the basement of a large apartment block in Brisbane. The damage showed very clearly which residents had moved or protected valuables in basement areas well in advance of the water, and which had not.</p>
<figure class="align-center ">
<img alt="people scrub walls and floors" src="https://images.theconversation.com/files/450859/original/file-20220309-22-1uoy8sh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/450859/original/file-20220309-22-1uoy8sh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450859/original/file-20220309-22-1uoy8sh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450859/original/file-20220309-22-1uoy8sh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450859/original/file-20220309-22-1uoy8sh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450859/original/file-20220309-22-1uoy8sh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450859/original/file-20220309-22-1uoy8sh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">During the flood clean up, it can become clear who was prepared and who was not.</span>
<span class="attribution"><span class="source">Jono Searle</span></span>
</figcaption>
</figure>
<h2>Back to the future</h2>
<p>The flooding in Queensland comes just a decade or so after the devastating Brisbane floods. </p>
<p>The new disaster is <a href="https://www.abc.net.au/news/2022-03-07/south-east-queensland-flood-disaster-damage-bill-budget/100888958">expected</a> to cost the state’s economy up to A$2.5 billion. Insurance claims on damaged homes and businesses will be close to $1 billion.</p>
<p>Flooding in future is inevitable, especially under climate change which will likely bring more frequent and severe bursts of rain. </p>
<p>Relying on short-term weather forecasts to prepare for such events is deeply unwise. Becoming resilient to natural disasters means preparing weeks, months and years in advance.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/under-resourced-and-undermined-as-floods-hit-south-west-sydney-our-research-shows-councils-arent-prepared-178293">Under-resourced and undermined: as floods hit south-west Sydney, our research shows councils aren't prepared</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/178767/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mark Gibbs is a Non-Executive Director of the Gold Coast Waterways Authority, Green Cross Australia, the Moreton Bay Foundation Foundation and Reef Check Australia</span></em></p>Parts of southeast Australia are inundated yet again. Clearly, short-term weather forecasts are not enough to protect communities in times like these.Mark Gibbs, Leader of the Knowledge to Innovation team, Institute for Future Environments and Science and Engineering Faculty, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1774872022-02-18T15:25:09Z2022-02-18T15:25:09ZStorm Eunice: how forecasters predicted super-strong winds days before it even formed<p>Storm Eunice is in full flow as I write this and has already broken the record for the <a href="https://twitter.com/metoffice/status/1494640157789728770">fastest ever gust</a> recorded in England. Before the wind even really got going here in Reading, where I work as a natural hazard forecaster, I had already watched my wheelie bins fly past my window (I since tied them down).</p>
<p>Comparisons are being made with previous storms, particularly the “<a href="https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/interesting/1990/burns-day-storm---25-january-1990---met-office.pdf">Burns’ Day Storm</a>” of January 1990, which killed dozens of people, and the October 1987 “<a href="https://www.metoffice.gov.uk/weather/learn-about/weather/case-studies/great-storm">Great Storm</a>”. Although less intense, Eunice may be meteorologically similar to the 1987 storm, with the chance of a “<a href="https://theconversation.com/will-we-get-stronger-wind-storms-in-a-warmer-climate-177468">sting jet</a>” – a rare but highly damaging phenomenon caused by a break between the warm and cold fronts in a storm. This allows very fast winds, normally kept high in the atmosphere, to reach the ground and lash the surface like a bullwhip.</p>
<p>In 1987, the BBC weather forecaster Michael Fish was <a href="https://www.bbc.co.uk/news/av/uk-19923565">famously caught out</a> by the severity of the Great Storm. What has really changed since the late 1980s is the quality of our forecasting and warnings. The steady improvement in weather and climate forecasting has been caused by unimaginably more powerful supercomputers, much better scientific understanding of the earth’s natural processes, and better communication of risks and early warnings.</p>
<p>Let’s look at the forecasters’ achievement in the week leading up to Eunice, which hit the UK on Friday 18 February. They had identified – and even named – both Eunice and its immediate predecessor Storm Dudley, on the morning of <a href="https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2022/two-storms-named">Monday 14 February</a>. At that point, scientists knew the conditions were right to create a storm, but didn’t know exactly how big or where it would go. </p>
<p>By Wednesday, there was enough certainty in the forecasts to issue <a href="https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2022/amber-warnings-in-force-for-storms-dudley-and-eunice">weather warnings</a>, telling people to get ready for possible serious disruption. Remember, this is before the storm existed and hadn’t even <a href="https://twitter.com/SimonOKing/status/1493849044023660546?s=20&t=a6dVDEh5qOtpb7vjNIjM5Q">begun to form</a> out in the Atlantic. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1493849044023660546"}"></div></p>
<p>By Thursday, with 24 hours’ notice, it was clear where the storm would be going and that the winds would be extremely strong. This lead to a red warning – meaning “take action now” – for <a href="https://www.bbc.co.uk/news/uk-60417263">parts of south Wales and south-west England</a>. And early on Friday morning, south-east England and London were given red warnings too.</p>
<p>Days before Eunice hit the UK mainland, forecasters knew it would be very dangerous. This was a level of detail and accuracy that was completely missing ahead of the Great Storm, meaning there was no early warning in that case. </p>
<h2>Computers, data, communication</h2>
<p>The improvement in the forecast is partly because of the hugely improved resolution of the supercomputer models. We can now simulate the earth in great detail, in four dimensions (including time). We also just have a better understanding of the science, and how conditions in the sea and air combine to create our weather.</p>
<p>But a very fast computer model can only create a forecast as good as the data you put into it. That’s why our improved array of satellites, aircraft, balloons and good old-fashioned weather stations are critical to getting an accurate picture of what is going on.</p>
<p>The final issue is around communication, which has improved significantly in the past 30 years in the UK, thanks in a great part due to the establishment of the <a href="https://www.metoffice.gov.uk/weather/guides/severe-weather-advice">National Severe Weather Warning Service</a> – the system that sets of yellow, amber and red warnings. </p>
<p>The more recent naming of storms, which began in 2015, also helps. “Dudley” and “Eunice” may sound more like a kindly uncle and aunt, but the evidence shows <a href="https://theconversation.com/storm-doris-giving-dangerous-weather-a-human-name-makes-us-more-wary-says-research-66859">naming storms works</a>. The Great Storm and Burns’ Day Storm were named not by emergency planners in advance, but by the media afterwards.</p>
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<p>This is just one example of how forecasters and authorities need to take into account not just the quality of the science, but also how people respond to it. As we saw during the floods in Germany last summer, the best forecasts in the world are useless <a href="https://theconversation.com/europes-catastrophic-flooding-was-forecast-well-in-advance-what-went-so-wrong-164818">if people don’t believe them</a>, or don’t understand how to act to keep themselves safe. </p>
<p>With Eunice, it has been interesting to see how many local authorities, schools and businesses did almost nothing when the warning was “amber”, but then decided to close when it moved to “red”. I’ve also seen people living in areas covered by the amber warning saying, “Phew – we’ll be OK.” That’s not true – amber areas can see damage and risk to life just as severe as the red areas.</p>
<p>There is still much more we can do to improve warning systems, but let’s realise how far we have come. For now, the best advice is to take the warnings seriously, don’t take risks, and keep yourself and your family safe.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<p class="fine-print"><em><span>Hannah Cloke advises the Environment Agency, the European Centre for Medium-range Weather Forecasts, the Copernicus Emergency Management Service, local and national governments and humanitarian agencies on the forecasting and warning of natural hazards. She is a Council member of the UKRI Natural Environment Research Council, a fellow of the European Centre for Medium-range Weather Forecasts, a fellow of the Centre for Natural Hazards & Disaster Science in Sweden and is also affiliated to Uppsala University in Sweden. Her research is funded by the UKRI Engineering & Physical Sciences Research Council, the UKRI Natural Environment Research Council and the Foreign, Commonwealth & Development Office</span></em></p>Scientists have unimaginably more powerful supercomputers than their predecessors.Hannah Cloke, Professor of Hydrology, University of ReadingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1774682022-02-18T15:22:11Z2022-02-18T15:22:11ZWhy Storm Eunice was so severe – and will violent wind storms become more common?<figure><img src="https://images.theconversation.com/files/447308/original/file-20220218-49159-3yu3uc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5760%2C3837&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Porthcawl Lighthouse in South Wales is buffeted by waves during Storm Eunice's approach.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/waves-start-increase-storm-eunice-gathers-2124985670">Leighton Collins/Shutterstock</a></span></figcaption></figure><p>The UK Met Office has issued two <a href="https://www.independent.co.uk/climate-change/news/storm-eunice-met-office-warning-b2017349.html">red weather warnings</a> in as many months for strong winds. These are the highest threat levels meteorologists can announce, and are the first wind-only red warnings to be issued since 2016’s <a href="https://www.metoffice.gov.uk/weather/warnings-and-advice/uk-storm-centre/storm-gertrude">Storm Gertrude</a>. </p>
<p>So what’s behind the UK’s recent spate of dangerous wind storms? And are these events likely to become more common in future?</p>
<p>Storm Arwen in late November 2021 caused devastation across Scotland, northern England and parts of Wales. Winds of 100mph <a href="https://www.bbc.co.uk/news/uk-59435965">killed three people</a>, <a href="https://www.independent.co.uk/news/uk/home-news/storm-arwen-forests-trees-damage-b1975781.html">ripped up trees</a>, and left <a href="https://news.sky.com/story/storm-arwen-power-restored-to-97-of-homes-but-30-000-face-sixth-day-without-electricity-12483799">9,000 people without power</a> for over a week in freezing temperatures. </p>
<p>The destruction caused by Arwen is still apparent in some areas, and the clean-up from Storm Dudley – which battered eastern England on Wednesday February 16 – is <a href="https://www.theguardian.com/uk-news/2022/feb/17/thousands-left-without-power-as-storm-dudley-wreak-havoc-across-uk">underway</a> at the time of writing.</p>
<p>Now the UK faces Storm Eunice, and its gusts of up to <a href="https://news.sky.com/story/storm-eunice-britons-urged-to-stay-at-home-as-rare-red-weather-warning-issued-12544848">122 miles per hour</a>. Eunice bears a striking similarity to the <a href="https://www.telegraph.co.uk/men/thinking-man/weatherman-michael-fish-missing-great-storm-1987-saw-happened/">“Great Storm” of 1987</a>, which unleashed hurricane-force winds and claimed 22 lives across Britain and France in October of that year. Both are predicted to contain a “<a href="https://news.sky.com/story/what-is-a-sting-jet-and-how-could-it-make-storm-eunice-deadly-12544077">sting jet</a>”: a small, narrow airstream that can form inside a storm and produce intense winds over an area smaller than 100 km.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1494635055955775490"}"></div></p>
<p>Sting jets, which were first discovered in 2003, and likely occurred during <a href="https://theconversation.com/sting-jet-the-mysterious-cause-of-the-1987-great-storms-worst-winds-85620">the Great Storm</a> and Storm Arwen, can last anywhere between one and 12 hours. They are difficult to forecast and relatively rare, but make storms more dangerous.</p>
<p>Sting jets occur in a certain type of <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/extratropical-cyclone">extratropical cyclone</a> – a rotating wind system that forms outside of the tropics. These airstreams form around 5km above the Earth’s surface then descend on the southwest side of a cyclone, close to its centre, accelerating as they do and bringing fast-moving air from high in the atmosphere with them. When they form, they can produce much higher wind speeds on the ground than might otherwise be forecast by studying pressure gradients in the storm’s core alone.</p>
<p>Meteorologists are still working to understand sting jets, but they are likely to have a significant influence on the UK’s weather in a warming climate.</p>
<h2>Windier winters ahead?</h2>
<p>In 1987, the models used for weather forecasts were incapable of representing sting jets, but improvements mean that forecasters predicted Storm Eunice before it had even begun to form in the Atlantic.</p>
<p>Over the past decade, our team at Newcastle University has worked closely with colleagues at the UK Met Office to develop new <a href="https://www.youtube.com/watch?v=m19QM7QHPdU">high-resolution climate models</a> that can simulate sting jets, as well as hail and lightning, to illuminate how extreme weather events might change in a warming climate.</p>
<p>We already know that, as the world warms, <a href="https://www.dw.com/en/german-floods-climate-change/a-58959677#:%7E:text=Burning%2520fossil%2520fuels%2520made%2520the,rapid%2520attribution%2520study%2520has%2520found.&text=The%2520floods%252C%2520which%2520killed%2520more,between%2520July%252012%2520and%252015.">downpours are intensifying</a>. The simple reason is that warmer air can hold more moisture. The UK saw the <a href="https://rmets.onlinelibrary.wiley.com/doi/10.1002/asl.1033">wettest day on record</a> in 2020, already estimated to be 2.5 times more likely because of greenhouse gas emissions. </p>
<p>Our research team’s new high-resolution climate models predict <a href="https://journals.ametsoc.org/view/journals/clim/33/17/jcliD200089.xml">bigger increases in winter rainfall</a> than standard <a href="https://www.gfdl.noaa.gov/climate-modeling/#:%7E:text=of%2520data%2520storage.-,What%2520is%2520a%2520Global%2520Climate%2520Model%253F,to%2520long%252Dterm%2520climate%2520prediction.">global climate models</a> due to a large increase in rainfall from thunderstorms during winter.</p>
<p>We are less certain about how the pattern of extreme wind storms, like Eunice, will change, as the relevant processes are much more complicated. The UK’s recent cluster of winter wind storms is related to a particularly strong <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/polar-vortex">polar vortex</a> creating low pressure in the Arctic, and a faster jet stream – a core of very strong wind high in the atmosphere that can extend across the Atlantic – bringing stormier and very wet weather <a href="https://www.theguardian.com/news/2020/jan/22/how-the-polar-vortex-influences-britain-weather">to the UK</a>. </p>
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<p>A stronger jet stream makes storms more powerful and its orientation roughly determines the track of the storm and where it affects. Some aspects of climate change strengthen the jet stream, leading to <a href="https://www.nature.com/articles/s41561-017-0001-8">more UK wind storms</a>. Other aspects, like the higher rate of warming over the poles compared with the equator, may <a href="https://www.nature.com/articles/s41467-022-28283-y">weaken it</a> and the westerly flow of wind towards the UK.</p>
<p>Our high-resolution models predict <a href="https://link.springer.com/article/10.1007/s00382-021-06011-4">more intense wind storms</a> over the UK as climate change accelerates, with much of this increase coming from storms that develop sting jets. </p>
<p>Projections from global climate models are <a href="https://link.springer.com/article/10.1007/s40641-019-00146-7">uncertain</a> and suggest only small increases in <a href="https://wcd.copernicus.org/preprints/wcd-2021-75/wcd-2021-75.pdf">the number of extreme cyclones</a>. But these models fail to represent sting jets and poorly simulate the processes that cause <a href="https://journals.ametsoc.org/view/journals/clim/33/15/JCLI-D-19-0928.1.xml">storms to build</a>. As a result, these models probably underestimate future changes in storm intensity.</p>
<p>We think that using high-resolution climate models, which can represent important processes like sting jets, alongside information from global models on how large-scale conditions might change, could give a more accurate picture. But the UK isn’t doing enough to prepare for the <a href="https://www.theccc.org.uk/publication/independent-assessment-of-uk-climate-risk/">increasingly severe extreme weather</a> already predicted.</p>
<p>Humanity has a choice in how much warmer the world gets based on the rate at which we reduce greenhouse gas emissions. While more research will confirm if more extreme wind storms will hit the UK in the future, we are certain that winter storms will produce stronger downpours and more rain and flooding when they do occur.</p>
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<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
<br><em><a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeTop">Get a weekly roundup in your inbox instead.</a> Every Wednesday, The Conversation’s environment editor writes Imagine, a short email that goes a little deeper into just one climate issue. <a href="https://theconversation.com/uk/newsletters/imagine-57?utm_source=TCUK&utm_medium=linkback&utm_campaign=Imagine&utm_content=DontHaveTimeBottom">Join the 10,000+ readers who’ve subscribed so far.</a></em></p>
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<p class="fine-print"><em><span>Hayley J. Fowler receives funding from the Natural Environment Research Council. She is a member of the BEIS Science Expert Group and President of the British Hydrological Society. </span></em></p><p class="fine-print"><em><span>Colin Manning receives funding from the Natural Environment Research Council. He also receives support from the UK Met Office as a visiting scientist.</span></em></p>Sting jets are poorly understood, but could have a big influence on Britain’s future winter storms.Hayley J. Fowler, Professor of Climate Change Impacts, Newcastle UniversityColin Manning, Postdoctoral Research Associate in Climate Science, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1757402022-02-01T14:22:23Z2022-02-01T14:22:23ZThe science of weather forecasting: what it takes and why it’s so hard to get right<figure><img src="https://images.theconversation.com/files/442675/original/file-20220126-17-1i0g402.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">IgorZh/Shutterstock</span></span></figcaption></figure><p>Weather forecasting is an important science. Accurate forecasting can help to <a href="https://public.wmo.int/en/media/news/new-study-shows-socio-economic-benefits-of-weather-observations">save lives</a> and minimise property damage. It’s also crucial for agriculture, allowing farmers to track when it’s best to plant or helping them protect their crops. </p>
<p>And it will only become more vital in the coming years. Severe weather events are becoming <a href="https://public.wmo.int/en/media/press-release/weather-related-disasters-increase-over-past-50-years-causing-more-damage-fewer">more frequent and more intense</a> because of climate change and variability.</p>
<p>I am <a href="https://scholar.google.com/citations?hl=en&user=gsHLQ2gAAAAJ&view_op=list_works&sortby=pubdate">a meteorologist</a> with specialities in forecasting weather and climate change – who wants to improve the quality of weather products and their applications to spur socioeconomic development across Africa. Doing so matters: the World Bank has <a href="https://www.worldbank.org/en/news/feature/2017/09/12/improving-weather-forecasts-can-reduce-losses-to-development-in-africa">pointed out</a> that better weather forecasts can bolster the continent’s development. </p>
<p>So, how does forecasting work? What does it take to produce accurate, reliable and timely forecasts? And how can African countries do better on this front?</p>
<h2>A complex process</h2>
<p>Weather forecasting is complex and challenging. The process entails <a href="https://www.weather.gov/car/weatherforecasting">three steps</a>: observation, analysis and communication. </p>
<p>For observation, forecasters work with atmospheric models. These are sets of equations that depict the state of the atmosphere. The models use information on the initial state (observations) of the atmosphere, land and ocean to forecast weather. Data from the models is combined with information drawn from weather stations which are set up at key points across a region or country to give the actual state of the atmosphere. This <a href="https://link.springer.com/chapter/10.1007/978-94-010-0029-1_2">data assimilation</a> produces a better forecast since it optimises forecasters’ understanding of the evolving weather system. </p>
<p>It’s easier to be accurate when giving a short-range forecast – one that covers hours to days – than it is when interpreting long-range (months or seasons) data. The atmospheric system is dynamic; the more time that passes, the less certain forecasters can be of its state.</p>
<p>Technological advances have greatly improved the general quality of weather forecasting. For instance, more observations are possible because of <a href="https://www.earthnetworks.com/resources/weather-facts/automated-weather-stations/">automated weather stations</a>. There’s also been an increase in the use of <a href="https://www.usgs.gov/advanced-research-computing/what-high-performance-computing#:%7E:text=High%20Performance%20Computing%20most%20generally,science%2C%20engineering%2C%20or%20business">high performance computing</a>. This allows for more data storage, faster processing, analysis, and visualisation of incoming data.</p>
<p>These datasets are key in diagnosing past and current weather to create a forecast. Unfortunately, the data observation network (both manual and automated stations) is still poor, especially in developing countries. That’s the result of limited investment into the sector. Forecasters in these countries are forced to use alternative datasets that are not very accurate. </p>
<p>One such alternative dataset is <a href="https://www.ncei.noaa.gov/products/weather-climate-models/numerical-weather-prediction">Numerical Weather Prediction</a>. It uses global deterministic models that are normally not detailed enough to realistically represent <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/how-weather-works/what-is-convection">convection</a> at a local or regional level; forecasters using this data often can’t accurately predict rainfall, especially heavy rain. A lack of access to better historical data also means forecasters struggle to identify when an area’s seasonal rainfall will start and end because they can’t examine trends over years or decades.</p>
<p>It’s these variations in access to data and technology that mean some forecasts are more accurate than others. </p>
<p>Once forecasts have been collated, they are released in various forms. The way that weather products – apps, TV and radio bulletins or website updates – are packaged will differ depending on end users’ needs. Some people, like farmers, may be especially interested in seasonal forecasts and will seek these out. Athletes, for example, are more likely to use portals or services that focus on hourly and daily forecasts. </p>
<p>I would recommend that, whoever you are, you consider seasonal forecasts general information for broad planning purposes. But this should be interpreted together with monthly, weekly and daily forecasts for accuracy’s sake.</p>
<h2>Indigenous knowledge</h2>
<p>Some African countries also use another kind of data for their forecasts: <a href="http://www.unesco.org/new/en/natural-sciences/priority-areas/links/related-information/what-is-local-and-indigenous-knowledge">indigenous ecological knowledge</a>. This entails drawing from communities’ long held knowledge about their environments, and especially about long-term trends and shifts. Such knowledge can be blended with scientific processes during forecasting.</p>
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Read more:
<a href="https://theconversation.com/how-satellites-are-helping-africa-improve-weather-forecasts-45548">How satellites are helping Africa improve weather forecasts</a>
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<p>The <a href="https://nation.africa/kenya/business/seeds-of-gold/weatherman-rainmakers-team-up-to-offer-crop-farmers-accurate-forecast-1178750?view=htmlamp">“rainmakers”</a> from the Nganyi community in western Kenya are a good example. These residents have deep historical knowledge about the area’s climate and weather patterns. They use plants and animals to understand what the weather is doing. They now work with meteorologists from <a href="https://meteo.go.ke/">Kenya’s Meteorological Department</a> to produce seasonal weather forecasts.</p>
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<p>Indigenous knowledge is under threat as the elders who are its custodians are perishing. Vital plants and animals used in their processes are going extinct, too. It would be a great pity if this resource were lost to forecasters. This knowledge plays an important role in local livelihoods and it supports efforts to forecast and make sense of seasonal climate state at local scale.</p>
<h2>Changes coming</h2>
<p>Some of the ways that weather is forecast today may change in the coming years. The <a href="https://public.wmo.int/en">World Meteorological Organisation</a> is encouraging national meteorological services to move from what the weather will <em>be</em> (forecasting weather) to what the weather will <em>do</em> – <a href="https://public.wmo.int/en/resources/bulletin/impact-based-forecasting-and-warning-weather-ready-nations">impact based forecasting-and-warning</a>. </p>
<p>There’s also a push to ensure forecasts reach the people who need them. A number of African countries, among them <a href="https://link.springer.com/chapter/10.1007/978-3-030-61160-6_5">Malawi</a> and <a href="https://www.climate-chance.org/en/best-pratices/participatory-scenario-planning-psp-an-approach-to-translate-seasonal-climate-predictions-into-information-adapted-to-the-local-context/">Chad</a>, have adopted what’s known as Participatory Scenario Planning. This collaborative approach designs and delivers user focused climate information services by taking the co-production process down to the sub-national level. It brings together producers and users of weather and climate information – meteorologists, indigenous knowledge experts, researchers, various sectors of local government, farmers, as well as NGOs and journalists.</p>
<p>Private firms that provide global weather forecasts are also emerging. This is commendable given that they supplement the services of countries with limited resources. But my advice is that, where the national meteorological and hydrological centres have capacity to produce weather forecasts, theirs should be considered first, ahead of those generated by private firms. This is because national bodies’ forecasts are based on the observed historical and observed data which they are custodians of rather than private institutions that rely mainly on model data.</p><img src="https://counter.theconversation.com/content/175740/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Victor Ongoma does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Weather forecasting is complex and challenging. The process entails three steps: observation, analysis and communication.Victor Ongoma, Assistant Professor, Université Mohammed VI PolytechniqueLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1758252022-01-27T19:46:48Z2022-01-27T19:46:48ZWhat is a bomb cyclone? An atmospheric scientist explains<figure><img src="https://images.theconversation.com/files/443016/original/file-20220127-22-1gefps5.jpeg?ixlib=rb-1.1.0&rect=6%2C0%2C1042%2C946&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A bomb cyclone over the U.S. East Coast on Jan. 4, 2017.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/east-coast-bomb-cyclone-seen-by-noaas-goes-16-satellite">NOAA/CIRA</a></span></figcaption></figure><p>A bomb cyclone is a large, intense midlatitude storm that has low pressure at its center, weather fronts and an array of associated weather, from blizzards to severe thunderstorms to heavy precipitation. It becomes a bomb when its central pressure decreases very quickly – by at least 24 millibars in 24 hours. Two famed meteorologists, <a href="https://news.mit.edu/2006/obit-sanders">Fred Sanders</a> and <a href="https://www.mcgill.ca/meteo/facultystaff/gyakum">John Gyakum</a>, gave this pattern its name in a <a href="https://doi.org/10.1175/1520-0493(1980)108%3C1589:SDCOT%3E2.0.CO;2">1980 study</a>. </p>
<p>When a cyclone “bombs,” or undergoes bombogenesis, this tells us that it has access to the optimal ingredients for strengthening, such as high amounts of heat, moisture and rising air. Most cyclones don’t intensify rapidly in this way. Bomb cyclones put forecasters on high alert, because they can produce significant harmful impacts.</p>
<p>The U.S. Eastern Seaboard is one of the <a href="https://doi.org/10.1175/1520-0493(2002)130%3C2188:ECDITS%3E2.0.CO;2">regions where bombogenesis is most common</a>. That’s because storms in the <a href="https://www.merriam-webster.com/dictionary/midlatitudes">midlatitudes</a> – a temperate zone north of the tropics that includes the entire continental U.S. – draw their energy from large temperature contrasts. Along the U.S. East Coast during winter, there’s a naturally potent thermal contrast between the cool land and the warm <a href="https://scijinks.gov/gulf-stream/#">Gulf Stream current</a>. </p>
<p>Over the warmer ocean, heat and moisture are abundant. But as cool continental air moves overhead and creates a large difference in temperature, the lower atmosphere becomes unstable and buoyant. Air rises, cools and condenses, forming clouds and precipitation.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ZfvfIUhJKg0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">UK meteorologist Alex Deakin explains how unstable air causes cumulus clouds to form.</span></figcaption>
</figure>
<p>Intense cyclones also require favorable conditions above the surface. Particularly strong upper-level winds, also known as “jet streaks,” and <a href="https://www.weather.gov/jetstream/longshort">high-amplitude waves</a> embedded within storm tracks can help force air to rise. </p>
<p>When a strong jet streak overlies a developing low-pressure system, it creates a feedback pattern that makes warm air rise at an increasing rate. This allows the pressure to drop rapidly at the center of the system. As the pressure drops, winds strengthen around the storm. Essentially, the atmosphere is trying to even out pressure differences between the center of the system and the area around it.</p>
<p>Weather forecasters are predicting that the northeastern U.S. will be affected by a <a href="https://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdspd">potent winter storm on Jan. 28-30, 2022</a>. Forecast models are calling for a swath of snow from coastal North Carolina northward to Maine.</p>
<p>While precise locations and amounts of snowfall are still uncertain, parts of coastal New England appear most at risk of receiving <a href="https://www.wpc.ncep.noaa.gov/wwd/wssi/wssi.php">8-12 inches or more of heavy accumulating snow</a>. Coupled with winds forecast to be over 50 miles per hour along the coast, the storm is likely to produce blizzard conditions, storm surge, coastal flooding, wind damage and beach erosion. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/trvbHGTDHVg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Bomb cyclones are sometimes called ‘winter hurricanes,’ but they are a different type of storm.</span></figcaption>
</figure>
<p>This storm’s life is expected to begin offshore of the southeast U.S. as a weak low-pressure system. Just 24 hours later, global models predict that its central pressure will drop by 35-50 millibars. </p>
<p>If this storm develops as forecasts predict, aided by winds blowing at over 150 miles per hour in the upper atmosphere, very warm sea surface temperatures just offshore (2-4 degrees Fahrenheit warmer than average), and a highly unstable atmosphere, it will have the critical ingredients for a bomb cyclone. </p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/175825/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Esther Mullens receives funding from the National Science Foundation. </span></em></p>The key ingredients for a storm to undergo bombogenesis are an unstable atmosphere, temperature differences and high-speed winds in the upper atmosphere.Esther Mullens, Assistant Professor of Geography, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1662222021-10-01T12:12:13Z2021-10-01T12:12:13ZMonsoons make deserts bloom in the US Southwest, but climate change is making these summer rainfalls more extreme and erratic<figure><img src="https://images.theconversation.com/files/423923/original/file-20210929-14-jky5f7.jpg?ixlib=rb-1.1.0&rect=34%2C0%2C3888%2C2584&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lightning during a monsoon storm in southern Arizona, Saguaro National Park.</span> <span class="attribution"><a class="source" href="https://photolib.noaa.gov/Collections/National-Weather-Service/Other/emodule/627/eitem/17721">Pete Gregoire, NOAA</a></span></figcaption></figure><p>If you’ve never lived in or visited the U.S. Southwest, you might picture it as a desert that is always hot and dry. But this region experiences a monsoon in the late summer that produces thunderstorms and severe weather, much like India’s famous <a href="https://www.britannica.com/science/Indian-monsoon">summer deluges</a>.</p>
<p>And this year, it generated a lot of rain.</p>
<p>July 2021 was the wettest month since record keeping started at the Tucson, Arizona, airport in 1895, with <a href="https://www.wrh.noaa.gov/twc/monsoon/monsoon.php">8.06 inches</a> (205 millimeters) of rainfall – equivalent to 70% of what the city receives in an average year. This year’s monsoon is the third-wettest ever in Tucson, with <a href="https://www.wrh.noaa.gov/twc/monsoon/monsoon.php">12.80 inches</a> (325 millimeters) of rain.</p>
<p>It was completely the opposite in 2020: Tucson had a <a href="https://www.wrh.noaa.gov/twc/climate/monthly/2020.php">dry “non-soon”, with less than 2 inches of rain</a>. These conditions and <a href="https://www.wrh.noaa.gov/twc/climate/monthly/2020.php">record high temperatures</a> fueled Arizona’s <a href="https://www.azcentral.com/story/news/local/arizona-weather/2021/01/27/2020-was-arizonas-worst-wildfire-seasons-decade/4286395001/">largest wildfire season in a decade</a>, including the <a href="https://tucson.com/news/local/one-year-later-researchers-chart-damage-recovery-from-bighorn-fire/article_b8d9bca0-bfef-11eb-878f-2b4fa4e1ae5c.html">Bighorn Fire</a>, which decimated over 60% of the forest in the Catalina Mountains north of Tucson. </p>
<p>Our monsoon system impacts some 20 million people in the Southwest. As researchers studying <a href="https://scholar.google.com/citations?view_op=list_works&hl=en&user=bV991b0AAAAJ">water</a> and <a href="https://scholar.google.com/citations?user=ERu_i_kAAAAJ&hl=en">climate</a>, we investigate monsoon prediction, which is becoming more complicated due to climate change. Understanding monsoons is critical for educating communities about their <a href="https://storymaps.arcgis.com/stories/a3d5f96dfde449908597a691eda0ef82">benefits and risks</a>, and about how to stay safe from effects like flash flooding.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/5OzJhagG5bQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">During the North American monsoon season, the dry U.S. Southwest can suddenly turn very wet.</span></figcaption>
</figure>
<h2>From dry to wet</h2>
<p>The word <a href="https://www.wrh.noaa.gov/twc/monsoon/monsoon_whatis.php">monsoon</a> comes from the Arabic word mausim, or season. Its most traditional use is to describe the large-scale wind shift into the Indian subcontinent from the ocean that coincides with intense summer rains there. But monsoons also occur in Africa, Australia and South America, as well as in <a href="https://doi.org/10.1175/1520-0477(1997)078%3C2197:TNAM%3E2.0.CO;2">Mexico and the southwestern U.S.</a>.</p>
<p>Monsoonal circulations carry warm, moist air inland from the ocean, which causes rainfall in the summer season. In the Southwest, this pattern starts when an area of high pressure, called a monsoon ridge, builds over the mountainous areas of Mexico and moves toward the western U.S. </p>
<p>In May and June, when the center of the ridge is directly overhead, the Southwest is very hot and dry. Monsoon rains begin when the warm, moist air moves into the region on the southern side of the ridge. The monsoon in Arizona officially begins June 15 and ends Sept. 30, with most rainfall usually occurring in July and August.</p>
<p>The monsoon has been vital to southwestern ecosystems for <a href="https://doi.org/10.1038/s41561-018-0220-7">thousands of years</a>. Many species have evolved and adapted to <a href="https://www.desertmuseum.org/books/nhsd_summer.php">take advantage of monsoon rains</a>. The first storms signal milkweed plants to bloom, attracting butterflies to lay their eggs. <a href="https://www.researchgate.net/publication/325828487_Notes_on_Reproduction_of_Great_Plains_Toads_Anaxyrus_cognatus_Anura_Bufonidae_from_Southerrn_Arizona">Great Plains toads</a> and <a href="https://doi.org/10.1007/s00442-017-3969-2">red-spotted tadpoles</a> start their reproductive cycles in rain-filled puddles. Cactus fruits and <a href="https://news.arizona.edu/story/bug-bonanza-7-big-colorful-critters-try-spot-monsoon-season">insects</a> provide food for hummingbirds, white-winged doves and many other birds and animals.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Flowers in a meadow under blue skies." src="https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/423924/original/file-20210929-16-ncozqx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Wildflowers blooming near Flagstaff, Ariz., on Aug. 26, 2021, during an intense monsoon season.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/SouthwestMonsoon/9170d798fdc7456e991c413d5f2ab373/photo">AP Photo/ Felicia Fonseca</a></span>
</figcaption>
</figure>
<h2>Floods in the desert</h2>
<p>Monsoon thunderstorms occur when clouds develop over mountains during the day, producing rain in the afternoon and early evening. They create unique and severe dangers in the desert environment. </p>
<p>Flash flooding occurs when dry soil can’t quickly absorb short-lived, high-intensity downpours. Washes and arroyos – drainage channels that are dry except during heavy rainstorms – can turn into raging currents within minutes, strong enough to carry away cars and people.</p>
<p>Strong thunderstorms can generate microbursts – strong surface winds that gust near hurricane force. They may also trigger dust storms known as <a href="https://www.britannica.com/science/haboob">haboobs</a> – giant walls of dust a mile or more high that reduce visibility to near zero. </p>
<p>The dry, gusty thunderstorms that herald the beginning of the monsoon can start and spread wildfires. One of these storms ignited the infamous <a href="https://sites.google.com/site/yarnellreport/">Yarnell Hill Fire</a> in June 2013, which killed 19 firefighters. Monsoon rains on fire burn scars can trigger mud and debris flows, compounding the initial wildfire damage.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1420967415618281481"}"></div></p>
<p>The atmospheric circulation pattern in July and August 2021 was <a href="https://doi.org/10.1175/1520-0434(1995)010%3C0763:LSPAWS%3E2.0.CO;2">especially favorable for an active monsoon and severe weather</a> in the Southwest. Most of southern Arizona experienced torrential rains over multiple days and weeks. These storms caused <a href="https://twitter.com/WeatherNation/status/1415415808348639234">flash flooding</a>, <a href="https://twitter.com/WeatherNation/status/1413845467012780035">high winds</a>, <a href="https://twitter.com/lorigraceaz/status/1414045200456978433">dust storms</a>, <a href="https://twitter.com/PriscillaCasper/status/1420913070721835015">mud and debris flows</a> and <a href="https://twitter.com/AsteroidDave/status/1417700968876048389">heavy lightning</a>. Emergency responders carried out <a href="https://twitter.com/TucsonFireDept/status/1428499063771598854">almost 100 swift-water rescues in Tucson</a>. Forecasters <a href="https://climas.arizona.edu/podcast/sept-2021-southwest-climate-podcast-generational-monsoon-over">in Phoenix issued more than 100 flash flood warnings in August</a>.</p>
<p>This year’s record monsoon also brought benefits. It replenished local water supplies throughout Arizona, which is in an <a href="https://twitter.com/DroughtGov/status/1433529357943795712">intensive long-term drought</a>. In the Tucson Basin, the monsoon generated <a href="https://new.azwater.gov/sites/default/files/Tucson%20Model%20Report_No_24_v2_1.pdf">sustained flows in tributaries of the Santa Cruz River</a>, which <a href="https://www.kgun9.com/absolutely-az/understanding-monsoon-and-where-all-the-rainwater-goes">helped to recharge groundwater</a>. Water reserves <a href="https://www.abc15.com/weather/impact-earth/srp-lake-levels-up-thanks-to-wet-monsoon">rose by 5%</a> in reservoirs managed by the Salt River Project, which supplies water to more then 2 million people in central Arizona, at a time when others elsewhere in the West are <a href="https://theconversation.com/as-colorado-river-basin-states-confront-water-shortages-its-time-to-focus-on-reducing-demand-165646">dropping to record lows</a>.</p>
<p>Monsoon rains also brought the Sonoran desert back to life, including areas where the 2020 <a href="https://www.washingtonpost.com/climate-solutions/interactive/2021/saguaro-cactus-climate-change/">Bighorn fire killed thousands of Saguaros</a>. </p>
<h2>The future of the monsoon</h2>
<p>Forecasting the monsoon and how it may change is challenging. High-resolution atmospheric models that explicitly simulate individual thunderstorms, including our <a href="http://www.atmo.arizona.edu/?id=wrf&section=weather">own regional modeling system at University of Arizona</a>, have greatly improved daily weather forecasts in recent decades. But it is still virtually impossible to predict exactly when and where storms will occur on a given day.</p>
<p>It’s also essentially impossible to forecast months in advance how strong monsoon rains will be. This year, long-range forecasts <a href="https://twitter.com/NWSCPC/status/1410313699680690178">didn’t start to trend wet until mid- to late June</a>. Climate change is making monsoon rain more extreme and variable, driven by hotter summers and characterized by <a href="http://dx.doi.org/10.1007/s40641-019-00135-w">less frequent but more intense storms</a>.</p>
<p>If recent years are any indication, our region is already experiencing these effects, with <a href="https://www.climate.gov/news-features/event-tracker/record-breaking-june-2021-heatwave-impacts-us-west">record heat waves</a>, <a href="https://apnews.com/article/ca-state-wire-arizona-fires-wildfires-environment-and-nature-8dcb89fd5ded4c632155c3478d8ba3ee">larger and catastrophic wildfires</a>, and a monsoon that is basically nonexistent one year, then produces record rainfall and severe weather the next. Such shifts are exacerbating people’s exposure to weather and climate extremes in the Southwest. </p>
<p>The big concern is whether a more extreme and erratic monsoon will cause an increase in threshold points of failure – for example, flood control infrastructure that collapses from intense rainfall, or wildfires so devastating that forests can’t recover. Clearly understanding these types of risk is critical to creating a more resilient and sustainable future for the Southwest.</p>
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<p class="fine-print"><em><span>Christopher L. Castro receives funding from the US Department of Defense's Strategic Environmental Research and Development Program.</span></em></p><p class="fine-print"><em><span>Diana Zamora-Reyes does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Monsoons are weather patterns that bring thunderstorms and heavy rains to hot, dry areas when warm, moist ocean air moves inland. They’re challenging to forecast, especially in a changing climate.Diana Zamora-Reyes, PhD Candidate in Hydrology, University of ArizonaChristopher L. Castro, Professor of Hydrology and Atmospheric Sciences, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.