tag:theconversation.com,2011:/ca/topics/tornado-22606/articlesTornado – The Conversation2024-03-04T13:36:31Ztag:theconversation.com,2011:article/2249042024-03-04T13:36:31Z2024-03-04T13:36:31ZTornadoes, wildfires and other disasters tell a story of vulnerability and recovery in America<figure><img src="https://images.theconversation.com/files/579274/original/file-20240301-48072-ldn4z0.jpg?ixlib=rb-1.1.0&rect=0%2C66%2C6300%2C4121&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Recovering after tornadoes, particularly in small towns, has many challenges. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/SevereWeatherMississippi/61b370c8d262411c808d90ce32510603/photo">AP Photo/Julio Cortez</a></span></figcaption></figure><p>People often think of disasters as great equalizers. After all, a tornado, wildfire or hurricane doesn’t discriminate against those in its path. But the consequences for those impacted are not “one-size-fits-all.”</p>
<p>That’s evident <a href="https://www.cnn.com/2024/03/15/weather/indiana-ohio-storm-tornado-damage-friday/index.html">in recent storms</a> and <a href="https://theconversation.com/texas-fires-with-over-1-million-acres-of-grassland-burned-cattle-ranchers-face-struggles-ahead-to-find-and-feed-their-herds-224840">wildfire disasters</a> and in the <a href="https://www.census.gov/newsroom/press-releases/2024/household-pulse-phase-feb22.html">U.S. Census Bureau</a>’s newly released results from its national household surveys showing <a href="https://www.census.gov/programs-surveys/household-pulse-survey/data.html">who was displaced by disasters in 2023</a>.</p>
<p>Overall, the Census Bureau estimates that nearly 2.5 million Americans had to leave their homes because of disasters in 2023, whether for a short period or much longer. However, a closer look at demographics in the survey reveals much more about disaster risk in America and who is vulnerable.</p>
<p>It suggests, <a href="https://www.wiley.com/en-ca/Disasters%3A+A+Sociological+Approach-p-9780745671017">as researchers have also found</a>, that people with the fewest resources, as well as those who have disabilities or have been marginalized, were more likely to be displaced from their homes by disasters than other people.</p>
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<img alt="A woman walking in thigh-deep water crosses a road carrying a large bag. A National Guard truck brought her to the home to retrieve medications four days after the hurricane." src="https://images.theconversation.com/files/579280/original/file-20240301-26-g8s75y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579280/original/file-20240301-26-g8s75y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579280/original/file-20240301-26-g8s75y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579280/original/file-20240301-26-g8s75y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579280/original/file-20240301-26-g8s75y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579280/original/file-20240301-26-g8s75y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579280/original/file-20240301-26-g8s75y.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">Disasters like hurricanes can cut electricity and running water to homes for weeks at a time, and can make access to retrieve medication and belongings for those displaced nearly impossible.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/HurricaneIdaPhotoGallery/2490e0f63dcf439cb612f8c1d2ce1c21/photo">AP Photo/Gerald Herbert</a></span>
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<p>Decades of <a href="https://www.wiley.com/en-ca/Disasters%3A+A+Sociological+Approach-p-9780745671017">disaster research</a>, including from our team at the University of Delaware’s <a href="https://www.drc.udel.edu/">Disaster Research Center</a>, make at least two things crystal clear: First, people’s social circumstances – such as the resources available to them, how much they can rely on others for help, and challenges they face in their daily life – can lead them to experience disasters differently compared to others affected by the same event. And second, <a href="https://www.routledge.com/Social-Vulnerability-to-Disasters/Thomas-Phillips-Lovekamp-Fothergill/p/book/9781466516373">disasters exacerbate</a> existing vulnerabilities.</p>
<p>This research also shows how disaster <a href="https://cup.columbia.edu/book/after-great-disasters/9781558443310">recovery</a> is a <a href="https://doi.org/10.4337/9781839100307.00009">social process</a>. Recovery is not a “thing,” but rather it is linked to how we talk about recovery, make decisions about recovery and prioritize some activities over others.</p>
<h2>Lessons from past disasters</h2>
<p>Sixty years ago, the recovery period after the destructive 1964 Alaskan earthquake was driven by a range of <a href="https://udspace.udel.edu/server/api/core/bitstreams/49cb0325-3638-49ae-9687-3f3ca1aabf1b/content">economic and political interests</a>, not simply technical factors or on need. That kind of influence continues in disaster recovery today. Even disaster buyout programs can be based on <a href="https://doi.org/10.1007/s10584-018-2272-5">economic considerations that burden under-resourced communities</a>.</p>
<p>This recovery process is made even more difficult because <a href="https://doi.org/10.1007/s11069-020-04463-1">policymakers often underappreciate</a> the immense difficulties residents face during recovery.</p>
<p>Following Hurricane Katrina, sociologist Alexis Merdjanoff found that property ownership status <a href="https://doi.org/10.1016/j.ssresearch.2013.04.004">affected psychological distress and displacement</a>, with displaced renters showing higher levels of emotional distress than homeowners. Lack of autonomy in decisions about how to repair or rebuild can play a role, further highlighting disparate experiences during disaster recovery.</p>
<h2>What the Census shows about vulnerability</h2>
<p>The <a href="https://www.census.gov/newsroom/press-releases/2024/household-pulse-phase-feb22.html">2023 census data</a> consistently showed that socially vulnerable groups reported being displaced from their homes at higher rates than other groups.</p>
<p>People over 65 had a higher rate of being displaced than younger people. So did Hispanic and Black Americans, people with less than a high school education and those with low household incomes or who were struggling with employment compared to other groups. While the Census Bureau describes the data as experimental and notes that some sample sizes are small, the differences stand out and are consistent with what researchers have found.</p>
<p>Low-income and marginalized communities are often in areas at higher risk of flooding from storms or may <a href="https://theconversation.com/the-2021-hurricane-season-showed-us-isnt-prepared-as-climate-related-disasters-push-people-deeper-into-poverty-169075">lack investment in storm protection measures</a>.</p>
<p>The morass of bureaucracy and conflicting information can also be a barrier to a swift recovery. </p>
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<img alt="A woman in a polo shirt with a shirt reading " src="https://images.theconversation.com/files/579272/original/file-20240301-20-knv4c3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579272/original/file-20240301-20-knv4c3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579272/original/file-20240301-20-knv4c3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579272/original/file-20240301-20-knv4c3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579272/original/file-20240301-20-knv4c3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579272/original/file-20240301-20-knv4c3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579272/original/file-20240301-20-knv4c3.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">FEMA typically sets up recovery centers near disaster sites to help residents apply for federal aid. But getting to centers like this one near Lahaina, Hawaii, where a fire destroyed much of the town in 2023, can be difficult for people displaced by disasters.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:FEMA_-_7977434.jpg">Department of Homeland Security</a></span>
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<p>After Hurricane Sandy, people in New Jersey complained about complex paperwork and what felt to them like ever-changing rules. They bemoaned their housing recovery as, in researchers’ words, a “<a href="https://doi.org/10.1007/s11069-020-04463-1">muddled, inconsistent experience that lacked discernible rationale</a>”.</p>
<p>Residents who don’t know how to find information about disaster recovery assistance or can’t take time away from work to accumulate the necessary documents and meet with agency representatives can have a harder time getting quick help from federal and state agencies.</p>
<p>Disabilities also affect displacement. Of those people who were displaced for some length of time in 2023, those with significant difficulty hearing, seeing or walking reported being displaced at higher rates than those without disabilities.</p>
<p><a href="https://doi.org/10.1007/s11069-022-05638-8">Prolonged loss of electricity or water</a> due to an ice storm, wildfire or grid overload during a heat emergency can force those with medical conditions to leave even if their neighbors are able to stay. </p>
<p>That can also create challenges for their recovery. Displacement can leave vulnerable disaster survivors isolated from their usual support systems and health care providers. It can also <a href="https://doi.org/10.1193/1.4000116">isolate those with limited mobility</a> from disaster assistance.</p>
<h2>Helping communities build resilience</h2>
<p>Crucial research efforts are underway to better help people who may be struggling the most after disasters.</p>
<p>For example, our center was part of an interdisciplinary team that developed a <a href="https://www.copewellmodel.org/">framework to predict community resilience</a> after disasters and help identify investments that could be made to bolster resilience. It outlines ways to identify gaps in community functioning, like health care and transportation, before disaster strikes. And it helps determine recovery strategies that would have the most impact.</p>
<p>Shifts in weather and climate and a mobile population mean that people’s exposure to hazards are constantly shifting and often increasing. The <a href="https://www.drc.udel.edu/cheer/">Coastal Hazard, Equity, Economic Prosperity, and Resilience Hub</a>, which our center is also part of, is developing tools to help communities best ensure resilience and strong economic conditions for all residents without shortchanging the need to prioritize equity and well-being. </p>
<p>We believe that when communities experience disasters, they should not have to choose among thriving economically, ensuring all residents can recover and reducing risk of future threats. There must be a way to account for all three.</p>
<p>Understanding that disasters affect people in different ways is only a first step toward ensuring that the most vulnerable residents receive the support they need. Involving community members from disproportionately vulnerable groups to identify challenges is another. But those, alone, are not enough.</p>
<p>If we as a society care about those who contribute to our communities, we must find the political and organizational will to act to reduce the challenges reflected in the census and disaster research.</p>
<p><em>This article, originally published March 4, 2024, has been updated with severe storms in mid-March.</em></p><img src="https://counter.theconversation.com/content/224904/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tricia Wachtendorf is co-director of the University of Delaware Disaster Research Center.</span></em></p><p class="fine-print"><em><span>James Kendra is co-director of the University of Delaware Disaster Research Center.</span></em></p>Census data and research show all things are not equal in disaster displacement, as two experts in disaster recovery explain.Tricia Wachtendorf, Professor of Sociology and Director, Disaster Research Center, University of DelawareJames Kendra, Director, Disaster Research Center and Professor, Public Policy & Administration, University of DelawareLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2099212023-10-16T15:38:04Z2023-10-16T15:38:04ZTornadoes in the UK are surprisingly common and no one knows why<p>A small tornado recently passed through the town of Littlehampton on England’s south coast. Strong winds smashed windows, moved cars and left <a href="https://www.dailymail.co.uk/news/article-12530871/Trail-devastation-freak-mini-tornado-hit-West-Sussex-flying-debris-trashing-vehicles-homes-Atlantic-storm-battered-Britain.html">one person injured</a>.</p>
<p>You might associate tornadoes with the plains of the central US, but they’re surprisingly common in the UK too – albeit smaller and weaker. In fact, my former PhD student Kelsey Mulder found that the UK has about 2.3 tornadoes per year per 10,000 square kilometres. That’s a higher density than the US, which as a whole has just 1.3 per 10,000 square km.</p>
<p>The numbers are higher for American states in “Tornado Alley” such as Oklahoma (3.6) or Kansas (11.2). Nonetheless, a random location in the UK is more likely to experience a tornado than a random location in the US. </p>
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<p>The data isn’t perfect, however. Tornadoes cannot be observed by satellites and need to be close to weather radars, which can detect the rotation. Thus, most observations are made by humans who then have to report them to the relevant weather service. “Storm-chasers” follow most tornadoes on the American plains, but underreporting may be an issue elsewhere.</p>
<p>Most tornado research has focused on the US, where forecasting and early-warning systems are advanced. There is considerably less research on UK tornadoes. Over the past 12 years, my research group has tried to address this by shedding light on <a href="https://doi.org/10.1175/MWR-D-14-00299.1">where and when UK tornadoes occur</a>, what causes the <a href="https://doi.org/10.1175/WAF-D-20-0021.1">storms that produce them</a> and how we can <a href="https://doi.org/10.1175/WAF-D-15-0131.1">better predict them</a>.</p>
<h2>England has three ‘tornado alleys’</h2>
<p>Whereas many tornadoes in the US plains occur within a few weeks during the spring, UK tornadoes can occur throughout the year. The UK’s tornado alley is really three regions, most in southern England: an area south of a line between Reading and London with a maximum near Guildford, locations southwest of Ipswich and a line west and south of Birmingham. </p>
<p>These regions have probabilities of experiencing a tornado within a 100 square km area of somewhere between 3% and 6% per year, meaning they could see one as often as every 15 to 30 years.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552505/original/file-20231006-30-nrbxqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="annotated map of UK" src="https://images.theconversation.com/files/552505/original/file-20231006-30-nrbxqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552505/original/file-20231006-30-nrbxqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=729&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552505/original/file-20231006-30-nrbxqv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=729&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552505/original/file-20231006-30-nrbxqv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=729&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552505/original/file-20231006-30-nrbxqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=916&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552505/original/file-20231006-30-nrbxqv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=916&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552505/original/file-20231006-30-nrbxqv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=916&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tornadoes between 1980 and 2012, mapped by Dr. Kelsey Mulder and the author.</span>
<span class="attribution"><a class="source" href="https://journals.ametsoc.org/view/journals/mwre/143/6/mwr-d-14-00299.1.xml">Monthly Weather Review</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>These tornadoes aren’t as violent as the more extreme ones in the US, but the damage can still be substantial. In July 2005, a large tornado in Birmingham caused £40 million in damages and <a href="https://ams.confex.com/ams/pdfpapers/115203.pdf">injured 39</a>. Fortunately, no one was killed. People have died in the past though, for example a strong tornado in South Wales in 1913 <a href="https://www.geologywales.co.uk/storms/1913.htm">killed three</a>.</p>
<p>Although the Birmingham tornado was the most damaging tornado on that day, two others were recorded across the British Isles. Indeed, around 70% of UK tornado days have at least two reports, and 13% produce three or more.</p>
<p>We refer to such days as tornado outbreaks, with the largest-ever UK tornado outbreak occurring on 23 November 1981, producing <a href="https://doi.org/10.1175/WAF-D-15-0131.1">104 tornado reports</a> from Anglesey to Norwich.</p>
<h2>What causes tornadoes</h2>
<p>We still don’t know exactly why the UK has so many weak tornadoes. We do know that “supercells” – rotating thunderstorms tens of kilometres across – form the largest tornadoes in the US but occur less frequently in the UK. Instead, tornadoes in the UK tend to be formed from lines of storms along cold fronts. </p>
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<a href="https://images.theconversation.com/files/552541/original/file-20231006-17-342o3a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Disc shaped storm with lightning." src="https://images.theconversation.com/files/552541/original/file-20231006-17-342o3a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552541/original/file-20231006-17-342o3a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552541/original/file-20231006-17-342o3a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552541/original/file-20231006-17-342o3a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552541/original/file-20231006-17-342o3a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552541/original/file-20231006-17-342o3a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552541/original/file-20231006-17-342o3a.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>
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<span class="caption">The largest tornadoes are formed from supercell storms, like this one in Kansas.</span>
<span class="attribution"><span class="source">GSW Photography / shutterstock</span></span>
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<p>Although millions of dollars have been spent researching supercell thunderstorms in the US, there is an increasing awareness that these linear storms also require investigation on both sides of the Atlantic. Our group has been trying to understand what causes some of these parent storms to begin to rotate and eventually spawn tornadoes. </p>
<p>So far, my former PhD student Ty Buckingham and I have been able to identify certain conditions where the wind direction changes abruptly. In such cases, an instability may develop where small perturbations grow into <a href="https://research.manchester.ac.uk/en/studentTheses/investigating-vortexgenesis-from-quasi-linear-convective-systems-">rotating vortices a kilometre or more across</a>, regularly spaced along the front. Such vortices are thought to be the precursor for tornadoes.</p>
<p>Identifying the conditions for this so-called “horizontal shearing instability” should mean we can better predict when and where the parent storms that produce the tornadoes form. But understanding this instability is not the only answer. Other tornado-producing storms do not appear to be associated with this instability, so we still have more to learn.</p>
<p>The next step is understanding how the tornadoes themselves form. For that, we will need both fortuitous observations of such tornadoes forming close to Met Office radars and powerful computer programs that are able to model the atmosphere down to a scale of tens of meters.</p>
<p>Recent advances in computing and our collaborations with colleagues in engineering may yet reveal the secrets of UK tornadoes. </p>
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<p class="fine-print"><em><span>David Schultz receives funding on this topic from the Natural Environment Research Council (UK) and has received funding from the Risk Prediction Initiative.</span></em></p>Britain doesn’t have huge violent twisters like the US. But it does have lots of little tornadoes.David Schultz, Professor of Synoptic Meteorology, University of ManchesterLicensed 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>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1641899393971265537"}"></div></p>
<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/1882882022-08-21T13:09:27Z2022-08-21T13:09:27ZCanada is witnessing more thunderstorm impacts than ever before<figure><img src="https://images.theconversation.com/files/478611/original/file-20220810-12-362gqa.jpg?ixlib=rb-1.1.0&rect=67%2C89%2C2697%2C1893&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Severe thunderstorms occur in Canada every year, bringing with them large hail, damaging downburst winds, intense rainfall and tornadoes.</span> <span class="attribution"><span class="source">(Shutterstock)</span></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/canada-is-witnessing-more-thunderstorms-than-ever-before" width="100%" height="400"></iframe>
<p>Residents in eastern Ontario are still recovering after a tornado-producing thunderstorm left a <a href="https://uwo.ca/ntp/blog/2022/ntp_damage_survey_results_from_july_24th_tornado_in_eastern_on.html">path of destruction over 55 kilometres long and up to 1,400 metres wide in July</a>.</p>
<p>Such thunderstorms, and the damage they leave behind, can have deep and far-reaching impacts on society and the economy, and they are only increasing. </p>
<p>In Canada, the new normal for yearly insured catastrophic losses has reached $2 billion — a significant increase from the $422 million per year between 1983 and 2008 — and a significant chunk of that is from <a href="http://www.ibc.ca/on/resources/media-centre/media-releases/severe-weather-in-2021-caused-2-1-billion-in-insured-damage">thunderstorm-related severe and extreme weather</a>. </p>
<p>We at the <a href="https://www.uwo.ca/ntp/">Northern Tornadoes Project</a> and the recently launched offshoot — <a href="https://uwo.ca/nhp/">The Northern Hail Project</a> — are often asked whether these severe and extreme weather events are on the rise, and if this has anything to do with manmade climate change? The simple answer is: it’s complicated.</p>
<h2>The difference between severe and extreme</h2>
<p>Severe thunderstorms occur in Canada every year, bringing with them <a href="https://www.canada.ca/en/environment-climate-change/services/types-weather-forecasts-use/public/criteria-alerts.html">large hail, damaging downburst winds, intense rainfall and tornadoes</a>. More rare and of even greater concern are extreme weather events — with their size, intensity or even time of year well beyond what is typically expected based on past observations.</p>
<figure class="align-center ">
<img alt="Long, thin tornado from thunderstorm base to ground" src="https://images.theconversation.com/files/479450/original/file-20220816-2787-dipc7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/479450/original/file-20220816-2787-dipc7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/479450/original/file-20220816-2787-dipc7b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/479450/original/file-20220816-2787-dipc7b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/479450/original/file-20220816-2787-dipc7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/479450/original/file-20220816-2787-dipc7b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/479450/original/file-20220816-2787-dipc7b.jpg?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">
<figcaption>
<span class="caption">Prairie tornado in D'Arcy, Sask. on June 15, 2021.</span>
<span class="attribution"><span class="source">(David Sills)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Extreme weather conditions include tornadoes causing damage rated <a href="https://www.canada.ca/en/environment-climate-change/services/seasonal-weather-hazards/enhanced-fujita-scale-wind-damage.html">EF3-EF5</a> and significant hail of over five centimetres in diameter. Extreme weather can also arise when large hail accompanies downburst winds — increasing the hailstone impact energy — or when a long-lived thunderstorm system results in a <a href="https://www.spc.noaa.gov/misc/AbtDerechos/derechofacts.htm">derecho</a>, which is a cluster of downbursts (and sometimes embedded tornadoes) resulting in intense damage over hundreds of kilometres.</p>
<p>In September 2018, for example, a tornado outbreak in the National Capital Region caused catastrophic damage resulting in over <a href="http://www.ibc.ca/on/resources/media-centre/media-releases/severe-weather-causes-190-million-in-insured-damage-in-2018">$300 million in insured losses</a>. It is also the latest in the year that a tornado outbreak with up to EF3 damage has been recorded in Canada. </p>
<p>In June 2020, Calgary experienced Canada’s first billion-dollar hailstorm and fourth costliest natural disaster on record, with <a href="http://www.ibc.ca/on/disaster/ice">insured losses of $1.3 billion</a>. The derecho in May 2022 that mainly affected southern Ontario took 12 lives, with early <a href="http://www.ibc.ca/on/resources/media-centre/media-releases/derecho-storm-ranks-6th-largest-insured-loss-event-in-canadian-history">estimates of insured losses close to $900 million</a>. And that’s just over the last four years.</p>
<h2>How can we detect these trends?</h2>
<p>Such events and their impacts cannot be adequately assessed and documented using standard operational weather observation platforms such as <a href="https://www.canada.ca/en/environment-climate-change/services/weather-general-tools-resources/radar-overview.html">radar</a> and surface weather stations. </p>
<p>Tornado tracks and <a href="https://www.nssl.noaa.gov/education/svrwx101/hail/">hailswaths</a> are inherently narrow and often pass between stations. Radar can capture some of the key meteorology, but not the impacts on the ground. </p>
<p>Comprehensive storm surveys by weather and engineering experts are required to fully assess and document the meteorology and its physical impacts through what we call an “event-based approach”. In fact, we recently added a <a href="https://profiles.laps.yorku.ca/profiles/jspinney/">social science component</a> to such investigations to better capture the impacts on people and communities. The <a href="https://ntpopendata-westernu.opendata.arcgis.com/">living database</a> that results from these storm surveys can always be updated as new information is discovered.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478396/original/file-20220809-16047-bohate.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map depicting a 2017 tornado outbreak in Québec" src="https://images.theconversation.com/files/478396/original/file-20220809-16047-bohate.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478396/original/file-20220809-16047-bohate.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478396/original/file-20220809-16047-bohate.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478396/original/file-20220809-16047-bohate.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478396/original/file-20220809-16047-bohate.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478396/original/file-20220809-16047-bohate.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478396/original/file-20220809-16047-bohate.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&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 map shows the starting locations and tracks of the 23 tornadoes that occurred during a two-day tornado outbreak in Québec in June 2017.</span>
<span class="attribution"><span class="source">(Lesley Elliott and Liz Sutherland/The Northern Tornadoes Project)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This approach allowed the Northern Tornadoes Project to uncover one of the largest recorded tornado outbreaks in Canadian history — 23 tornadoes over two days in Québec — and increase the <a href="https://doi.org/10.1175/bams-d-20-0012.1">number of tornadoes documented across Canada each year</a>. It has also allowed the new Northern Hail Project to recover and document <a href="https://www.cbc.ca/news/canada/calgary/hailstorm-innisfail-alberta-record-1.6539442">Canada’s largest hailstone on Aug. 1, 2022</a>. </p>
<p>The greater the length and better the quality of a national database of these events, the more likely it is that any severe and extreme storm trends will be detected.</p>
<h2>Some progress has been made</h2>
<p>The tornado data for Southern Ontario is of sufficient length and quality to allow us to begin to look for trends. A <a href="https://doi.org/10.1029/2021GL096483">2022 study</a> found that the annual number of tornadoes recorded there since 1875 has grown substantially. But that is mainly due to an increase in weak tornadoes — ones that might have gone unreported in the past but now fail to escape the attention of the expanding population with consumer-grade cameras at the ready and access to social media for sharing. </p>
<p>The same study found, however, that tornadoes rated F/EF2+ in southern Ontario occurred gradually later in the year since 1875, now peaking in late summer rather than early summer.</p>
<p>Meanwhile, in the U.S., studies have shown that tornadoes may be occurring in bigger clusters and starting to shift eastward – <a href="https://doi.org/10.1038/s41612-018-0048-2">away from the Great Plains and into more populated areas</a>.</p>
<p>In all cases, clear connections to man-made climate change have not yet been established. It is also yet unknown whether extreme storms are changing in ways that are different from severe storms. But it’s still early and research in this area is growing rapidly.</p>
<h2>While storm trends are studied, prepare for increased impacts</h2>
<p>Canadians are recording and sharing images and experiences of severe and extreme storms more than ever before, increasing the documentation of these events. As the population continues to grow and spread out, the damage and losses caused by thunderstorms will continue to grow. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/480108/original/file-20220819-24-8gqndo.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Damaged cars are seen next to the remains of houses damaged by a tornado." src="https://images.theconversation.com/files/480108/original/file-20220819-24-8gqndo.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480108/original/file-20220819-24-8gqndo.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480108/original/file-20220819-24-8gqndo.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480108/original/file-20220819-24-8gqndo.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480108/original/file-20220819-24-8gqndo.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480108/original/file-20220819-24-8gqndo.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480108/original/file-20220819-24-8gqndo.JPG?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">Damage from an EF2 tornado in Barrie, Ont. on July 15, 2021.</span>
<span class="attribution"><span class="source">(Northern Tornadoes Project)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>At the same time, we are learning more about changing storm patterns and possible connections to climate change. Continuing to increase the length and quality of our national severe and extreme storm event database is needed to better understand such changes.</p>
<p>In the meantime, developing adaptation strategies to ensure resiliency and to lessen the impact of inevitable damaging storms is becoming increasingly important. Improving upon building codes and other policies to promote more resilient buildings and communities is urgently needed to better protect the lives and property of Canadians.</p><img src="https://counter.theconversation.com/content/188288/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gregory Kopp receives funding from Institute for Catastrophic Loss Reduction and ImpactWX. </span></em></p><p class="fine-print"><em><span>David Sills receives funding from ImpactWX. </span></em></p><p class="fine-print"><em><span>Julian Brimelow 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>Are severe and extreme weather events on the rise? And does this have anything to do with manmade climate change? The simple answer is: it’s complicated.Gregory Kopp, Professor of Civil Engineering & ImpactWX Chair of Severe Storms Engineering, Western UniversityDavid Sills, Executive Director - Northern Tornadoes Project, Western UniversityJulian Brimelow, Executive Director Northern Hail Project, Western UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1838992022-06-16T12:42:26Z2022-06-16T12:42:26ZThe cheaper we build our buildings, the more they cost after an earthquake, wildfire or tornado<figure><img src="https://images.theconversation.com/files/466669/original/file-20220601-49022-37lmoh.jpg?ixlib=rb-1.1.0&rect=6%2C44%2C4236%2C2785&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Several people were injured and homes destroyed after tornadoes touched down in Barrie, Ont., in July 2021.</span> <span class="attribution"><span class="source">(Duckdave/Wikimedia)</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>A tornado cut a 270-kilometre path through Kentucky in mid-December 2021, killing 80 people, many in their homes or workplaces, and rendering thousands homeless. The incident prompted David Prevatt, a professor of structural engineering at the University of Florida, to write an opinion piece for the <em>Washington Post</em>, reminding Americans that <a href="https://www.washingtonpost.com/outlook/2021/12/27/we-can-build-homes-survive-tornadoes-like-kentucky-suffered-we-just-havent/">new buildings could be tornado proof, but are not</a>.</p>
<p>We are learning similar truths in Canada. Barrie, Ont., struck by a set of tornadoes on July 15, 2021, is still recovering. So too, are those who survived the fires in Fort McMurray, Alta., in 2016, and in Lytton, B.C., in June 2021. It’s the same story following the floods in British Columbia in November 2021 and the <a href="https://london.ctvnews.ca/northern-tornadoes-project-investigating-east-london-for-possible-tornado-1.5915126">derecho that struck Southwestern Ontario in late May</a>, lifting roofs off some buildings and destroying others. </p>
<p>Engineers, architects and builders can design and construct affordable new buildings that can resist tornadoes, floods and wildfires without making the buildings into bunkers. We could also <a href="https://doi.org/10.1177/8755293020944186">design earthquake-resilient buildings</a>, but do not. </p>
<p>I am a structural engineer and an expert in performance-based engineering and catastrophe risk management. I believe the only way to make that happen is to require our building code to minimize society’s total cost to own new buildings. We have always been free to make that happen, but have a rare window now to shape that future, as the nation and code developers urgently respond to the climate crisis. </p>
<h2>Why don’t we build resilient buildings?</h2>
<p>Building-code writers, engineers and others frequently tout the benefits of modern building codes. But new buildings only keep us relatively safe; they’re not disaster proof. Why don’t we build better buildings? Because it would cost a little more. </p>
<p>We build to minimize initial construction costs while maintaining a reasonable degree of safety and avoiding damage where practical, a strategy known as “least-first-cost” construction. We save a small amount on initial construction costs and call the savings “affordability.” </p>
<p>But that kind of affordability is an illusion, like a tantalizingly low sticker price on a flimsy car. Wise car buyers know that the low cost is just the beginning of a series of bills.</p>
<p>In new construction, <a href="https://scholar.colorado.edu/concern/reports/r494vm29h">every dollar saved weaves in $4 or more of future costs to pay for unpredictable catastrophes: severe storms, massive earthquakes and catastrophic wildfires</a>. That future cost is not an if, but a when — or rather a sequence of whens made more frequent and severe by the climate crisis.</p>
<figure class="align-center ">
<img alt="A man in a hat faces a building with a partially collapsed brick wall." src="https://images.theconversation.com/files/468860/original/file-20220614-17290-2dsj01.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468860/original/file-20220614-17290-2dsj01.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468860/original/file-20220614-17290-2dsj01.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468860/original/file-20220614-17290-2dsj01.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468860/original/file-20220614-17290-2dsj01.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468860/original/file-20220614-17290-2dsj01.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468860/original/file-20220614-17290-2dsj01.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">A man looks at a partially collapsed building in the aftermath of Hurricane Ida, on Sept. 4, 2021, in Houma, La.</span>
<span class="attribution"><span class="source">(AP Photo/John Locher)</span></span>
</figcaption>
</figure>
<p>In research for the U.S. Federal Emergency Management Agency and others, my colleagues and I applied simple methods to design buildings to be stronger, stiffer, or above the flood plain than the U.S. building code currently requires. (Canada’s National Building Code is similar.) We found that society would initially pay about one per cent more for new construction, but avoid future losses many times greater, minimising society’s long-term ownership cost.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/contrary-to-popular-belief-eastern-canada-is-more-at-risk-of-earthquakes-than-perceived-167743">Contrary to popular belief, Eastern Canada is more at risk of earthquakes than perceived</a>
</strong>
</em>
</p>
<hr>
<p>Engineers could have used these ideas long ago. If we had, Canada wouldn’t be losing over <a href="http://assets.ibc.ca/Documents/Facts%20Book/Facts_Book/2020/IBC-2020-Facts.pdf">$2 billion annually to natural catastrophes</a>, equivalent to the <a href="https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=3410017501">cost of four days of new construction</a>. </p>
<p>Our losses grow nine per cent every year, like a credit card that gets charged more each month than is repaid. But unlike a credit card bill, nature demands an unpredictable, enormous payment any time it wants, from anywhere in the country. No Canadian community is immune.</p>
<figure class="align-center ">
<img alt="Graphic showing the rate of increase of disaster losses compared to population growth." src="https://images.theconversation.com/files/468557/original/file-20220613-11-jdqh0d.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468557/original/file-20220613-11-jdqh0d.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=546&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468557/original/file-20220613-11-jdqh0d.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=546&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468557/original/file-20220613-11-jdqh0d.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=546&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468557/original/file-20220613-11-jdqh0d.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=686&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468557/original/file-20220613-11-jdqh0d.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=686&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468557/original/file-20220613-11-jdqh0d.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=686&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Canada’s annual disaster losses have grown about nine per cent annually, 10 times faster than population growth.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>We can fix the problem</h2>
<p>Prime Minister Trudeau has committed to bold, fast action on climate change and its associated disasters, and better building codes can be a part of it. We could install <a href="https://www.iclr.org/wp-content/uploads/PDFS/focus-on-backwater-valves.pdf">sewer backflow valves in homes and workplaces</a>, use <a href="https://doi.org/10.4224/40002647">non-combustible siding rather than vinyl in the wildland-urban interface</a> (where the built environment mingles with nature) and install <a href="https://doi.org/10.25810/rxtc-3p87">impact-resistant asphalt shingle roofs in hail country</a>. Engineers have long lists of ready-made solutions both for new buildings and the ones we already have.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tragic-wildfires-will-continue-until-we-rethink-our-communities-107346">Tragic wildfires will continue until we rethink our communities</a>
</strong>
</em>
</p>
<hr>
<p>Building codes created those problems. They aim for safe and maximally affordable construction, and <a href="https://doi.org/10.4224/40002005">ignore long-term ownership cost</a>. We build cheaply but not efficiently.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/468861/original/file-20220614-18-5rs4su.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An aerial photo of a cul-de-sac with debris at the end of each driveway, where houses once stood." src="https://images.theconversation.com/files/468861/original/file-20220614-18-5rs4su.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/468861/original/file-20220614-18-5rs4su.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=832&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468861/original/file-20220614-18-5rs4su.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=832&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468861/original/file-20220614-18-5rs4su.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=832&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468861/original/file-20220614-18-5rs4su.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1045&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468861/original/file-20220614-18-5rs4su.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1045&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468861/original/file-20220614-18-5rs4su.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1045&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 remains of houses in Moore, Okla., following a tornado on May 20, 2013.</span>
<span class="attribution"><span class="source">(AP Photo/Tony Gutierrez)</span></span>
</figcaption>
</figure>
<p>Three fatal tornadoes in 15 years convinced city officials in Moore, Okla., that the national building codes weren’t protecting them. So, they enacted an <a href="https://www.cityofmoore.com/sites/default/files/uploads/city-council/agendas/mon-mar-17-630pm-agenda_9.pdf">ordinance to make new buildings resistant to all but the most severe tornadoes</a>. </p>
<p>Developers warned that the stricter requirements would drive up home prices and that development would dry up or move outside Moore. Neither thing happened. A few years after the ordinance passed, <a href="https://doi.org/10.1016/j.ijdrr.2017.09.040">researchers found no impacts on home prices or development</a>. </p>
<p>Other jurisdictions could do better too, just like Florida did after <a href="https://www.weather.gov/lch/andrew">Hurricane Andrew in 1992</a>. The state leapt ahead of U.S. building codes with <a href="https://doi.org/10.3368/le.94.2.155">its own stricter, more cost-effective code</a>. The <a href="https://fortifiedhome.org/">Insurance Institute for Business and Home Safety developed a voluntary standard</a>, called “Fortified,” that <a href="https://dx.doi.org/10.2139/ssrn.3330193">reduces future losses and more than pays for itself in higher resale value</a>. </p>
<h2>Disaster-resilient buildings that also cost less</h2>
<p>The climate crisis is forcing major energy-efficiency changes to the building code, offering a rare opportunity to fix our growing disaster liability and minimize long-term ownership cost. The update might include these three steps:</p>
<ul>
<li><p>Enact a building code objective to minimize society’s total ownership cost of new buildings. The Canadian Commission on Building and Fire Codes could formalize the principle in the National Building Code of Canada.</p></li>
<li><p>Require code-change requests (proposals people make to the Canadian Commission on Building and Fire Codes for inclusion in the National Building Code) to be accompanied by estimates of added construction costs and benefits in terms of reduced energy use, future repair costs, improved health and life safety outcomes, and other economic effects whose monetary value can be reasonably estimated.</p></li>
<li><p>Limit the freedom of code committees to reject cost-effective code-change requests. </p></li>
</ul>
<p>Such changes will eventually shrink Canada’s disaster credit card balance. While Canada rethinks energy efficiency, it can also tackle the false economy of least-first-cost construction. With slightly greater initial costs, our buildings will be better able to survive disasters and cost less to own in the long run. </p>
<p>With a wiser code, we can have better, safer, more efficient buildings for ourselves, our neighbours, our children and all future Canadians.</p><img src="https://counter.theconversation.com/content/183899/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keith Porter serves as chief engineer with the Institute for Catastrophic Loss Reduction. </span></em></p>Engineers, architects and builders can design and construct affordable new buildings that can resist tornadoes, floods and wildfires, but do not. We have that opportunity now.Keith Porter, Adjunct research professor, civil and environmental engineering, Western UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1793572022-05-02T12:37:24Z2022-05-02T12:37:24ZWhat do tornadoes look like on the inside?<figure><img src="https://images.theconversation.com/files/457168/original/file-20220408-11-604hh6.JPG?ixlib=rb-1.1.0&rect=6%2C3%2C2035%2C1529&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A tornado in Turkey, Texas.</span> <span class="attribution"><span class="source">Jana Houser</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&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"></span>
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>What do tornadoes look like on the inside? – Madison, age 7, Noblesville, Indiana</strong></p>
</blockquote>
<hr>
<p>Scientists really don’t know the answer to this question. There are no visual observations from inside of a tornado, because these storms create very violent and dangerous conditions on the ground. </p>
<p>If we placed cameras in the path of a tornado, they would either be damaged by the strong winds and swirling debris, or become so caked with mud and water that they wouldn’t produce any useful pictures. And of course, it’s not safe for humans to try to observe tornadoes at close range. It’s important to always <a href="https://www.cdc.gov/nceh/features/tornadosafety/index.html">seek shelter when tornado conditions develop</a>. </p>
<p>We do have some ideas about the structure of the inside of tornadoes from instruments called <a href="https://www.nssl.noaa.gov/tools/radar/mobile/">mobile Doppler radars</a>. Scientists can drive these instruments to locations near the tornado, but stop at a safe distance. </p>
<p>The radar sends energy toward the tornado, and when it hits the storm, some of the energy is bounced back. Researchers can analyze that reflected energy to detect important characteristics about the tornado. These include where there is and is not rain within the storm, where there is debris, how fast the winds are, and how these properties change moving away from the center of the tornado toward its outer edges and up vertically through the storm cloud above it. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/jsDcQryQm3Q?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Researchers use mobile radar to study tornadoes and other kinds of storms across the U.S.</span></figcaption>
</figure>
<p>From these radar observations, we have learned that tornadoes usually have a clear area in their centers, or at least a zone that is rain- and debris-free. This area also has intense vertical winds that sometimes are strong enough to suck pavement up from roads. </p>
<p>This clear space is surrounded by a ring of heavy rain and debris that is often moving outward, away from the tornado’s center. That’s because the winds are spinning incredibly fast and creating <a href="https://www.livescience.com/52488-centrifugal-centripetal-forces.html">centrifugal force</a> that pulls these objects away from the middle of the storm. Sometimes areas of heavy rain that are a little farther removed from the tornado spiral inward toward the area of rotation, like the <a href="https://mynasadata.larc.nasa.gov/basic-page/hurricane-dynamics">spiral bands</a> that extend outward from the eye of a hurricane. </p>
<p>Some tornadoes have only <a href="https://en.wikipedia.org/wiki/Tornado#/media/File:F5_tornado_Elie_Manitoba_2007.jpg">one main funnel cloud</a>. Others have <a href="https://www.youtube.com/watch?v=zsyWlak3_6M">multiple small funnels</a> that rotate around each other. There are even tornadoes that <a href="https://www.spc.noaa.gov/faq/tornado/nofunnel.htm">don’t have a funnel cloud at all</a>. As long as winds are rotating in a tight circle all the way from the storm cloud down to the ground, it’s a tornado, even if atmospheric conditions haven’t condensed water vapor in the air into a visible funnel.</p>
<p>Scientists have also learned that many tornadoes don’t actually descend from the cloud to the ground. Rather, they <a href="https://www.al.com/news/huntsville/2015/05/do_tornadoes_actually_form_on.html">form at the ground</a> and quickly build upward – often in less than a minute. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0PgnpaJ4i5I?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Tornadoes can form at the ground before radar detects rotating winds at low levels.</span></figcaption>
</figure>
<p>When that happens, your eyes may fool you if you’re watching for a funnel cloud coming down from the sky. There could already be tornado-strength winds at the surface, even without that funnel cloud. So be careful – when it comes to tornadoes, looks can be deceiving.</p>
<hr>
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<p class="fine-print"><em><span>Jana Houser receives funding from the National Science Foundation. </span></em></p>You can’t photograph the inside of a twister, but radar offers some clues.Jana Lesak Houser, Associate Professor of Geography, Ohio UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1788632022-03-23T17:46:45Z2022-03-23T17:46:45ZTornadoes, climate change and why Dixie is the new Tornado Alley<figure><img src="https://images.theconversation.com/files/450763/original/file-20220308-27-79zxp9.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C6144%2C4074&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The heart of U.S. tornado activity, once Tornado Alley, has shifted eastward.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/noaaphotolib/27906393336/in/gallery-194732561@N07-72157720311063131/">Brent Koops/NOAA Weather in Focus Photo Contest 2015</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><em>Tornadoes and severe storms swept across the South in <a href="https://www.washingtonpost.com/weather/2022/04/05/severe-thunderstorms-tornadoes-south-southeast/">early April</a> 2022, following <a href="https://apnews.com/article/tornadoes-ap-news-alert-florida-a9d5ab5e1479a40a486d436072884181">a deadly and destructive March</a> when <a href="https://www.spc.noaa.gov/climo/online/monthly/2022_annual_summary.html">over 200 tornadoes</a> were reported. The March numbers, still preliminary, would be a record for the month, though detection has also improved. Severe storms have damaged homes from <a href="https://abcnews.go.com/US/killed-severe-weather-spawns-30-tornadoes-states/story?id=83784060">Texas to Florida</a>, and north to <a href="https://www.washingtonpost.com/weather/2022/04/05/severe-thunderstorms-tornadoes-south-southeast/">South Carolina</a> and <a href="https://weather.com/storms/severe/video/tornado-near-savannah-captured-on-video">Georgia</a> in recent weeks. We asked tornado scientist <a href="https://www.researchgate.net/profile/Ernest-Agee">Ernest Agee</a> to explain what causes tornadoes and how the center of U.S. tornado activity has shifted eastward from the traditional Tornado Alley in recent years.</em></p>
<h2>What causes tornadoes?</h2>
<p>Tornadoes start with thunderstorms. Think of the thunderstorm as the parent of the tornado. When atmospheric conditions favor the development of severe storms, tornadoes can form.</p>
<p>The recipe for a tornado requires a few important ingredients: low-level heat and moisture and cold air aloft, coupled with a favorable wind field that increases in speed with height, as well as changes in the wind direction in the lower levels.</p>
<p>The right combination of heat, moisture and wind can develop rotating thunderstorms capable of spinning off a tornado or a tornado family. Thunderstorms capable of spinning off tornadoes typically develop along and ahead of a <a href="https://www.wpc.ncep.noaa.gov/html/fntcodestxt.html">frontal boundary</a> – where warm and cold air masses meet – often accompanied above by a <a href="https://scijinks.gov/jet-stream/">strong jet stream</a>.</p>
<h2>Why do tornado outbreaks seem to be getting more frequent and intense? Is climate change playing a role?</h2>
<p>Studies do show tornadoes getting <a href="https://doi.org/10.1038/s41612-018-0048-2">more frequent, more intense and more likely to come in swarms</a>.</p>
<p>The most intense and longest-lasting tornadoes tend to come from what are known as <a href="https://www.weather.gov/ama/supercell">supercells</a> – powerful rotating thunderstorms. The <a href="https://www.noaa.gov/news/december-2021-tornado-outbreak-explained">December 2021 outbreak, with more than 60 tornadoes</a> that swept across Kentucky and neighboring states, came from a supercell. The <a href="https://www.weather.gov/bmx/event_04272011">2011 outbreak in Alabama</a> was another.</p>
<p>All of this unfolds under the umbrella of global warming. While it’s still <a href="https://theconversation.com/tornadoes-and-climate-change-what-a-warming-world-means-for-deadly-twisters-and-the-type-of-storms-that-spawn-them-173645">hard for climate models to assess</a> something as small as a tornado, they do <a href="https://doi.org/10.1038/s41612-018-0048-2">project increases in severe weather</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/MJJG3-MVz1U?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Forecasting tornadoes. NOAA National Severe Storms Laboratory.</span></figcaption>
</figure>
<p>What’s interesting is that despite that increase, the per capita death toll from tornadoes has <a href="https://doi.org/10.1175/WCAS-D-18-0078.1">actually gone down</a> in the latter half of the past 100 years. So, as bad as these new outbreaks are, science and technology are saving lives at a faster rate than storms are killing people.</p>
<p>Scientists can now anticipate and forecast areas where tornadoes may develop. If you look at NOAA’s <a href="https://www.spc.noaa.gov/products/outlook/">Storm Prediction Center website</a>, you’ll see eight-day outlooks now. That’s based on scientific knowledge and technology able to target where conditions conducive to tornadoes are developing.</p>
<p>People also <a href="https://abc11.com/tornado-warning-severe-weather-alerts-watch-vs-accuweather/5321358/">know what to do now</a> and are more likely to get warnings, and more homes have <a href="https://www.fema.gov/emergency-managers/risk-management/safe-rooms">safe rooms</a> able to withstand a tornado. Social media also plays a big role today. A few years ago, I had a student who was on his family’s farm when he got a text warning that a tornado was coming. He and his family got to safety just before the tornado hit.</p>
<h2>The Southeast seems to be getting a lot more severe storms. Has Tornado Alley shifted?</h2>
<p>In 2016, my students and I published the first paper that clearly showed, statistically, the <a href="https://doi.org/10.1175/JAMC-D-15-0342.1">emergence of another center of tornado activity</a> in the Southeast, centered around Alabama.</p>
<p>Oklahoma still has tornadoes, of course. But the statistical center has moved. Other research since then has <a href="https://doi.org/10.1002/joc.5285">found similar shifts</a>.</p>
<figure class="align-center ">
<img alt="Map of U.S. showing tornado activity greatest from Louisiana through Alabama and north to Tennessee." src="https://images.theconversation.com/files/450797/original/file-20220308-21-1nm6thq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/450797/original/file-20220308-21-1nm6thq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450797/original/file-20220308-21-1nm6thq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450797/original/file-20220308-21-1nm6thq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450797/original/file-20220308-21-1nm6thq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450797/original/file-20220308-21-1nm6thq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450797/original/file-20220308-21-1nm6thq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mean number of days per year with a tornado registering EF1 strength or greater within 25 miles, 1986-2015.</span>
<span class="attribution"><a class="source" href="https://www.spc.noaa.gov/wcm/">NOAA Storm Prediction Center</a></span>
</figcaption>
</figure>
<p>We found a notable decrease in both the total number of tornadoes and days with tornadoes in the traditional Tornado Alley in the central plains. At the same time, we found an increase in tornado numbers in what’s been dubbed Dixie Alley, extending from Mississippi through Tennessee and Kentucky into southern Indiana.</p>
<p>In the Great Plains, drier air in the western boundary of traditional Tornado Alley probably has something to do with the fact that tornadoes are a declining risk in Oklahoma while wildfire risk is growing. </p>
<p>Research by other scientists suggests that the <a href="https://doi.org/10.1175/EI-D-17-0011.1">dry line</a> between the wetter Eastern U.S. and the drier Western U.S., historically around the 100th meridian, has <a href="https://doi.org/10.1175/EI-D-17-0012.1">shifted eastward</a> by <a href="https://news.climate.columbia.edu/2018/04/11/the-100th-meridian-where-the-great-plains-used-to-begin-now-moving-east/">about 140 miles</a> since the late 1800s. The dry line can be a boundary for convection – the rising of warm air and sinking of colder air that can fuel storms.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1506617765347614725"}"></div></p>
<p>While scientists don’t have a full picture of the role climate change may be playing, we can certainly say we live in a warmer climate, and that a warming climate provides many of the ingredients for severe storms.</p>
<p>[<em><a href="https://memberservices.theconversation.com/newsletters/?source=inline-youresmart">Read The Conversation daily by subscribing to our newsletter</a></em>.]</p>
<p><em>This article was updated April 6, 2022, with more severe storms and tornadoes across the South.</em></p><img src="https://counter.theconversation.com/content/178863/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ernest Agee 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>Studies show tornadoes are getting more common and more intense, and they’re shifting eastward to a new tornado hot spot.Ernest Agee, Professor Emeritus of Atmospheric Science, Purdue UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1745652022-01-10T16:25:44Z2022-01-10T16:25:44Z2021’s biggest climate and weather disasters cost the U.S. $145 billion – here’s what climate science says about them in 5 essential reads<figure><img src="https://images.theconversation.com/files/439926/original/file-20220109-34059-orcudc.jpg?ixlib=rb-1.1.0&rect=8%2C24%2C5503%2C3644&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Residents had to be rescued as Hurricane Ida flooded coastal Louisiana in August 2021.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/people-react-as-a-sudden-rain-shower-soaks-them-with-water-news-photo/1234968513">Patrick T. Fallon/AFP via Getty Images</a></span></figcaption></figure><p>The disasters just kept coming in 2021, from Hurricane Ida’s destruction across Louisiana and the Northeast to devastating wildfires in the West and damaging storms, tornadoes and floods. Nearly half the U.S. was in drought, and extreme temperature spikes disrupted power supplies just when people needed cooling or heating most. </p>
<p>In all, the costliest U.S. weather and climate disasters of the year did an estimated <a href="https://www.ncdc.noaa.gov/billions/overview">US$145 billion in damage</a> and claimed at least 688 lives, the National Oceanic and Atmospheric Administration announced on Jan. 10, 2022. </p>
<p>It was the third-most expensive year on record.</p>
<p>2021 was also <a href="https://theconversation.com/ocean-heat-is-at-record-levels-with-major-consequences-174760">one of the hottest</a> years globally and the <a href="https://www.ncei.noaa.gov/news/national-climate-202112">4th hottest year in the U.S.</a> in 127 years of record-keeping. <a href="https://theconversation.com/extreme-heat-waves-in-a-warming-world-dont-just-break-records-they-shatter-them-164919">Not every weather event</a> is caused by global warming, but <a href="https://theconversation.com/ipcc-climate-report-profound-changes-are-underway-in-earths-oceans-and-ice-a-lead-author-explains-what-the-warnings-mean-165588">rising temperatures affect the climate</a> in ways that <a href="https://www.worldweatherattribution.org/western-north-american-extreme-heat-virtually-impossible-without-human-caused-climate-change/">amplify heat waves</a> and droughts and can supercharge storms. Much of that temperature rise <a href="https://www.metoffice.gov.uk/weather/climate-change/causes-of-climate-change">is caused by greenhouse gases accumulating in the atmosphere from burning fossil fuels</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440121/original/file-20220110-19-gmrzgw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of costliest U.S. weather and climate disasters of 2021" src="https://images.theconversation.com/files/440121/original/file-20220110-19-gmrzgw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440121/original/file-20220110-19-gmrzgw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440121/original/file-20220110-19-gmrzgw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440121/original/file-20220110-19-gmrzgw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440121/original/file-20220110-19-gmrzgw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440121/original/file-20220110-19-gmrzgw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440121/original/file-20220110-19-gmrzgw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.ncei.noaa.gov/news/national-climate-202112">NCEI/NOAA</a></span>
</figcaption>
</figure>
<p>As the disasters unfolded, scientists explained the influence of climate change. Here’s what they said about some of the costliest disasters of 2021.</p>
<h2>Extreme rainfall in the east, drought in the west</h2>
<p>One characteristic that stood out during the disasters of 2021 was a sharp precipitation divide in the U.S.: While most of the west was in severe drought or worse, with the dry vegetation fueling fires, much of the eastern half of the country was getting soaked.</p>
<p>Extreme downpours in August triggered flash floods across Tennessee that swept away homes and vehicles and killed 20 people. A few days later, the remnants of Hurricane Ida crossed the country and hit New York City with <a href="https://theconversation.com/hurricane-ida-2-reasons-for-its-record-shattering-rainfall-in-nyc-and-the-northeast-long-after-the-winds-weakened-167252">record-shattering rainfall</a> that submerged subway stations and basement apartments, killing dozens more.</p>
<p>On the other side of the country, damage from the western drought was much harder to calculate. The extreme dryness <a href="https://water.ca.gov/News/News-Releases/2022/Hyatt-Powerplant-at-Oroville-Dam-Resumes-Operation">shut down a key hydroelectric power plant</a> in California for five months, <a href="https://www.fsa.usda.gov/Assets/USDA-FSA-Public/usdafiles/Disaster-Assist/Secretarials/2021-Secretarial-Disasters/ALL_Drought_CY2021.pdf">harmed farms and ranches</a> and led to the first federal <a href="https://theconversation.com/as-colorado-river-basin-states-confront-water-shortages-its-time-to-focus-on-reducing-demand-165646">water use restrictions for the Colorado River</a> as levels dropped in important reservoirs.</p>
<figure class="align-center ">
<img alt="Image of Lake Mead shows intake towers far above the water level and light rock around edges indicate low water." src="https://images.theconversation.com/files/439920/original/file-20220109-13-12ynvgx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439920/original/file-20220109-13-12ynvgx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439920/original/file-20220109-13-12ynvgx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439920/original/file-20220109-13-12ynvgx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439920/original/file-20220109-13-12ynvgx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439920/original/file-20220109-13-12ynvgx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439920/original/file-20220109-13-12ynvgx.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 Hoover Dam intake towers and ‘bathtub ring’ along the edges of the Colorado River’s Lake Mead shows how far the water level has fallen.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/intake-towers-for-water-to-enter-to-generate-electricity-news-photo/1234075907">Patrick T. Fallon/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>Global warming helps <a href="https://theconversation.com/devastating-colorado-fires-cap-a-year-of-climate-disasters-in-2021-with-one-side-of-the-country-too-wet-the-other-dangerously-dry-173402">fuel both kinds of precipitation extremes</a>, Dayton University climate scientist <a href="https://scholar.google.com/citations?user=eUrrnQkAAAAJ&hl=en">Shuang-Ye Wu</a> explained.</p>
<p>“Higher temperature increases evaporation from Earth’s surface, drying out vegetation and soils, which can fuel wildfires. It also increases the atmosphere’s capacity to hold moisture at a rate of about 7% per degree Celsius that the planet warms. With more moisture evaporating, global precipitation is <a href="https://theconversation.com/the-water-cycle-is-intensifying-as-the-climate-warms-ipcc-report-warns-that-means-more-intense-storms-and-flooding-165590">expected to increase</a>, but this increase is not uniform,” Wu wrote.</p>
<p>As the planet warms, wet areas are likely to get wetter, and dry areas drier, she said.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/devastating-colorado-fires-cap-a-year-of-climate-disasters-in-2021-with-one-side-of-the-country-too-wet-the-other-dangerously-dry-173402">Devastating Colorado fires cap a year of climate disasters in 2021, with one side of the country too wet, the other dangerously dry</a>
</strong>
</em>
</p>
<hr>
<h2>No. 1: Hurricane Ida</h2>
<p>Hurricane Ida, which <a href="https://theconversation.com/hurricane-ida-turned-into-a-monster-thanks-to-a-giant-warm-patch-in-the-gulf-of-mexico-heres-what-happened-167029">exploded from a weak hurricane to a Category 4 storm over warm water</a> in the Gulf of Mexico, was the most expensive disaster of 2021, with damage in Louisiana and then in the Northeast <a href="https://www.ncdc.noaa.gov/billions/events/US/2021">estimated at around $75 billion</a>.</p>
<p>University of Miami oceanographer <a href="https://scholar.google.com/citations?user=48fm7gEAAAAJ&hl=en">Nick Shay</a> explained how the storm passed over a large pool of warm water in the Gulf of Mexico that had spun off from the Loop Current. That warm pool’s heat, extending <a href="http://isotherm.rsmas.miami.edu/heat/weba/atlantic.php">down about 480 feet</a>, fueled its strength. </p>
<p>Hurricanes are fueled by warm water, so <a href="https://www.globalchange.gov/browse/indicators/sea-surface-temperatures">warming surface temperatures</a> will have an effect on them. Climate models suggest that Atlantic hurricane <a href="https://nca2018.globalchange.gov/chapter/2/">rainfall and intensity will increase</a>, but there won’t necessarily be more of the storms. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/hurricane-ida-turned-into-a-monster-thanks-to-a-giant-warm-patch-in-the-gulf-of-mexico-heres-what-happened-167029">Hurricane Ida turned into a monster thanks to a giant warm patch in the Gulf of Mexico – here’s what happened</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="Map of surface temperatures" src="https://images.theconversation.com/files/439842/original/file-20220107-17-zfgn1w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439842/original/file-20220107-17-zfgn1w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=660&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439842/original/file-20220107-17-zfgn1w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=660&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439842/original/file-20220107-17-zfgn1w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=660&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439842/original/file-20220107-17-zfgn1w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=829&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439842/original/file-20220107-17-zfgn1w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=829&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439842/original/file-20220107-17-zfgn1w.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=829&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ida’s route to Louisiana passed over very warm water. The scale shows in meters the maximum depth at which temperatures were at least 78 F (26 C), considered a general threshold for hurricanes to develop.</span>
<span class="attribution"><span class="source">University of Miami</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>No. 2: The Texas freeze</h2>
<p>In February, an Arctic blast sent ice, snow and freezing temperatures through the center of the country. In Texas, the cold blast quickly became a human disaster. The cold weather <a href="https://theconversation.com/how-the-texas-electricity-system-produced-low-cost-power-but-left-residents-out-in-the-cold-155527">overwhelmed Texas’ power grid</a>, <a href="https://www.texastribune.org/2021/02/16/natural-gas-power-storm/">freezing components</a> at natural gas plants and slowing natural gas supplies. An estimated <a href="https://uh.edu/hobby/winter2021/">69% of the state lost power</a>, and NOAA counted 226 deaths. State officials have attributed <a href="https://www.dshs.texas.gov/news/updates/SMOC_FebWinterStorm_MortalitySurvReport_12-30-21.pdf">246 deaths</a> to the storm.</p>
<p>That cold wave was the second-most expensive U.S. disaster of 2021, with costs estimated at around $24 billion.</p>
<figure class="align-center ">
<img alt="Shoppers, some bundled up against the cold, wait in line" src="https://images.theconversation.com/files/439844/original/file-20220107-32935-1vp7z4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439844/original/file-20220107-32935-1vp7z4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=414&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439844/original/file-20220107-32935-1vp7z4a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=414&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439844/original/file-20220107-32935-1vp7z4a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=414&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439844/original/file-20220107-32935-1vp7z4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=521&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439844/original/file-20220107-32935-1vp7z4a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=521&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439844/original/file-20220107-32935-1vp7z4a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=521&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Temperatures in Texas plunged into the teens in February 2021, knocking out power for a population unaccustomed to cold.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/customers-wait-in-line-to-enter-frontier-fiesta-on-february-news-photo/1231221869">Thomas Shea / AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>While it may seem counterintuitive, <a href="https://doi.org/10.25923/gcw8-2z06">rapidly warming temperatures in the Arctic</a> can trigger this kind of southward dip of the jet stream, a strong band of winds at the boundary between colder and warmer air. Research by atmospheric scientists <a href="https://scholar.google.com/citations?user=qWV-WIQAAAAJ&hl=en">Mathew Barlow</a> at the University of Massachusetts Lowell and <a href="https://scholar.google.com/citations?user=kc2doosAAAAJ&hl=en">Judah Cohen</a> at MIT <a href="https://theconversation.com/how-arctic-warming-can-trigger-extreme-cold-waves-like-the-texas-freeze-a-new-study-makes-the-connection-166550">shows how that can happen</a> as changes in the Arctic are followed by changes in the stratospheric polar vortex, which are followed by cold waves in North America and Asia. </p>
<p>“Our research reinforces two crucial lessons of climate change: First, the change doesn’t have to occur in your backyard to have a big effect on you. Second, the unexpected consequences can be quite severe,” they wrote.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-arctic-warming-can-trigger-extreme-cold-waves-like-the-texas-freeze-a-new-study-makes-the-connection-166550">How Arctic warming can trigger extreme cold waves like the Texas freeze – a new study makes the connection</a>
</strong>
</em>
</p>
<hr>
<h2>No. 3: Devastating wildfires</h2>
<p>The heat and dryness in the West contributed to more multibillion-dollar disasters. On Dec. 30, when Colorado would normally be blanketed in snow, a wildfire whipped by powerful winds tore through neighborhoods in <a href="https://theconversation.com/devastating-colorado-fires-cap-a-year-of-climate-disasters-in-2021-with-one-side-of-the-country-too-wet-the-other-dangerously-dry-173402">abnormally dry Boulder County</a>. Nearly 1,000 homes and several businesses were destroyed in a matter of hours.</p>
<p>The blaze followed devastating fires in California over the summer. Altogether, damage from the 2021 Western fires was estimated at $10.6 billion.</p>
<figure class="align-center ">
<img alt="Fire moves through a neighborhood, burning around one house and into another." src="https://images.theconversation.com/files/439921/original/file-20220109-17-158cetw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439921/original/file-20220109-17-158cetw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439921/original/file-20220109-17-158cetw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439921/original/file-20220109-17-158cetw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439921/original/file-20220109-17-158cetw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=512&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439921/original/file-20220109-17-158cetw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=512&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439921/original/file-20220109-17-158cetw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=512&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The fires that devastated parts of Boulder County, Colo., were moving so fast officials could do little more than evacuate homes in their path.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/the-marshall-fire-continues-to-burn-out-of-control-on-news-photo/1362007101">RJ Sangosti/MediaNews Group/The Denver Post via Getty Images</a></span>
</figcaption>
</figure>
<p>As rising global temperatures dry out vegetation, forest managers are dealing with increasing wildfire risks and costs. <a href="https://www.redding.com/story/news/local/fires/2021/08/12/how-much-california-spending-put-out-large-wildfires/8099097002/">Fighting huge wildfires</a>, like the Dixie and Caldor fires in California that destroyed much of <a href="https://inciweb.nwcg.gov/incident/7690/">Greenville</a> and <a href="https://inciweb.nwcg.gov/incident/7801/">Grizzly Flats</a> in 2021, depletes funds needed for fire prevention efforts, such as <a href="https://www.gov.ca.gov/wp-content/uploads/2021/08/8.2.21-USDA-letter.pdf">forest thinning and prescribed burns</a>, University of California forest and fire experts <a href="https://scholar.google.com/citations?user=XRht7F0AAAAJ&hl=en">Susan Kocher</a> and <a href="https://celassen.ucanr.edu/Contact_Us/?facultyid=42299">Ryan Tompkins</a> wrote.</p>
<p>“To manage fires in an era of climate change, where drier, hotter weather creates ideal conditions for burning, experts estimate that the area treated for fuels reduction needs to increase by at least an <a href="https://theconversation.com/moving-beyond-americas-war-on-wildfire-4-ways-to-avoid-future-megafires-168898">order of magnitude</a>,” they said.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/moving-beyond-americas-war-on-wildfire-4-ways-to-avoid-future-megafires-168898">Moving beyond America's war on wildfire: 4 ways to avoid future megafires</a>
</strong>
</em>
</p>
<hr>
<h2>What about the tornadoes?</h2>
<p>Tornadoes, like the deadly outbreak that created another multibillion-dollar disaster across Kentucky and nearby states in early December, haven’t been clearly connected to global warming, but climate models <a href="https://theconversation.com/tornadoes-and-climate-change-what-a-warming-world-means-for-deadly-twisters-and-the-type-of-storms-that-spawn-them-173645">can still provide some insight</a>, as Central Michigan University meteorology professor <a href="https://scholar.google.com/citations?user=8gw9cb8AAAAJ&hl=en">John Allen</a> explained.</p>
<figure class="align-center ">
<img alt="A man carries suitcases out of the shell of a splintered house" src="https://images.theconversation.com/files/439922/original/file-20220109-19-1kxs3et.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439922/original/file-20220109-19-1kxs3et.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439922/original/file-20220109-19-1kxs3et.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439922/original/file-20220109-19-1kxs3et.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439922/original/file-20220109-19-1kxs3et.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439922/original/file-20220109-19-1kxs3et.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439922/original/file-20220109-19-1kxs3et.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">Tornadoes ripped a 250-mile path of destruction across Kentucky and neighboring states in December.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/brad-purdy-salvages-items-from-his-home-after-it-was-news-photo/1359229906">Scott Olson/Getty Images</a></span>
</figcaption>
</figure>
<p>“There are certainly signals pointing in the direction of a stormier future,” Allen said, “but how this manifests for tornadoes is an open area of research.”</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tornadoes-and-climate-change-what-a-warming-world-means-for-deadly-twisters-and-the-type-of-storms-that-spawn-them-173645">Tornadoes and climate change: What a warming world means for deadly twisters and the type of storms that spawn them</a>
</strong>
</em>
</p>
<hr>
<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives. It has been updated with NOAA’s disaster map.</em></p><img src="https://counter.theconversation.com/content/174565/count.gif" alt="The Conversation" width="1" height="1" />
A hurricane that wreaked havoc from Louisiana to New York City, the Texas freeze and devastating western wildfires topped NOAA’s list of billion-dollar disasters in 2021.Stacy Morford, Environment + Climate EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1739042021-12-16T06:36:01Z2021-12-16T06:36:01ZHurricane-force wind gusts in Colorado, dust storms in Kansas, tornadoes in Iowa in December – here’s what fueled a day of extreme storms<figure><img src="https://images.theconversation.com/files/437954/original/file-20211216-23-w5ytwd.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1559%2C1059&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A satellite view on the night of Dec. 15, 2021, at the same time tornadoes were reported in Iowa.</span> <span class="attribution"><a class="source" href="https://www.star.nesdis.noaa.gov/GOES/conus.php?sat=G16">NOAA</a></span></figcaption></figure><p><em>Extremely powerful winds swept across a large part of the U.S. on Dec. 15, 2021, <a href="https://twitter.com/NWSSPC/status/1471333229537873924">hitting several states with hurricane-force gusts</a>. Record temperatures helped generate <a href="https://www.desmoinesregister.com/story/weather/2021/12/15/iowa-high-wind-tornado-map-weather-damage-power-outage-updates/8901263002/">tornadoes in Iowa</a>, winds spread <a href="https://twitter.com/NWSWichita/status/1471248332886470657">grass fires</a> and <a href="https://twitter.com/KWCH12/status/1471203794641997826">dust clouds</a> in Kansas, and wind damage was reported from <a href="https://www.thedenverchannel.com/weather/weather-news/see-the-highest-wind-gusts-recorded-during-colorados-wednesday-wind-storm">Colorado</a> through the Midwest. The National Weather Service described it as a “historical weather day” with a “<a href="https://twitter.com/NWS/status/1471117913767743495">never-before-seen storm outlook</a>.” A meteorologist with the service later <a href="https://www.radioiowa.com/2021/12/17/wednesdays-storm-is-derecho-part-two-for-iowa/">said it qualified as a “serial derecho”</a> – the powerful storm had winds over 80 mph but more spread out than the intense <a href="https://theconversation.com/what-is-a-derecho-an-atmospheric-scientist-explains-these-rare-but-dangerous-storm-systems-140319">derecho that hit Iowa in 2020</a>. At least <a href="https://apnews.com/article/tornadoes-iowa-nebraska-storms-kansas-ee9378aae1cb74911e0f9842a01ccaa1">five people died</a> in the storm, the Associated Press reported.</em></p>
<p><em>We asked <a href="https://ge-at.iastate.edu/directory/william-gallus/">atmospheric scientist William Gallus</a>, whose office at Iowa State University was at the heart of the storms, to explain what caused the extreme weather and why it was so unusual.</em></p>
<h2>What happened in the atmosphere to trigger such extreme weather over such a wide area?</h2>
<p>We were seeing very strong winds because of a very powerful disturbance in the <a href="https://www.weather.gov/jetstream/jet">jet stream</a>. That disturbance helped to create a very intense <a href="https://scijinks.gov/high-and-low-pressure-systems/">low-pressure system</a>, which creates strong winds and storms. But the low pressure wasn’t what made this event unusual.</p>
<p>It was unprecedented because an incredible amount of warm air got <a href="https://twitter.com/BMcNoldy/status/1471151049016688640/photo/1">pulled up from the south</a> ahead of the storm.</p>
<p>Here in Iowa, <a href="https://twitter.com/NWSWPC/status/1471307948945285123">temperatures were the hottest</a> they’ve ever been in December, with <a href="https://twitter.com/JerryWVTM13/status/1471221081000267783">temperatures in the mid 70s</a> on Dec. 15, and a very unusual amount of humidity came up with those temperatures. That’s why we were seeing <a href="https://twitter.com/NWSDesMoines/status/1471268524849078280">tornado warnings</a> <a href="https://twitter.com/NWSDesMoines/status/1471265167610572800">across the region</a> – and reports of <a href="https://www.desmoinesregister.com/story/weather/2021/12/15/iowa-high-wind-tornado-map-weather-damage-power-outage-updates/8901263002/">tornado damage</a>. </p>
<p>Tornadoes are <a href="https://twitter.com/capitalweather/status/1471281957569011713">extremely rare in Iowa in December</a>. Minnesota, which had never had a tornado in December, also had tornado warnings and <a href="https://twitter.com/NWSTwinCities/status/1471319877390508036">a possible sighting</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1471258306903687169"}"></div></p>
<p>The wind speeds with this particular system were about as strong as we’ve seen. But it was all of the other weather parameters coming together in December that put this storm system off the scale.</p>
<p>With the warm moist air, we also had thunderstorms, and thunderstorms tend to make the winds even stronger. If you went up 1,000 feet in the sky, you would find it’s much <a href="https://news.stanford.edu/news/2009/june24/high-altitude-winds-062309.html">windier up there</a>. When you have thunderstorms, the rain helps create a current of wind that goes downward, which we call a downdraft. If you have this downdraft, it tends to carry the really strong winds down to the ground. Thunderstorms in the conditions we were seeing could bring winds that could easily get over 80 mph.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-a-derecho-an-atmospheric-scientist-explains-these-rare-but-dangerous-storm-systems-140319">What is a derecho? An atmospheric scientist explains these rare but dangerous storm systems</a>
</strong>
</em>
</p>
<hr>
<h2>Colorado saw wind gusts over 100 mph. What happened there?</h2>
<p>In Colorado, the mountains also help accelerate the wind. </p>
<p>The winds have to rise over the Rocky Mountains. If you get a <a href="https://www.weather.gov/media/lzk/inversion101.pdf">temperature inversion</a>, where the temperature actually starts to go up rather than down as you get higher in the atmosphere just above the top of the mountains, it can act like a lid that traps the momentum of the wind going over the mountains. The wind can’t really spread out, so instead it rushes downward once you’re on the east side of the mountains.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1471158494787108866"}"></div></p>
<p>With anything going downward, gravity accelerates it, just like if you drop a ball from the top of a skyscraper. The <a href="https://manoa.hawaii.edu/exploringourfluidearth/physical/atmospheric-effects/wind-formation">same thing happens to these winds</a>. As they flow down the east face of the Rockies, they accelerate. </p>
<p>When you’re on the leeward side of a mountain range, like Denver and Boulder, winds in those areas can <a href="https://twitter.com/NWSWPC/status/1471226860499525635">get really strong</a> as they’re descending.</p>
<h2>What role does the jet stream play in a storm like this?</h2>
<p>When we get a low-pressure system, it’s because of wiggles that are happening in the <a href="https://www.weather.gov/jetstream/jet">jet steam</a>. We call them troughs in meteorology.</p>
<figure class="align-right ">
<img alt="Image of the jet stream, looking like a wave" src="https://images.theconversation.com/files/437930/original/file-20211216-25-u8aefo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/437930/original/file-20211216-25-u8aefo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437930/original/file-20211216-25-u8aefo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437930/original/file-20211216-25-u8aefo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437930/original/file-20211216-25-u8aefo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437930/original/file-20211216-25-u8aefo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437930/original/file-20211216-25-u8aefo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An visualization of the jet stream.</span>
<span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/3864">Trent L. Schindler/NASA Scientific Visualization Studio</a></span>
</figcaption>
</figure>
<p>If you look at a map showing the jet stream, the jet stream <a href="https://svs.gsfc.nasa.gov/3864">looks like a roller coaster</a> – it oscillates up and down, from north to south. Any time you’re out ahead of one of these troughs, where the jet stream bends down toward the south and then back toward the north, the air must rise out ahead of it, and this results in a low-pressure system. The winds that blow around it can become very strong. </p>
<p>In this case, there was an especially sharp trough in the jet stream, almost in a “V” shape, that intensified the effect. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/o203JXAnSA0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">What is the jet stream?</span></figcaption>
</figure>
<h2>Is there a connection between this storm and the deadly tornadoes that hit Kentucky and other states on Dec. 10-11?</h2>
<p>It’s hard to say if there was one trigger somewhere on the planet that managed to create these two different ripples in the jet stream.</p>
<p>What’s interesting is that there is <a href="https://www.climate.gov/news-features/blogs/enso/december-2021-la-ni%C3%B1a-update-visual-aids">La Niña going on in the Pacific Ocean</a>. When we have La Niña conditions, we often find that the far northern part of the United States ends up colder than normal and the south ends up warmer, so you have this bigger contrast in temperatures than normal and it often leads to a stronger jet stream.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tornadoes-and-climate-change-what-a-warming-world-means-for-deadly-twisters-and-the-type-of-storms-that-spawn-them-173645">Tornadoes and climate change: What a warming world means for deadly twisters and the type of storms that spawn them</a>
</strong>
</em>
</p>
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<p><em>This article was updated with a National Weather Service meteorologist describing the storm as a “serial derecho.”</em></p><img src="https://counter.theconversation.com/content/173904/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>William Gallus 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>Forecasters described it as a ‘historical weather day.’ An atmospheric scientist who was at the heart of the storms explains what happened.William Gallus, Professor of Atmospheric Science, Iowa State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1737412021-12-15T13:26:04Z2021-12-15T13:26:04ZCellphone bans in the workplace are legal and more common among blue-collar jobs – they also might be a safety risk<figure><img src="https://images.theconversation.com/files/437600/original/file-20211214-19-10it31l.jpg?ixlib=rb-1.1.0&rect=7%2C28%2C4662%2C3052&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Six died as a tornado tore through an Amazon fulfillment center in Edwardsville, Illinois.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/MidwestTornadoes/1dd7219b37b3409aaf5e82755ec0a009/photo?Query=amazon%20tornado&mediaType=photo&sortBy=arrivaldatetime:desc&dateRange=Anytime&totalCount=18&currentItemNo=0">AP Photo/Jeff Roberson</a></span></figcaption></figure><p>Cellphones in the workplace can be a distraction – but they <a href="https://www.cnn.com/2019/05/29/us/weather-alert-tech-saved-lives-trnd/index.html">could also save your life</a>.</p>
<p>In the aftermath of a <a href="https://www.reuters.com/world/us/injuries-reported-after-roof-collapse-amazon-warehouse-illinois-ap-2021-12-11/">devastating tornado ripping through an Amazon warehouse</a> in Edwardsville, Illinois, on Dec. 10, 2021 – killing six employees – the online retailer is reportedly <a href="https://www.bloomberg.com/news/articles/2021-12-13/amazon-rethinks-warehouse-cell-phone-ban-in-wake-of-tornado?sref=Hjm5biAW">reviewing its policy</a> over mobile phone bans during working hours.</p>
<p>Prior to the coronavirus pandemic, it was common for Amazon to require its employees to leave phones at home or in vehicles before setting foot on the factory floor. The policy was <a href="https://www.bloomberg.com/news/articles/2021-12-13/amazon-rethinks-warehouse-cell-phone-ban-in-wake-of-tornado">relaxed during the pandemic</a> but was due to be reintroduced in January. Amazon has indicated that <a href="https://sports.yahoo.com/amazon-refuted-reports-cell-phone-191010716.html">a ban was not in effect</a> at the factory at the time the tornado hit, although some employees have suggested <a href="https://www.bloomberg.com/news/articles/2021-12-13/amazon-rethinks-warehouse-cell-phone-ban-in-wake-of-tornado?sref=Hjm5biAW">Amazon had reinstated the ban elsewhere</a>.</p>
<p>Speaking to Bloomberg, workers at an Amazon warehouse close to the Edwardsville plant said the <a href="https://www.bloomberg.com/news/articles/2021-12-12/deadly-collapse-at-amazon-warehouse-puts-spotlight-on-phone-ban">tornado deaths underscored the need to access phones</a> during emergencies – for example, to obtain information about potentially deadly storms or to help guide rescuers to where people might be trapped. </p>
<p>“If they institute the no-cellphone policy, I am resigning,” said one.</p>
<p>This isn’t the first time that the issue of cellphone bans in the workplace has come up as a safety concern. After a mass shooting at a FedEx center in Indianapolis in April 2021, the company faced <a href="https://www.indystar.com/story/news/local/2021/04/18/fedex-shooting-indianapolis-cell-phone-policy/7251674002/">questions about its ban on cellphones</a>. Not having a cellphone handy could mean you are unable to relay crucial information about an active shooter’s location to authorities.</p>
<p>As an <a href="https://www.stcl.edu/about-us/faculty/richard-r-carlson/">expert on employment law</a>, I know that bans on employees using cellphones are relatively common in workplaces such as factories, farms and fast-food chains. Such employer rules are legal, and there is relatively little that employees can do about it.</p>
<p>In the American workplace, the employer is the manager and controls the conditions of your employment. As such, employees are expected to abide by the employer’s rules.</p>
<p>Employers adopt cellphone bans for a number of reasons, including the perceived negative impact of their use on productivity, <a href="https://www.forbes.com/sites/forbestechcouncil/2020/02/25/employee-smartphones-to-ban-or-not-to-ban/?sh=1d9ff80a1fac">security and privacy</a>.</p>
<p>There are some laws that limit what the employer can do. For example, the <a href="https://www.dol.gov/agencies/whd/flsa">Fair Labor Standards Act</a> limits an employer’s restrictions on hourly wage-earning employees’ personal activity, including cellphone use during time the employer treats as “off the clock.” If an employer limits personal activities such as cellphone use during extended breaks or lunch periods, it might have to “count” that time as “working time” for purposes of overtime pay. </p>
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<p>But no law prohibits the employer from banning phone use or possession during actual work time or in a regular active working area. In fact, an employer can regulate a lot of the things you can bring into a work area. An employer might stipulate that you can’t bring a gun, jewelry or TV into a work area. And breaking such rules can lead to disciplinary measures or even termination. </p>
<p>The <a href="https://www.nlrb.gov/guidance/key-reference-materials/national-labor-relations-act">National Labor Relations Act</a> is one law that limits how far an employer can go in restricting cellphone possession around the workplace under some circumstances. In fact, the right of employers to ban cellphones in the workplace was recently addressed by the <a href="https://www.nlrb.gov/case/16-CA-181144">National Labor Relations Board, which is the agency that interprets the act</a>. In a 2020 ruling, the board upheld a rule adopted by Cott Beverages to limit cellphone use and possession.</p>
<p>The board approved the rule because Cott Beverages did not ban employees from storing their cellphones in lockers or using their phones in non-working areas such as break rooms and outside actual working time. A complete ban on cellphones probably would have violated the National Labor Relations Act, in the board’s view, because it would have <a href="https://www.natlawreview.com/article/nlrb-policy-prohibiting-personal-cell-phones-work-areas-due-to-safety-concerns-may#google_vignette">interfered with the ability of employees to engage</a> in union activity and related organizational activity.</p>
<p>There is little empirical research on what proportion of U.S. employees are subjected to cellphone restrictions. But from my observation, such restrictions generally affect factory workers or others who receive hourly wages rather than white-collar salaried employees.</p>
<p>Nonetheless, the devastating effects of the Edwardsville storm will up the pressure on employers to allow employees to keep hold of their phones, if only for their own safety.</p><img src="https://counter.theconversation.com/content/173741/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Carlson 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>The deaths of six Amazon employees at a factory hit by a tornado raises concerns over prohibitions on cellphones for workers.Richard Carlson, Professor of Law, South Texas College of Law HoustonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1736452021-12-13T20:00:08Z2021-12-13T20:00:08ZTornadoes and climate change: What a warming world means for deadly twisters and the type of storms that spawn them<figure><img src="https://images.theconversation.com/files/437042/original/file-20211212-97168-1sdkrw6.JPG?ixlib=rb-1.1.0&rect=0%2C13%2C2959%2C1845&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tornadoes are hard to capture in climate models.</span> <span class="attribution"><a class="source" href="https://www.noaa.gov/stories/story-map-inside-tornado-alley">Mike Coniglio/NOAA/NSSL</a></span></figcaption></figure><p>The deadly tornado outbreak that tore through communities from Arkansas to Illinois on the night of Dec. 10-11, 2021, was so unusual in its duration and strength, particularly for December, that a lot of people including the U.S. president are <a href="https://www.whitehouse.gov/briefing-room/speeches-remarks/2021/12/11/remarks-by-president-biden-on-the-severe-weather-that-impacted-several-u-s-states/">asking what role climate change might have played</a> – and whether tornadoes will become more common in a warming world.</p>
<p>Both questions are easier asked than answered, but research is offering new clues.</p>
<p>I’m an <a href="https://scholar.google.com/citations?user=8gw9cb8AAAAJ&hl=en">atmospheric scientist</a> who studies severe convective storms like tornadoes and the influences of climate change. Here’s what scientific research shows so far.</p>
<h2>Climate models can’t see tornadoes yet – but they can recognize tornado conditions</h2>
<p>To understand how rising global temperatures will affect the climate in the future, scientists use complex computer models that characterize the whole Earth system, from the Sun’s energy streaming in to how the soil responds and everything in between, year to year and season to season. These models solve millions of equations on a global scale. Each calculation adds up, requiring far more computing power than a desktop computer can handle.</p>
<p>To project how Earth’s climate will change through the end of the century, we currently have to use a broad scale. Think of it like the zoom function on a camera looking at a distant mountain. You can see the forest, but individual trees are harder to make out, and a pine cone in one of those trees is too tiny to see even when you blow up the image. With climate models, the smaller the object, the harder it is to see.</p>
<p>Tornadoes and the severe storms that create them are far below the typical scale that climate models can predict.</p>
<p>What we can do instead is look at the large-scale ingredients that make conditions ripe for tornadoes to form.</p>
<figure class="align-center ">
<img alt="A woman stands in the back of truck working on a LiDAR system" src="https://images.theconversation.com/files/437043/original/file-20211212-172173-6rz92o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437043/original/file-20211212-172173-6rz92o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437043/original/file-20211212-172173-6rz92o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437043/original/file-20211212-172173-6rz92o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437043/original/file-20211212-172173-6rz92o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437043/original/file-20211212-172173-6rz92o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437043/original/file-20211212-172173-6rz92o.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">A researcher with NOAA and the Oklahoma Cooperative Institute prepares a light detection and ranging system to collect data at the edge of a storm.</span>
<span class="attribution"><a class="source" href="https://www.noaa.gov/stories/story-map-inside-tornado-alley">Mike Coniglio/NOAA NSSL</a></span>
</figcaption>
</figure>
<p>Two key ingredients for severe storms are (1) energy driven by warm, moist air promoting strong updrafts, and (2) changing wind speed and direction, known as <a href="https://www.weather.gov/jetstream/tornado">wind shear</a>, which allows storms to become stronger and longer-lived. A third ingredient, which is harder to identify, is a trigger to get storms to form, such as a really hot day, or perhaps a cold front. Without this ingredient, not every favorable environment leads to severe storms or tornadoes, but the first two conditions still make severe storms more likely.</p>
<p>By using these ingredients to characterize the likelihood of severe storms and tornadoes forming, climate models can tell us something about the changing risk.</p>
<h2>How storm conditions are likely to change</h2>
<p>Climate model projections for the United States suggest that the overall <a href="https://doi.org/10.1073/pnas.1307758110">likelihood of favorable ingredients</a> <a href="https://doi.org/10.1175/JCLI-D-14-00382.1">for severe storms</a> <a href="https://doi.org/10.1175/JCLI-D-16-0885.1">will increase</a> <a href="https://doi.org/10.1029/2021EF002277">by the end of the 21st century</a>. The main reason is that warming temperatures accompanied by increasing moisture in the atmosphere increases the potential for strong updrafts.</p>
<p>Rising global temperatures are driving significant changes for seasons that we traditionally think of as rarely producing severe weather. Stronger increases in warm humid air <a href="https://theconversation.com/why-the-southern-us-is-prone-to-december-tornadoes-173643">in fall, winter and early spring</a> mean there will be more days with favorable severe thunderstorm environments – and when these storms occur, they have the potential for greater intensity. </p>
<h2>What studies show about frequency and intensity</h2>
<p>Over smaller areas, we can simulate thunderstorms in these future climates, which gets us closer to answering whether severe storms will form. <a href="https://doi.org/10.1007/s10584-014-1320-z">Several studies</a> have <a href="https://doi.org/10.1175/JCLI-D-16-0885.1">modeled changes</a> to the <a href="https://doi.org/10.1007/s00382-017-4000-7">frequency of intense storms</a> to better understand this change to the environment.</p>
<p>We are already seeing evidence in the past few decades of shifts toward conditions more favorable for severe storms in the cooler seasons, while the summertime likelihood of storms forming is decreasing.</p>
<figure class="align-center ">
<img alt="Destruction of buildings for blocks after the tornado hit Mayfield." src="https://images.theconversation.com/files/437299/original/file-20211213-13-1c8xtd8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437299/original/file-20211213-13-1c8xtd8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437299/original/file-20211213-13-1c8xtd8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437299/original/file-20211213-13-1c8xtd8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437299/original/file-20211213-13-1c8xtd8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437299/original/file-20211213-13-1c8xtd8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437299/original/file-20211213-13-1c8xtd8.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 December tornadoes destroyed homes and buildings in communities from Arkansas to Illinois and claimed dozens of lives, including people in Mayfield, Ky.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/in-this-aerial-view-homes-and-businesses-are-destroyed-news-photo/1358478141">Scott Olson/Getty Images</a></span>
</figcaption>
</figure>
<p>For tornadoes, things get trickier. Even in an otherwise spot-on forecast for the next day, there is no guarantee that a tornado will form. Only a small fraction of the storms produced in a favorable environment will produce a tornado at all.</p>
<p>Several simulations have explored what would happen if a <a href="https://doi.org/10.1175/WAF-D-19-0240.1">tornado outbreak</a> or a tornado-producing storm occurred at different levels of global warming. Projections suggest that <a href="https://doi.org/10.1175/JCLI-D-15-0623.1">stronger, tornado-producing storms</a> may be more likely as global temperatures rise, though strengthened less than we might expect from the increase in available energy.</p>
<h2>The impact of 1 degree of warming</h2>
<p>Much of what we know about how a warming climate influences severe storms and tornadoes is regional, chiefly in the United States. Not all regions around the globe will see changes to severe storm environments at the same rate.</p>
<p>In a <a href="https://doi.org/10.1029/2021EF002277">recent study</a>, colleagues and I found that the rate of increase in severe storm environments will be greater in the Northern Hemisphere, and that it increases more at higher latitudes. In the United States, our research suggests that for each 1 degree Celsius (1.8 F) that the temperatures rises, a 14-25% increase in favorable environments is likely in spring, fall and winter, with the greatest increase in winter. This is driven predominantly by the increasing energy available due to higher temperatures. Keep in mind that this is about favorable environments, not necessarily tornadoes.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/LT7yRMLAkCY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>What does this say about December’s tornadoes?</h2>
<p>To answer whether climate change influenced the likelihood or intensity of tornadoes in <a href="https://www.washingtonpost.com/nation/interactive/2021/tornado-map-quadstate/">the December 2021 outbreak</a>, it remains difficult to attribute any single event like this one to climate change. Shorter-term influences like the <a href="https://www.climate.gov/news-features/blogs/enso/tornados-and-la-ni%C3%B1a-2021-edition">El Niño-Southern Oscillation</a> may also complicate the picture. </p>
<p>There are certainly signals pointing in the direction of a stormier future, but how this manifests for tornadoes is an open area of research.</p>
<p>[<em>Over 140,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-140ksignup">Sign up today</a>.]</p><img src="https://counter.theconversation.com/content/173645/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Allen receives funding from the National Science Foundation (Grant No. AGS-1945286). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.</span></em></p>Climate models can’t see tornadoes, but they can recognize the conditions for tornadoes to form. An atmospheric scientist explains what that means for forecasting future risks.John Allen, Associate Professor of Meteorology, Central Michigan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1736432021-12-12T17:58:03Z2021-12-12T17:58:03ZWhy the southern US is prone to December tornadoes<figure><img src="https://images.theconversation.com/files/437021/original/file-20211211-141178-bawm7m.jpg?ixlib=rb-1.1.0&rect=8%2C17%2C2986%2C1976&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Damage in Mayfield, Kentucky, after a tornado swept through the area on Dec. 11, 2021.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/heavy-damage-is-seen-downtown-after-a-tornado-swept-through-news-photo/1237160787">Brett Carlsen/Getty Images</a></span></figcaption></figure><p><em>On the night of Dec. 10-11, 2021, an outbreak of powerful tornadoes tore through parts of Arkansas, Mississippi, Missouri, Kentucky, Tennessee and Illinois, killing <a href="https://www.washingtonpost.com/national/deadly-tornadoes-leave-path-of-destruction-across-six-states-its-unlike-anything-ive-ever-seen/2021/12/11/6a143b2c-5acc-11ec-b0c0-fe531874605a_story.html">dozens of people</a> and leaving wreckage over hundreds of miles. Hazard climatologists <a href="https://scholar.google.com/citations?user=BZn_vToAAAAJ&hl=en">Alisa Hass</a> and <a href="https://scholar.google.com/citations?user=LvpAEa0AAAAJ&hl=en">Kelsey Ellis</a> explain the conditions that generated this event – including what may be the first “quad-state tornado” in the U.S. – and why the Southeast is vulnerable to these disasters year-round, especially at night.</em></p>
<h2>What factors came together to cause such a huge outbreak?</h2>
<p>On Dec. 10, a powerful storm system approached the central U.S. from the west. While the system brought heavy snow and slick conditions to the colder West and northern Midwest, the South was enjoying <a href="https://twitter.com/NWSLittleRock/status/1469653710867509249/photo/1">near-record breaking warmth</a>, courtesy of warm, moist air flowing north from the Gulf of Mexico. </p>
<p>The storm system ushered in cold, dense air to the region, which interacted with the warm air, creating <a href="https://www.actionnews5.com/2020/01/31/breakdown-why-instability-is-blame-thunderstorms/">unstable atmospheric conditions</a>. When warm and cold air masses collide, less dense warm air rises upward into cooler levels of the atmosphere. As this warm air cools, the moisture that it contains condenses into clouds and <a href="https://scied.ucar.edu/learning-zone/storms/thunderstorms">can form storms</a>.</p>
<p>When this instability combines with significant <a href="https://www.weather.gov/ilx/swop-springtopics">wind shear</a> – winds shifting in direction and speed at different heights in the atmosphere – it can create an ideal setup for strong rotating storms to occur. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bFtWlWQk95Q?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Atmospheric instability develops when air is warm at the surface and cold at higher levels. This causes parcels of warm air to rise and form clouds that can produce thunderstorms and, in some conditions, tornadoes.</span></figcaption>
</figure>
<h2>On a tornado ranking scale, how intense was this event?</h2>
<p>At least <a href="https://www.spc.noaa.gov/climo/reports/211210_rpts.html">38 tornadoes</a> have been reported in six states during this outbreak, causing <a href="https://www.nytimes.com/live/2021/12/11/us/tornadoes-midwest-south">widespread power outages, damage and fatalities</a>. The National Weather Service rates tornadoes based on the intensity of damage using 28 damage indicators from the <a href="https://www.weather.gov/oun/efscale">Enhanced Fujita, or EF, scale</a>. Storm assessments and tornado ratings can take several days or longer to complete. </p>
<p>As of Dec. 12, <a href="https://www.weather.gov/lmk/StormDamageSurveysPlannedfortheNextSeveralDays">at least</a> <a href="https://twitter.com/NWSStLouis/status/1469735019895615488?ref_src=twsrc%5Egoogle%7Ctwcamp%5Eserp%7Ctwgr%5Etweet">four</a> EF-3 and five EF-2 tornadoes have been confirmed. EF-2 and EF-3 tornadoes are considered strong, with wind speeds of 111-135 mph and 136-165 mph respectively. </p>
<p>Strong straight-line winds also occur with severe storms and can create as much damage as a tornado. After severe storms and reports of tornadoes, the National Weather Service conducts in-person storm damage surveys to determine whether a tornado or straight-line winds created the reported damage and the degree of damage. Investigators will look to see if debris is scattered in one direction, which would indicate straight-line winds, or in many different directions – the hallmark of a tornado.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/437040/original/file-20211212-144477-7ip1da.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Chart showing types of damage inflicted by winds and varying speeds on the EF scale." src="https://images.theconversation.com/files/437040/original/file-20211212-144477-7ip1da.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437040/original/file-20211212-144477-7ip1da.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437040/original/file-20211212-144477-7ip1da.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437040/original/file-20211212-144477-7ip1da.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437040/original/file-20211212-144477-7ip1da.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437040/original/file-20211212-144477-7ip1da.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437040/original/file-20211212-144477-7ip1da.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Expected damage from tornadoes at different levels of the Enhanced Fujita (EF) scale, using examples from a massive outbreak in 2011.</span>
<span class="attribution"><a class="source" href="https://www.weather.gov/hun/efscale_explanation">National Weather Service</a></span>
</figcaption>
</figure>
<h2>One tornado reportedly traveled 240 miles across four states. Why is this unusual?</h2>
<p>Most tornadoes stay on the ground for a short amount of time and <a href="https://www.nssl.noaa.gov/education/svrwx101/tornadoes/faq/#:%7E:text=How%20long%20is%20a%20tornado,average%20is%20about%20five%20minutes">travel short distances</a> – <a href="https://www.spc.noaa.gov/faq/tornado/">3-4 miles on average</a>. Long-track and very long-track tornadoes – those that travel <a href="https://www.spc.noaa.gov/publications/broyles/longtrak.pdf">at least 25 and 100 miles respectively</a> – are relatively uncommon. They account for <a href="https://doi.org/10.1016/j.parco.2015.10.014">less than 1%</a> of all tornadoes in the United States. </p>
<p>Long-track tornadoes require <a href="https://doi.org/10.1175/BAMS-D-15-00073.1">a very specific set of ingredients</a> that must exist across a wide area. These uncommon tornadoes form from a single <a href="https://www.weather.gov/ama/supercell">supercell storm</a> – a storm with a rotating updraft called a <a href="https://w1.weather.gov/glossary/index.php?word=mesocyclone">mesocyclone</a> – that can persist for hours. </p>
<p>Significant tornadoes often stay on the ground longer than weaker tornadoes. Their tracks are <a href="https://doi.org/10.1175/WAF-D-13-00057.1">especially long in the Southeast</a>, where significant tornadoes in the cool season move quickly, thus covering more ground. </p>
<p>The <a href="https://www.weather.gov/pah/1925Tornado_ss">previous record</a> for a long-track tornado was from 1925, when the F-5 Tri-State Tornado traveled 219 miles through Missouri, Illinois and Indiana. The “Quad-State Tornado,” as this tornado has been nicknamed, is <a href="https://www.wnct.com/weather/quad-state-tornado-us-may-have-just-seen-1st-ever-event-of-its-kind/">expected to break that record</a>. In the coming days, the National Weather Service will confirm whether one tornado stayed on the ground for more than 200 miles or multiple tornadoes resulted from the same storm. The agency has issued a <a href="https://www.weather.gov/pah/December-10th-11th-2021-Tornado">preliminary rating of EF-3 or greater</a> for this event.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1469671110518136837"}"></div></p>
<h2>Why do more nighttime and winter tornadoes occur in the Southeast than in other regions?</h2>
<p>Spring is typically considered tornado season, but tornadoes can occur at any time throughout the year. The Southeast experiences a <a href="https://doi.org/10.1016/j.wace.2018.03.002">second peak</a> in tornadic activity in the fall and early winter, and winter tornadoes are not uncommon. </p>
<p>Similarly, tornadoes can happen at any time of the day. Nighttime tornado events are <a href="https://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-climatology/trends">especially common</a> in the Southeast, where the <a href="https://www.semanticscholar.org/paper/Environmental-Characteristics-Associated-with-in-Mead-Thompson/d9faba87ac0fb33f308b656ba5584d1bda479116">ingredients for storms</a> are different and more conducive to nocturnal tornadoes than in “<a href="https://scied.ucar.edu/learning-zone/storms/tornadoes/where-tornadoes-happen">Tornado Alley” in the Great Plains</a>. </p>
<p>Tornadic storms in the Southeast are often powered by an abundance of wind shear. They do not rely as heavily on rising warm, humid air that creates atmospheric <a href="https://www.weather.gov/jetstream/bowls">instability</a> – conditions that require daytime heating of the earth’s surface and are more prevalent in the spring. </p>
<p>Forecasting for this event was <a href="https://www.spc.noaa.gov/products/md/md1992.html">accurate</a> and predicted a major outbreak several days in advance. The National Weather Service’s <a href="https://www.spc.noaa.gov/">Storm Prediction Center</a> in Norman, Oklahoma, and the affected National Weather Service local Weather Forecast Offices issued timely watches, warnings and information on how to stay safe. </p>
<p>But nighttime tornadoes can be <a href="https://doi.org/10.1175/2008WAF2222132.1">especially deadly</a>. More fatalities tend to occur because people often <a href="https://doi.org/10.1175/WCAS-D-17-0114.1">don’t receive warning communications</a> when they are sleeping. Storm spotting is <a href="https://doi.org/10.1175/BAMS-D-19-0245.1">more difficult in the dark</a>, and people are <a href="https://theconversation.com/tornadoes-that-strike-at-night-are-more-deadly-and-require-more-effective-warning-systems-132955">more likely to be in more vulnerable housing</a>, such as mobile homes, at night than during the day when they are at work in sturdier buildings. </p>
<p>Having <a href="https://theconversation.com/tornadoes-that-strike-at-night-are-more-deadly-and-require-more-effective-warning-systems-132955">multiple reliable methods for receiving warnings at night</a> is critical, since power can go out and cellphone service can go down during severe weather. Unfortunately, during the Dec. 10-11 event, some people who went to shelters were killed <a href="https://www.wlwt.com/article/kentucky-candle-factory-had-more-than-100-people-inside-when-tornado-hit/38492228#">when tornadoes struck the building</a> they were in. But timely warnings that allow people to shelter safely in a solid structure tied to a foundation or basement can mean survival during less-devastating events.</p>
<p><em>This article has been updated to provide the correct wind speed ranges for EF-2 and EF-3 tornadoes.</em></p>
<p>[<em>Too busy to read another daily email?</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-toobusy">Get one of The Conversation’s curated weekly newsletters</a>.]</p><img src="https://counter.theconversation.com/content/173643/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kelsey Ellis receives funding from the National Oceanic and Atmospheric Administration and the Natural Hazards Center.</span></em></p><p class="fine-print"><em><span>Alisa Hass 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>Tornadoes in December aren’t unusual in the Gulf Coast and lower Mississippi Valley states, but the Dec. 10-11 outbreak was extreme and far-reaching.Alisa Hass, Assistant Professor of Geography, Middle Tennessee State UniversityKelsey Ellis, Associate Professor of Geography, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1690852021-10-01T00:06:01Z2021-10-01T00:06:01ZTornado rips through western NSW — what are tornadoes and what do we need to know?<p>A tornado has <a href="https://www.smh.com.au/national/nsw/tornado-rips-through-central-west-severe-storm-warnings-across-nsw-20210930-p58w7o.html">swept through central western New South Wales</a>, with the Bureau of Meteorology <a href="https://media.bom.gov.au/releases/903/tornado-confirmed-in-central-western-new-south-wales/">reporting</a> damage to houses, powerlines and trees around the Clear Creek area, north-east of Bathurst.</p>
<p>But while many think of tornadoes as a rare event in Australia, <a href="https://journals.ametsoc.org/view/journals/mwre/149/5/MWR-D-20-0248.1.xml">they are actually surprisingly common</a>, and have <a href="https://www.ga.gov.au/scientific-topics/community-safety/severe-wind">killed</a> quite a number of people since European occupation. Geoscience Australia <a href="https://www.ga.gov.au/scientific-topics/community-safety/severe-wind">says</a> there have been more than 40 tornado-related deaths in Australia in the past 100 years.</p>
<p>That’s because Australia has the right environmental conditions that favour the formation of tornadoes, which have the fastest wind speeds of any natural hazard type on Earth.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/424107/original/file-20210930-14-1m3z8e2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424107/original/file-20210930-14-1m3z8e2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=440&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424107/original/file-20210930-14-1m3z8e2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=440&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424107/original/file-20210930-14-1m3z8e2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=440&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424107/original/file-20210930-14-1m3z8e2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=553&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424107/original/file-20210930-14-1m3z8e2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=553&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424107/original/file-20210930-14-1m3z8e2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=553&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The oldest known photograph of a tornado in Australia, taken at Marong in Victoria in 1911.</span>
<span class="attribution"><span class="source">C Hosken/Museum Victoria</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/tornadoes-in-australia-theyre-more-common-than-you-think-11909">Tornadoes in Australia? They're more common than you think</a>
</strong>
</em>
</p>
<hr>
<h2>Tornadoes are born, they live, they die</h2>
<p>Australia has expansive areas of flat land — usually agricultural land — and it’s over these large, flat areas that tornadoes like to form. It’s much the same in “Tornado Alley”, a stretch of central United States where tornadoes are most frequent. </p>
<p>You get thunderstorms developing over these areas of flat land because warm, moist air collides with a front of cold, dry air and that’s exactly what it takes for a storm to be born.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/WSyHhfKBUsE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How a tornado forms.</span></figcaption>
</figure>
<p>You sometimes see a tube coming out from a thundercloud and it’s only once it touches the ground that it’s a tornado. </p>
<p>How long they live on the ground and how far they travel influences the scale of damage.</p>
<p>Most storms only last a few minutes, but in Tornado Alley in the US, there have been tornadoes up to 500m in diameter on the ground for four hours. That kind of tornado would cause monumental damage.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-why-are-tornadoes-so-destructive-14519">Explainer: why are tornadoes so destructive?</a>
</strong>
</em>
</p>
<hr>
<p>Some tornadoes touch down briefly and are quite narrow, perhaps just 20m across. They might run for a few metres and then die. Others can be much bigger and obviously if they touch down in a metropolitan area they can do a lot of damage very quickly — and they can behave very unpredictably.</p>
<p>Tornadoes can go up a street and pick one house out on the street and reduce it to a pile of debris, leaving the other houses alone. Or the opposite can happen — every house on the street is smashed but one.</p>
<p>Eventually, tornadoes run out of energy. If the base of the funnel loses contact with the ground, it dies. Most tornadoes occur in the mid afternoon to early evening. </p>
<p>Much like other types of natural hazards, tornadoes can be classified according to their impact. We have a magnitude scale for tornadoes called the Enhanced Fujita scale, which goes from 0-5 (where 5 is the biggest). It’s too early to say what the recent NSW tornado measured on the Enhanced Fujita scale because damage surveys are yet to be completed.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/424103/original/file-20210930-22-17mxikl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424103/original/file-20210930-22-17mxikl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=314&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424103/original/file-20210930-22-17mxikl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=314&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424103/original/file-20210930-22-17mxikl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=314&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424103/original/file-20210930-22-17mxikl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=394&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424103/original/file-20210930-22-17mxikl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=394&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424103/original/file-20210930-22-17mxikl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=394&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tornadoes are classified in to six categories from 0 to 5, where 5 is the most destructive.</span>
<span class="attribution"><span class="source">NOAA</span></span>
</figcaption>
</figure>
<h2>Australia has had some big tornadoes</h2>
<p>The <a href="http://www.bom.gov.au/australia/stormarchive/storm.php?stormType=tornado">BOM has a national tornado database</a> and record of accounts of tornadoes over last century and some were quite big. One of the most memorable tornadoes occurred in December 2015 where a tornado ripped through the Kurnell area of eastern Sydney. No one was killed but people were injured and the tornado caused a lot of damage. Windspeeds got up to 210km per hour. According the BOM, this <a href="http://www.bom.gov.au/australia/stormarchive/storm.php?attributes%5B%5D=0&attributes%5B%5D=1&attributes%5B%5D=2&attributes%5B%5D=3&attributes%5B%5D=4&attributes%5B%5D=7&attributes%5B%5D=14&attributes%5B%5D=22&search_area=N&s_day=1&s_month=Jan&s_year=2014&e_day=30&e_month=Sep&e_year=2016&output_type=web&action=form&submit=Generate+report&stormType=tornado">tornado was recorded as a 2</a> on the Enhanced Fujita scale.</p>
<p>Generally, Australia gets tornadoes all over NSW and Victoria, as well as the southwestern part of Western Australia.</p>
<p>There is a distinct spatial geography to where tornadoes occur around the world. This map from the National Oceanic and Atmospheric Administration in the US shows those places around the world with the right conditions to allow tornadoes to form.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/424104/original/file-20210930-22-1c2duys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424104/original/file-20210930-22-1c2duys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=322&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424104/original/file-20210930-22-1c2duys.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=322&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424104/original/file-20210930-22-1c2duys.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=322&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424104/original/file-20210930-22-1c2duys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=405&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424104/original/file-20210930-22-1c2duys.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=405&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424104/original/file-20210930-22-1c2duys.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=405&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A global map of tornado regions.</span>
<span class="attribution"><span class="source">NOAA</span></span>
</figcaption>
</figure>
<h2>How do we detect, monitor and give early warning of tornadoes?</h2>
<p>The truth is it’s very hard to give precise early warnings. Rather, weather services monitor for the types of conditions right for tornado development because tornadoes can form very quickly.</p>
<p>The Bureau of Meteorology uses Doppler radar to detect them in the short term. In that imaging, they show an unusual thing called a “<a href="https://www.britannica.com/science/hook-echo">hook echo</a>”. That’s basically showing inside the thundercloud system, where winds are rotating really fast - a telltale sign that a tornado might be about to form. </p>
<p>But in Australia and in the US, we only usually know when a tornado is coming toward the ground if tornado spotters report them.</p>
<p>Can we expect them to become more frequent with climate change? We’ve got no idea. It’s impossible for climate science to predict because they are such small size phenomena. We need to rely on good planning and great spotters. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-role-of-climate-change-in-eastern-australias-wild-storms-60552">The role of climate change in eastern Australia's wild storms</a>
</strong>
</em>
</p>
<hr>
<h2>What should I do if I am in a tornado?</h2>
<p>In the US they have evacuation shelters in places such as toilets in malls or airports, which are reinforced with concrete. Residential houses tend to have a central shelter — sometimes in a cellar or under a staircase.</p>
<p>We generally don’t have that in Australia but if you end up in a tornado, it’s basically a case of “duck and cover”.</p>
<p>Find the most secure, reinforced part of the building — which is often the staircase, if the staircase is up against a wall. You want to take shelter in the part of the building that is most likely to stay up if the tornado comes over your head.</p><img src="https://counter.theconversation.com/content/169085/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dale Dominey-Howes receives funding from the Australian Research Council, the State and National Disaster Mitigation Program and the Global Resilience Partnership. </span></em></p>Australia has expansive areas of flat land — usually agricultural land — and it’s over these large, flat areas that tornadoes like to form.Dale Dominey-Howes, Professor of Hazards and Disaster Risk Sciences, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1649982021-07-29T11:55:15Z2021-07-29T11:55:15ZHurricane straps keep roofs on houses and can improve safety during tornadoes<figure><img src="https://images.theconversation.com/files/412950/original/file-20210724-21-1oss3o1.jpg?ixlib=rb-1.1.0&rect=46%2C0%2C5184%2C3437&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some of the worst damage from the EF-2 tornado that struck the Ontario city of Barrie on July 15.</span> <span class="attribution"><span class="source">(Northern Tornadoes Project)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Many people think of a well-built house as one where the walls are strong enough to hold up the roof so it won’t fall on them. This is reinforced by children’s stories like the <a href="https://americanliterature.com/childrens-stories/the-three-little-pigs">Three Little Pigs</a>, where the house made of brick is the strongest when the Big Bad Wolf comes to town. </p>
<p>When a strong tornado passes through a neighbourhood, it results in total chaos. Debris is everywhere. Shingles and siding and bricks are thrown about. Entire roofs are tossed, often landing on neighbouring homes. Walls collapse, cars are rolled and flipped. Insulation is stuck to every surface like a strange snowfall. </p>
<p>On July 15, a tornado struck Barrie, Ont., destroying several homes: Could anything have been done to minimize the damage in Barrie?</p>
<h2>Holding on to the roof</h2>
<p>In any windstorm, tornadoes included, the roof needs to be secured — this is due to the uplift, the same physics that allows an aircraft to fly. This runs counter to our intuition since we tend to think about roofs collapsing, not flying. The uplift is the main vulnerability of houses. The structure of residential roofs in Canada tend to be strong because they are designed to handle the heavy weight of snow in winter. </p>
<p>For the wind, which acts in the opposite direction as the snow, it is the nails connecting the trusses to the top of the wall that become critical to ensure that the roof stays in place during a severe storm.</p>
<p>The National Building Code of Canada requires <a href="http://www.buildingcode.online/1819.html">three nails — just over three inches long — in each roof-to-wall connection</a>. These toe nails, as they are called, are what hold the roof down in the wind. If this is done properly, <a href="https://doi.org/10.1061/AJRUA6.0000916">the roof structure should be safe until wind speeds reach about 160 kilometres an hour</a>. At such wind speeds, asphalt shingles may blow off but the roof structure will remain intact.</p>
<p>Houses are not designed for tornadoes, although the building code discusses tornadoes. The requirements for fastening the walls to the foundations were developed to deal with tornadoes. These were included in the 1995 release of the National Building Code following tragic deaths in 1984 <a href="https://doi.org/10.4224/40000493">when cottages were swept into Blue Sea Lake in Québec</a>, along with <a href="https://doi.org/10.3389/fbuil.2020.00099">post-storm observations following a 1985 tornado in Barrie</a>. </p>
<p>It is now known that toe-nailed connections are the weak links in the structure, more likely to <a href="http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.0000914">fail before the roof sheathing</a> and before the walls pull apart from the foundation. Walls are more likely to collapse when the roof is gone, and the roof itself can become airborne. Both of these are threats to life and safety.</p>
<p>The <a href="https://uwo.ca/ntp/">Northern Tornadoes Project</a> survey in the immediate aftermath of the recent tornado in Barrie indicated that several homes did not meet the building code requirements because of missing toe nails. </p>
<p>This is nothing new. </p>
<p>Similar observations were made in <a href="http://dx.doi.org/10.1139/cjce-2013-0570">2009, when tornadoes landed in Vaughan</a>, <a href="http://dx.doi.org/10.1139/cjce-2016-0232">and in 2014 in Angus</a>.</p>
<h2>Unknown speeds</h2>
<p>To design for tornadoes, we need to know the wind speeds in tornadoes. These are rarely measured. Rather, tornado wind speeds are assessed through the damage they cause, <a href="https://www.canada.ca/en/environment-climate-change/services/seasonal-weather-hazards/enhanced-fujita-scale-wind-damage.html">via the Enhanced Fujita Scale</a>. </p>
<p>The recent Barrie tornado was assessed to have had maximum wind speeds of 210 kilometres an hour based on the damage to a few of the houses. It was a strong tornado. However, if this strong tornado had instead gone through farmers’ fields, missing all buildings and trees, then it would have been assessed as an EF-0 (90-130 km/hr) tornado even though its true strength was greater. Clearly, the use of damage to estimate the tornado wind speeds is challenging, particularly in sparsely populated areas. </p>
<p>As a result, the reported intensity of a tornado — its maximum wind speed — depends on what it hits and, therefore, on the quality of construction. A roof with only a single toe nail would be <a href="https://www.canada.ca/en/environment-climate-change/services/seasonal-weather-hazards/publications/enhanced-fujita-scale-damage-indicators/chapter-2.html">assessed as EF-1, while properly installed toe nails yield an expected wind speed of about 195 kilometres an hour, which is EF-2</a>. </p>
<p>Put another way, a wood-frame roof is expected to fail in an EF-2 tornado, while improper toe nails would lead to roof failure in an EF-1 tornado. As a result of this uncertainty, quantifying wind speeds in tornadoes is still <a href="https://ams.confex.com/ams/29SLS/webprogram/Paper348726.html">an active topic of research and development</a>. </p>
<p>Nevertheless, the <a href="https://doi.org/10.1016/j.jweia.2020.104269">combination of tornado simulators</a>, wind tunnels that create tornado vortices to define the wind forces on buildings, and full-scale laboratory tests on houses to determine their strength has helped. They’ve provided good estimates of failure-inducing wind speeds during tornadoes under a range of conditions including that <a href="http://dx.doi.org/10.1139/cjce-2016-0232">of the roof-to-wall connections</a>.</p>
<p>Could anything have been done to mitigate the damage in this EF-2 tornado? In any tornado, the highest wind speeds only occur over <a href="https://doi.org/10.1175/WCAS-D-14-00032.1">a relatively small proportion of the total damage path</a>. That means damage reduction measures can be quite effective in mitigating damage from the overall storm. </p>
<p>If all of the houses in Barrie had been built to the building code requirements, there would have been less damage overall, although there still would have been some significant damage because of its intensity.</p>
<h2>Strapping down</h2>
<p>There is a better solution: the use of hurricane straps instead of toe nails. This well-established technology, developed to deal with hurricanes, can work to keep the roof attached to the walls in <a href="https://doi.org/10.3389/fbuil.2020.00099">tornadoes with wind speeds up to about EF-2</a>. They are inexpensive, costing less than $200 per house to install, and are easy to inspect for compliance. </p>
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<figcaption><span class="caption">Hurricane straps are a more efficient and safer replacement.</span></figcaption>
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<p>Since EF-2 and lower-rated tornadoes represent more <a href="https://doi.org/10.1175/BAMS-D-20-0012.1">than 95 per cent of all tornadoes</a>, requiring straps in the building code could reduce much of the damage of these severe storms and and significantly improve safety.</p>
<p>While a few other things need to be done to make houses fully able to <a href="https://www.iclr.org/wp-content/uploads/2019/04/ICLR-Western-SCC-Increasing-High-Wind-Safety-2019_EN.pdf">withstand EF-2 tornadoes</a>, this adjustment would eliminate the weakest link, increasing resilience and safety by keeping the roof on the walls and stopping entire roofs from flying downwind and hitting other buildings.</p><img src="https://counter.theconversation.com/content/164998/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gregory Kopp receives funding from NSERC, ImpactWX, Institute for Catastrophic Loss Reduction, Insurance Institute for Business and Home Safety, Structural Engineering Institute, Metal Building Manufacturers Association, Western University.</span></em></p>Current building codes do not include the most efficient way to keep houses standing and intact during tornadoes.Gregory Kopp, Professor of Civil Engineering & ImpactWX Chair of Severe Storms Engineering, Western UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1582792021-06-03T12:24:52Z2021-06-03T12:24:52ZHurricanes, wildfires, tornadoes, floods – whatever your local risk, here’s how to be more weather-ready<figure><img src="https://images.theconversation.com/files/403801/original/file-20210601-17-qeke72.jpg?ixlib=rb-1.1.0&rect=50%2C0%2C5661%2C3728&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mark Poindexter puts a tarp on the damaged roof of his home in Gulf Breeze, Louisiana, on Aug. 29, 2020, in the aftermath of Hurricane Laura.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/TropicalWeather/8c4502b0d6ec4dee9d34c9bd277de0ef/photo">AP Photo/Gerald Herbert</a></span></figcaption></figure><p>Summer in the U.S. means that it’s time to be ready for <a href="https://www.noaa.gov/media-release/noaa-predicts-another-active-atlantic-hurricane-season">hurricanes</a> and <a href="https://thedataface.com/2018/11/public-health/wildfires-map">wildfires</a>. The incidence of weather and climate disasters is <a href="https://www.climate.gov/news-features/blogs/beyond-data/2020-us-billion-dollar-weather-and-climate-disasters-historical">increasing in the U.S.</a>, a trend due partly to <a href="https://theconversation.com/western-fires-are-burning-higher-in-the-mountains-at-unprecedented-rates-in-a-clear-sign-of-climate-change-159699">climate change</a> but also to human decisions. </p>
<p>Since the 1950s, population growth has <a href="https://www.nber.org/system/files/working_papers/w13071/w13071.pdf">increased significantly in Sun Belt states</a>. Millions of people have moved to coastlines, from Texas to the Carolinas, putting more lives and property in harm’s way during hurricanes. Florida, the hurricane capital of the United States, now is the <a href="https://worldpopulationreview.com/en/states">third-most-populous state in the nation</a>.</p>
<p>Recognizing that Americans are increasingly vulnerable to extreme weather, the National Oceanic and Atmospheric Administration’s <a href="https://www.weather.gov/wrn/">Weather-Ready Nation initiative</a> is helping communities plan for events like violent tornadoes, destructive hurricanes and widespread flooding. As a <a href="https://www.weather.gov/people/salna-erik">meteorologist and supporter of this effort</a>, I believe that everyone should understand what kinds of severe weather hazards could affect their family and home and be ready for them. Here are some ways to do it.</p>
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<h2>What to do instead of taping windows</h2>
<p>For Atlantic and Gulf coast residents, hurricane preparedness has to be a way of life. It means knowing whether you live in a <a href="https://flash.org/pdf/2020_Hurricane_Evacuation_Zones.pdf">designated evacuation zone</a>. That’s key in the event of storm surge – when a hurricane pushes seawater up onto local beaches and inland areas. Readiness also means having a family and business disaster plan that details preparations, and maintaining a <a href="https://dem.fiu.edu/emergencies/emergency-kit/index.html">hurricane survival kit</a>. </p>
<p>Another priority is knowing how to protect your home and business from damaging winds. Conducting a home insurance review with your agent and scheduling a <a href="https://www.homeinspector.org/">wind mitigation inspection</a> will identify what you can do to strengthen and protect vulnerable parts of the building such as windows, entry doors, garage doors and roofs. </p>
<p>Adding metal hurricane shutters or hurricane-resistant windows can help. So can retrofitting the attic or eaves with <a href="https://apps.floridadisaster.org/hrg/content/walls/wood_frame_rtw_conn.asp">metal hurricane straps</a>, which connect the rafters to the walls to prevent the roof from blowing off.</p>
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<figcaption><span class="caption">The owner of a Mexico Beach, Florida, house that survived Hurricane Michael, a Category 5 storm in 2018, describes his home’s stormproofing features.</span></figcaption>
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<p>Here’s one step to skip: Putting tape onto windows for wind protection from a hurricane. Tape does nothing to reduce wind damage, so this is a waste of time. </p>
<p>Consumers also need to rethink how they shop for a new home in storm-prone areas. It’s OK to want granite countertops, walk-in closets and a safe neighborhood near schools and parks. But buyers should also consider how well a house is built, its age, the materials it contains, the shape and condition of the roof, and building code requirements at the time it was constructed. </p>
<p>And they should ask whether the house is located in a <a href="https://www.fema.gov/flood-maps">flood-prone area</a>, has wind-resistant features or has been <a href="https://apps.floridadisaster.org/hrg/">retrofitted against hurricanes</a>. Even residents who don’t live in a zone where it is required should consider taking out flood insurance.</p>
<h2>Storm-testing buildings</h2>
<p>Florida International University’s <a href="https://www.ihrc.fiu.edu/">International Hurricane Research Center</a>, which is part of our <a href="https://eei.fiu.edu/">Extreme Events Institute</a>, was designated NOAA’s first Weather-Ready Nation ambassador in South Florida. Our <a href="https://fiu.designsafe-ci.org/">Wall of Wind</a> facility is capable of creating Category 5 hurricane conditions – winds with speeds over 157 mph. </p>
<p>Like crash testing for vehicles, wind testing can help ensure that structures, traffic signals and building components can hold up under stress. The Wall of Wind is part of the National Science Foundation’s <a href="https://www.designsafe-ci.org/about/">Natural Hazards Engineering Research Infrastructure program</a>. </p>
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<figcaption><span class="caption">A Wall of Wind demonstration shows how inexpensive building reinforcements can prevent costly hurricane damage.</span></figcaption>
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<p>For educational outreach, we host the yearly <a href="https://news.fiu.edu/2021/virtual-wall-of-wind-challenge-inspires-high-school-students-to-tackle-real-world-problems?utm_source=Newsletter&utm_medium=Email&utm_campaign=FIU%20Newsletter">Wall of Wind Mitigation Challenge</a>, in which teams of local high school students develop innovative wind mitigation concepts and solutions. And the Extreme Events Institute uses a <a href="https://eei.fiu.edu/equation/the-equation/">risk equation</a> to help the public understand and support measures to confront the “risk drivers” that lead to major losses.</p>
<p>For more about hurricane mitigation and preparedness, watch our 12-episode “<a href="https://mods.org/eyeofthestorm/">Eye of the Storm</a>” video series, or visit our <a href="https://huracanes.fiu.edu/">Spanish-language hurricane website</a>.</p>
<h2>Wildfires, tornadoes and floods</h2>
<p>NOAA’s <a href="https://www.weather.gov/">National Weather Service</a> is also investing in new forecasting tools and <a href="https://www.weather.gov/news/192203-strategic-plan">linking its forecasts to lifesaving decisions</a> made in every state and county. The goal is to provide timely forecasts that emergency managers, first responders, government officials, businesses and the public can act on.</p>
<p>Across the United States, Weather-Ready Nation ambassadors are preparing for many types of extreme weather events. </p>
<p>Another <a href="https://theconversation.com/another-dangerous-fire-season-is-looming-in-the-western-u-s-and-the-drought-stricken-region-is-headed-for-a-water-crisis-160848">extreme wildfire season</a> is expected in many Western states. The Oregon Office of Emergency Management is asking residents to <a href="https://phys.org/news/2021-05-good-summer-wildfire-season.html">have a bag packed and to prepare an evacuation plan</a>. </p>
<p>Flooding can occur almost anywhere across the country, and hazards can develop quickly. Flooded roadways can be deadly, so take heed of NOAA’s “Turn Around Don’t Drown” message and <a href="https://www.weather.gov/safety/flood-turn-around-dont-drown">avoid walking or driving in flooded areas</a> – it could save your life. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/COLBDZEDGKN/?utm_source=ig_web_copy_link","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>Tornado safety is critical. Tornado readiness includes <a href="https://www.weather.gov/oun/safety-severe-homesafety">knowing the safest room in your home</a> – usually a windowless interior room on the lowest floor – and <a href="https://www.weather.gov/nwr/">tuning in to NOAA Weather Radio</a>, which will provide severe-weather information directly from your local National Weather Service office. </p>
<p>During any severe weather event, such as the <a href="https://theconversation.com/the-texas-blackouts-showed-how-climate-extremes-threaten-energy-systems-across-the-us-155834">February 2021 deep freeze in Texas</a>, the power may go out, so everyone should have flashlights and batteries on hand. Portable generators can be useful during extended outages, but <a href="https://www.cdc.gov/co/pdfs/generators.pdf">always operate them outdoors</a> to avoid the risk of <a href="https://www.texastribune.org/2021/04/29/texas-carbon-monoxide-poisoning/">carbon monoxide poisoning</a>.</p>
<p>Apathy and complacency can also be dangerous when it comes to weather-driven disasters. In my view, weather readiness has to become a way of life – something that all Americans see as their responsibility. The best forecasts in the world may be useless if the public doesn’t respond or hasn’t taken the needed actions to protect themselves when extreme weather threatens.</p>
<p>Most importantly, remember to help your neighbors when needed, especially if they are elderly and can’t help themselves. In addition, consider supporting local nonprofits or churches that help residents in your community who have financial or transportation needs to be ready and safe. We are all in this together.</p><img src="https://counter.theconversation.com/content/158279/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Erik Salna currently leads education and outreach projects funded by the Florida Division of Emergency Management and the Inter-American Teacher Education Network (ITEN) with the Organization of American States (OAS).
</span></em></p>Federal weather scientists are pushing to make the US more ‘weather-ready,’ which could mean prepping for fires, flooding or storms depending on where you live. The common factor: thinking ahead.Erik Salna, Associate Director of Education and Outreach, Extreme Events Institute, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1599972021-05-06T05:05:22Z2021-05-06T05:05:22ZWhat are waterspouts, and how do they form? An expert explains<figure><img src="https://images.theconversation.com/files/399128/original/file-20210506-15-1anfj2i.jpg?ixlib=rb-1.1.0&rect=2%2C2%2C1625%2C1195&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Trombe.jpg">Joseph Golden / NOAA</a></span></figcaption></figure><p>Waterspouts are extraordinary, impressive weather events. Observers <a href="https://www.news.com.au/travel/travel-updates/health-safety/the-start-of-an-alien-invasion-freak-water-spouts-form-off-nsw-coast/news-story/3b4ec00ba6350ff6d2170f53b94f1cf9">describe</a> them as looking like “the start of an alien invasion” and post their snaps across social media.</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/COcSU-1FmYg","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<p>But what are these enigmatic offshore twisters, and what causes them to form?</p>
<h2>What is a waterspout?</h2>
<p>A waterspout is a <a href="http://www.bom.gov.au/nsw/sevwx/handbook/spotter6.shtml">spinning column of air</a> that sucks up water (usually from the ocean) to make a twisting funnel of water and cloud connecting the sea and the sky.</p>
<p>They are spectacular but short lived, usually lasting no more than five minutes (but occasionally up to ten minutes). Winds inside the waterspout can be faster than 100 kilometres per hour, and they can do great damage to boats at sea. </p>
<p>If they drift ashore, waterspouts can create even more havoc: the <a href="https://www.news.com.au/breaking-news/school-closed-as-northern-nsw-floods/news-story/e060f30d2a4af481832e5a4a7bc40207">Lennox Head tornado</a> in 2010 destroyed a dozen homes in northern NSW.</p>
<p>Waterspouts are in some ways like the tornadoes that form over land. But where tornadoes are associated with huge supercell thunderstorms, waterspouts can form during smaller storms or even just showers or the presence of the right kind of clouds.</p>
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Read more:
<a href="https://theconversation.com/tornadoes-in-australia-theyre-more-common-than-you-think-11909">Tornadoes in Australia? They're more common than you think</a>
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<h2>How do waterspouts form?</h2>
<p>Waterspouts can form when winds blowing in two different directions run into each other. Along the line where the two winds meet (called a “convergence line” or “shear line”), there is a lot of rotating air near the surface. </p>
<p>The collision of the two winds makes air move upwards because it has nowhere else to go. This rising air carries water vapour high into the sky where it creates rain showers, storms and <a href="http://www.bom.gov.au/weather-services/about/cloud/cloud-types.shtml">cumulus clouds</a>.</p>
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<img alt="" src="https://images.theconversation.com/files/399131/original/file-20210506-14-1dbe1qk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/399131/original/file-20210506-14-1dbe1qk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/399131/original/file-20210506-14-1dbe1qk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/399131/original/file-20210506-14-1dbe1qk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/399131/original/file-20210506-14-1dbe1qk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/399131/original/file-20210506-14-1dbe1qk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/399131/original/file-20210506-14-1dbe1qk.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">
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<span class="caption">Waterspouts off the coast at Harrington in NSW.</span>
<span class="attribution"><span class="source">Sue McDonald</span>, <span class="license">Author provided</span></span>
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<p>As the air rises, it can tilt some of the horizontal spinning air near the surface into the vertical direction. When this vertical spin concentrates at a particular point it starts sucking up water — and you have yourself a waterspout.</p>
<p>Because waterspouts form on the line where two winds meet, you sometimes see a line of waterspouts in a row where the spinning low-level air is sucked upwards at a few different points. </p>
<h2>When and where are waterspouts most common?</h2>
<p>In Australia, waterspouts are most common along the NSW and Queensland coast. </p>
<p>Most mornings, cooler nighttime air blowing off the land meets warmer air sitting out to sea. Usually this results in a line of clouds sitting offshore where the two air masses meet.</p>
<p>Under the right conditions — most often in autumn and winter, when the land gets colder but the sea stays relatively warm — the collision becomes more dramatic and waterspouts appear.</p>
<h2>Can we forecast waterspouts?</h2>
<p>Waterspouts look very big and impressive to the casual viewer, but to a meteorologist looking at the world’s weather patterns they are quite small. This makes them very hard to forecast with any level of confidence.</p>
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Read more:
<a href="https://theconversation.com/curious-kids-how-do-people-know-what-the-weather-will-be-108295">Curious Kids: how do people know what the weather will be?</a>
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<p>We know the kind of weather conditions that can lead to waterspouts, so if we see those conditions forming we might know there is a chance we’ll see some. But the small scale and short life of waterspouts mean forecasting the location or timing is almost impossible.</p><img src="https://counter.theconversation.com/content/159997/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dean Narramore 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>While land tornadoes are associated with huge supercell thunderstorms, waterspouts can form during smaller storms or even just showers or the presence of the right kind of clouds.Dean Narramore, Senior meteorologist, Australian Bureau of MeteorologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1561732021-03-18T17:15:59Z2021-03-18T17:15:59ZHurricane warnings and advice can get lost in translation, leaving migrants unprepared<figure><img src="https://images.theconversation.com/files/390184/original/file-20210317-13-1d7mx31.jpg?ixlib=rb-1.1.0&rect=26%2C0%2C3000%2C1976&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Migrant workers in a Florida community hit hard by Hurricane Irma line up for donated supplies.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/residents-of-the-rural-migrant-worker-town-of-immokalee-news-photo/846617080">Spencer Platt/Getty Images</a></span></figcaption></figure><p>Forecasters expect <a href="https://theconversation.com/atlantic-hurricane-season-starts-june-1-heres-what-forecasters-are-watching-right-now-161065">another active Atlantic hurricane season</a> after a <a href="https://www.noaa.gov/media-release/record-breaking-atlantic-hurricane-season-draws-to-end">record-breaker in 2020</a>, and communities need to be prepared. <a href="https://www.researchgate.net/publication/342439097_Translation_in_Times_of_Cascading_Crisis_Call_for_Abstracts">Clear communications</a>, starting before storms arrive and continuing through the recovery, will be crucial to protecting lives and limiting property damage.</p>
<p>Unfortunately, parts of the population are slipping through the cracks when it comes to hurricane warnings and advice.</p>
<p><a href="http://www.id-coop.eu/en/KeyConcepts/Pages/LinguisticMinorities.aspx#:%7E:text=A%20linguistic%20minority%20is%20a,spoken%20by%20the%20national%20majority.">Linguistic minorities</a> – those who understand little or no English – are often at greater risk from disasters and have fewer resources to evacuate or protect their homes. When <a href="https://www.history.com/topics/natural-disasters-and-environment/hurricane-katrina">Hurricane Katrina</a> hit New Orleans in 2005, many migrants didn’t evacuate, in part because <a href="https://doi.org/10.1016/j.geoforum.2020.07.007">storm warnings were broadcast mainly in English</a>. It’s a simmering public health issue, with clear implications for migrant communities.</p>
<p>As part of a <a href="https://doi.org/10.1016/j.ijdrr.2021.102061">new study</a>, we looked at local emergency communication in English and compared it to nine other languages. Our results show how minor deviations in translation could lead to significant differences in understanding. Those gaps could cause linguistic minorities to confuse one natural hazard with another, misunderstand advice and quite possibly lead to the wrong preventive measures.</p>
<h2>When direct translation doesn’t work</h2>
<p>What forecasters call a “hurricane” in the U.S. might be called <a href="http://media.bom.gov.au/social/blog/6/tornado-twister-hurricane-tropical-cyclone-typhoonwhats-the-difference/">a “cyclone” or “typhoon” in other countries</a>. But they are all the same natural phenomenon.</p>
<p>The word “typhoon” has an Arabic origin, “<a href="https://www.lexilogos.com/english/arabic_dictionary.htm">tawaphan</a>,” but the word in Arabic means “flooding.” The word also can be found in Persian as “<a href="http://www.farsidic.com/en/Lang/EnFa">tophan</a>,” where it means a “rainstorm.” The word exists in Hindi as well, “<a href="https://www.lexilogos.com/english/hindi_dictionary.htm">toophan</a>,” and simply means a “storm.”</p>
<p>The two words “tornado” and “hurricane” are translated into the same word in Arabic, “<a href="https://www.lexilogos.com/english/arabic_dictionary.htm">iiesar</a>.” But this word describes only a circular movement of wind. The term used in Arabic to describe a hurricane is “<a href="https://www.lexilogos.com/english/arabic_dictionary.htm">iiesar bahri</a>,” which is translated back to English as “sea cyclone.”</p>
<p>In the U.S., the words “<a href="http://media.bom.gov.au/social/blog/6/tornado-twister-hurricane-tropical-cyclone-typhoonwhats-the-difference/">tornado” and “twister” are used interchangeably</a> in English, but in Spanish, they are not. In Spanish, “tornado” is translated to “tornado,” while “twister” is translated to “<a href="https://www.spanishdict.com/dictionary">torbellino</a>” or “<a href="https://www.spanishdict.com/dictionary">tromba</a>,” which is translated back to English as “whirlwind.” Similarly, “tornado” is translated to “<a href="http://www.farsidic.com/en/Lang/EnFa">kardbad</a>” in Persian, which also means a “whirlwind.” In both cases, the translations fail to reflect the severity of the event; it makes the hazard sound less dangerous.</p>
<p>Misunderstanding can go in the other direction as well, leading to unnecessary panic. The word “hurricane” assumes a certain cultural context around the world. This is mainly due to <a href="https://www.warc.com/rankings/media-100/top-countries/2020">media coverage</a> of actions taken by the U.S. government during hurricanes. Because of this, migrants from India might assume that hurricanes are more destructive than cyclones if they compare the <a href="https://abcnews.go.com/US/federal-government-poised-respond-hurricane-florence/story?id=57806869">U.S. government response to hurricanes</a> to the <a href="https://www.aljazeera.com/news/2020/5/20/many-killed-as-cyclone-amphan-tears-into-india-bangladesh-coasts">Indian government response to cyclones</a>.</p>
<p>The knock-on effect is that human behavior in response to the same natural phenomena is altered. This can spread panic among migrants, <a href="https://www.psychologytoday.com/us/blog/media-spotlight/201610/why-do-we-panic-in-emergencies">which can be as hazardous as not being prepared during emergencies</a>.</p>
<p>The problems do not end with “hurricane” and “tornado.” We found similar issues arising with terms used to describe seismic events, monsoonal dust and sand storms. And we are only scratching the surface. Our data are limited to 10 languages out of more than <a href="https://www.ethnologue.com/guides/how-many-languages">7,100 spoken languages around the world</a>.</p>
<figure class="align-center ">
<img alt="Word art with storm terms in the shape of Earth" src="https://images.theconversation.com/files/387978/original/file-20210305-19-1pobpk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/387978/original/file-20210305-19-1pobpk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/387978/original/file-20210305-19-1pobpk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/387978/original/file-20210305-19-1pobpk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/387978/original/file-20210305-19-1pobpk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/387978/original/file-20210305-19-1pobpk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/387978/original/file-20210305-19-1pobpk.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">Around the world, people use different words for similar – but not always identical – weather phenomena.</span>
<span class="attribution"><span class="source">Created with wordart.com</span></span>
</figcaption>
</figure>
<h2>Creating more inclusive emergency messaging</h2>
<p>Our data demonstrate the importance of careful attention to language choices in emergency communications. The gaps that we have observed can cause linguistic minorities to confuse one natural hazard with another, quite possibly leading to the <a href="https://www.nbcnews.com/mach/science/what-s-difference-between-hurricane-tornado-ncna1011676">wrong preventive measures.</a></p>
<p>Writing and translating emergency communications <a href="https://www.e-ir.info/2021/01/18/how-the-english-language-dominates-disaster-research-and-practice/">with cultural sensitivity</a> can avoid some of these disadvantages and the potential for unintentional harm.</p>
<p>Beyond overcoming translation barriers, there are opportunities to promote inclusive disaster preparedness that doesn’t leave anyone behind. Emergency communication should be tailored to the needs of local communities. This can happen only when a strategy for action is created collaboratively <a href="https://www.bangthetable.com/blog/healing-together-emergency-management-and-disaster-recovery/">with the community</a> and is actually followed. </p>
<p>In the U.S., <a href="https://cis.org/Report/Almost-Half-Speak-Foreign-Language-Americas-Largest-Cities">67 million people speak a foreign language in their homes</a>. Communicating in different languages and understanding the original cultural context might sound like a lot of work, but local communities can and do help <a href="https://www.elrha.org/project-blog/value-communicating-local-language/">support such initiatives</a>. </p>
<p>The institutions that people rely on for emergency communication are increasingly paying attention to diversity and inclusion. Linguistic inclusion can make an important contribution to their broader public health efforts. </p>
<p><em>This article was update with the start of hurricane season.</em></p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/156173/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 organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Misunderstanding disaster warnings can have catastrophic consequences for people who don’t speak the language used for emergency communications.Amer Hamad Issa Abukhalaf, Research Assistant and Ph.D. Candidate, University of FloridaJason von Meding, Associate Professor, Florida Institute for Built Environment Resilience, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1572752021-03-17T12:14:10Z2021-03-17T12:14:10ZWild weather: 4 essential reads about tornadoes and thunderstorms<figure><img src="https://images.theconversation.com/files/389943/original/file-20210316-15-1p8xg81.jpg?ixlib=rb-1.1.0&rect=49%2C0%2C5472%2C3637&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Debris near Lebanon, Tennessee, after tornadoes struck on the night of March 3, 2020, killing more than 20 people across the state. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/NashvilleTragedies-OneYearLater/beedd1a8612543bc8dcb6d35ee39ec2e/photo">AP Photo/Mark Humphrey</a></span></figcaption></figure><p>Springtime in the U.S. is frequently a season for thunderstorms, which can spawn tornadoes. These large storms are common in the South and Southeast in March and April, then shift toward the Plains states in May. Scientists have warned that 2021 could be an <a href="https://www.washingtonpost.com/weather/2021/02/25/active-tornado-season-south/">active tornado year</a>, partly because of a La Niña climate pattern in the tropical Pacific Ocean. Past research has suggested that La Niña increases the frequency of tornadoes and hail by concentrating hot, humid air over Texas and other Southern states, which <a href="https://www.climate.gov/news-features/featured-images/el-ni%C3%B1o-and-la-ni%C3%B1a-affect-spring-tornadoes-and-hailstorms">helps to promote storm formation</a>. </p>
<p>These four articles from The Conversation’s archives explain how tornadoes form, why night tornadoes are more deadly, and how in rare cases thunderstorms can take a different but equally destructive form – a derecho. We also look at a neglected aspect of disaster response: disposing of massive quantities of waste. </p>
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<h2>1. How thunderstorms generate tornadoes</h2>
<p>Most tornadoes are spawned by large, intense thunderstorms called supercell thunderstorms. The key ingredients are rising air that rotates, and wind shear – winds at different altitudes blowing at different speeds, and/or from different directions. </p>
<p>Forecasters can’t always predict when or where a tornado may form, but they are very good at identifying the conditions that have the potential to support strong tornadoes. As Penn State university meteorologists <a href="https://scholar.google.com/citations?user=T2Ozg5EAAAAJ&hl=en">Paul Markowski</a> and <a href="https://scholar.google.com/citations?user=EUp5dOkAAAAJ&hl=en">Yvette Richardson</a> explain, </p>
<blockquote>
<p>“The National Weather Service’s Storm Prediction Center routinely predicts large outbreaks days in advance. ‘High-risk’ outlooks capture most <a href="https://theconversation.com/understanding-tornadoes-5-questions-answered-77448">major tornado events</a>, and strong tornadoes rarely occur outside of tornado watches. We have less ability to forecast tornadoes in more marginal situations, such as within non-supercell storms.”</p>
</blockquote>
<h2>2. A special risk in the South: Night tornadoes</h2>
<p>Tornado strikes are bad news at any time, but especially when they occur at night. Night tornadoes are more than twice as likely to be fatal as daytime twisters, for several reasons: They are harder for storm spotters to see, people may sleep through alerts, and victims are more likely to be in vulnerable structures such as mobile homes at night. </p>
<p>Night tornadoes are more common in the South because of regional atmospheric conditions there. University of Tennessee geographer <a href="https://scholar.google.com/citations?user=LvpAEa0AAAAJ&hl=en">Kelsey Ellis</a> and Middle Tennessee State University geoscientist <a href="https://scholar.google.com/citations?user=BZn_vToAAAAJ&hl=en">Alisa Hass</a> write that communication challenges are a serious problem in their state, where <a href="https://theconversation.com/tornadoes-that-strike-at-night-are-more-deadly-and-require-more-effective-warning-systems-132955">nearly half of tornadoes strike at night</a>. </p>
<p>“Experts in Tennessee recommend having multiple methods for receiving warnings at night,” they note. “This strategy allows for backup options when power goes out, cellphones go down or other unforeseen circumstances occur.”</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/LT7yRMLAkCY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">What causes some supercell thunderstorms to become tornadoes?</span></figcaption>
</figure>
<h2>3. Derechos: Storms without spin</h2>
<p>In rare instances, weather systems can generate organized lines of thunderstorms called derechos, from the Spanish word for “straight ahead.” For a storm to qualify as a derecho, it has to produce winds of 57.5 mph (26 meters per second) or greater. And those intense winds must extend over a path at least 250 miles (400 kilometers) long, with no more than three hours separating individual severe wind reports.</p>
<p>Most areas of the Central and eastern U.S. may experience a derecho once or twice a year on average. They occur mainly from April through August, but they can also occur earlier in spring or later in fall. And they can inflict heavy damage. A derecho that swept across the Midwest in August 2020 generated <a href="https://www.desmoinesregister.com/story/news/2020/10/17/iowas-august-derecho-most-costly-thunderstorm-us-history-7-5-billion-damages/3695053001/">over US$7.5 billion in damages</a> – the nation’s most costly thunderstorm. </p>
<p>Derechos can be even harder to predict than tornadoes, and once they form, they can move very fast. As Colorado State University atmospheric scientist <a href="https://scholar.google.com/citations?user=vfbhQHkAAAAJ&hl=en">Russ Schumacher</a> warns, </p>
<blockquote>
<p>“Communities, first responders and utilities may have only a few hours to prepare for an oncoming derecho, so it is important to know how to receive severe thunderstorm warnings, such as TV, radio and smartphone alerts, and to take these warnings seriously. Tornadoes and tornado warnings often get the most attention, but lines of severe thunderstorms <a href="https://theconversation.com/what-is-a-derecho-an-atmospheric-scientist-explains-these-rare-but-dangerous-storm-systems-140319">can also pack a major punch</a>.”</p>
</blockquote>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/389947/original/file-20210316-13-1if6rhj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Metal silo twisted and folded by winds." src="https://images.theconversation.com/files/389947/original/file-20210316-13-1if6rhj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389947/original/file-20210316-13-1if6rhj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389947/original/file-20210316-13-1if6rhj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389947/original/file-20210316-13-1if6rhj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389947/original/file-20210316-13-1if6rhj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389947/original/file-20210316-13-1if6rhj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389947/original/file-20210316-13-1if6rhj.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 August 2020 derecho crumpled this grain storage tower in Martelle, Iowa.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2jxjHas">Phil Roeder/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>4. Cleaning up after storms</h2>
<p>Tornadoes and other natural disasters often leave huge quantities of debris behind – uprooted trees, splintered buildings, smashed cars and more. It can take communities months or even years to clean up, and the process typically is slow, expensive and dangerous. </p>
<p><a href="https://scholar.google.com/citations?user=vUhXX-MAAAAJ&hl=en">Sybil Derrible</a> of the University of Illinois–Chicago, <a href="https://scholar.google.com/citations?user=rytzGosAAAAJ&hl=en">Juyeong Choi</a> of Florida State University and <a href="https://scholar.google.com/citations?user=J8dGrPwAAAAJ&hl=en">Nazli Yesiller</a> of California Polytechnic State University study urban engineering, disaster management and planning, and waste management. They see a need for new technologies and strategies that officials can use to figure out what materials storm debris contains and find options for <a href="https://theconversation.com/millions-of-burnt-trees-and-rusted-cars-post-disaster-cleanup-is-expensive-time-consuming-and-wasteful-123566">separating, reusing and recycling it</a>. </p>
<blockquote>
<p>“For example, drones and autonomous sensing technologies can be combined with artificial intelligence to estimate amounts and quality of debris, the types of materials it contains and how it can be repurposed rapidly. Technologies that allow for fast sorting and separation of mixed materials can also speed up debris management operations,” they write.</p>
<p>“Turning the problem around, creating new sustainable construction materials – especially in disaster-prone areas – will make it easier to repurpose debris after disasters.”</p>
</blockquote>
<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p>
<p>[<em>Get the best of The Conversation, every weekend.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklybest">Sign up for our weekly newsletter</a>.]</p><img src="https://counter.theconversation.com/content/157275/count.gif" alt="The Conversation" width="1" height="1" />
With the onset of spring come thunderstorms, and sometimes tornadoes. Learn how these systems form and why night tornadoes are especially deadly.Jennifer Weeks, Senior Environment + Cities Editor, The ConversationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1449042020-08-25T12:23:19Z2020-08-25T12:23:19ZExtreme wildfires can create their own dangerous weather, including fire tornadoes – here’s how<figure><img src="https://images.theconversation.com/files/354215/original/file-20200822-20-19xko0w.jpg?ixlib=rb-1.1.0&rect=4%2C17%2C2968%2C1926&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Extreme wildfires can fuel tornadoes, creating erratic and dangerous conditions for firefighters.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/firefighting-helicopter-makes-a-water-drop-next-to-a-small-news-photo/167983094">David McNew/Getty Images</a></span></figcaption></figure><p>It might sound like a bad movie, but extreme wildfires can create their own weather – including fire tornadoes.</p>
<p>It happened in California as a heat wave helped to fuel hundreds of wildfires across the region, many of them sparked by lightning. One fiery funnel cloud on Aug. 15 was so powerful, the National Weather Service issued what’s believed to be its first <a href="http://mesonet.agron.iastate.edu/wx/afos/p.php?pil=TORREV&e=202008152135">fire tornado warning</a>.</p>
<p>So, what has to happen for a wildfire to get so extreme that it spins off tornadoes?</p>
<p>As <a href="https://scholar.google.com/citations?user=HCfUlVIAAAAJ&hl=en">professors who study</a> <a href="https://scholar.google.com/citations?user=PHyhP_AAAAAJ&hl=en">wildfires and weather</a>, we can offer some insights.</p>
<h2>How extreme fire conditions form</h2>
<p>Fires have three basic elements: heat, fuel and oxygen. </p>
<p>In a wildland fire, a heat source ignites the fire. Sometimes that ignition source is a car or power line or, as the West saw in mid-August, lightning strikes. Oxygen then reacts with dry vegetation to <a href="https://www.nps.gov/articles/wildland-fire-behavior.htm#:%7E:text=The%20Fire%20Behavior%20Triangle,and%20their%20influence%20on%20fire">produce heat, ash and gases</a>. How dry the landscape is determines whether the fire starts, how fast it burns and how hot the fire can get. It’s almost as important as wind.</p>
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<p>Fire weather conditions get extreme when high temperatures, low humidity and strong winds combine with dead and live vegetation to produce difficult-to-fight, fast-spreading wildfires.</p>
<p>That combination is exactly what the West has been seeing. A wet winter fed the growth of grasses that now cover large areas of wildland in the western U.S. Most of this grass is now dead from the summer heat. Combined with other types of vegetation, that leaves lots of <a href="https://www.mdpi.com/2571-6255/3/3/29">fuel for the wildfires</a> to burn. </p>
<p>The remnants of <a href="https://www.nhc.noaa.gov/archive/2020/ELIDA.shtml">Hurricane Elida</a> also played a role. The storm increased moisture and instability in the atmosphere, which triggered thunderstorms further north. The atmosphere over land was pretty dry by then, and even when rain formed at the base of these clouds, it mostly evaporated due to the excessive heat. This led to “dry lightning” that ignited wildfires.</p>
<h2>Wildfires can fuel thunderstorms</h2>
<p><a href="https://doi.org/10.1175/MWR-D-17-0253.1">Fires can also cause convection</a> – hot air rises, and it moves water vapor, gases and aerosols upward. </p>
<p>Wildfires with turbulent plumes can produce a “cumulus” type of cloud, known as pyrocumulus or pyrocumulonimbus. Pyrocumulus clouds are <a href="https://eo.ucar.edu/webweather/cumulus.html">similar to the cumulus clouds</a> people are used to seeing. They develop when hot air carries moisture from plants, soil and air upward, where it cools and condenses. The centers of these “pyroclouds” have strong rising air. </p>
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<p>It’s pretty common, and it’s a warning sign that firefighters could be facing erratic and dangerous conditions on the ground from the indraft of air toward the center of the blaze.</p>
<p>In some cases, the pyroclouds can reach 30,000 feet and produce lightning. There is evidence that pyrocumulus lightning may have ignited new blazes during the devastating fire storm in Australia in 2009 known as “<a href="https://doi.org/10.5194/nhess-20-1497-2020">Black Friday</a>.”</p>
<h2>Where do fire tornadoes come from?</h2>
<p>Similar to the way <a href="https://www.metoffice.gov.uk/weather/learn-about/weather/types-of-weather/clouds/low-level-clouds/cumulonimbus">cumulonimbus clouds</a> produce tornadoes, these pyroclouds can produce fire‐generated vortices of ash, smoke and often flames that can get destructive. </p>
<p>A vortex can form because of the intense heat of the fire in an environment with strong winds. This is similar to a strong river flow passing through a depression. The sudden change in the speed of the flow will force the flow to rotate. Similarly, the heat generated by the fire creates a low pressure, and in an environment with strong winds, this process results in the formation of a vortex.</p>
<p><a href="https://doi.org/10.1029/2018GL080667">One fire tornado</a>, or fire whirl, that developed during the deadly 2018 Carr Fire devastated parts of Redding, California, with winds clocked at over 143 miles per hour.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/7ptCSs6uyu4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>These vortices can also increase the severity of the fires themselves by sucking air rich in oxygen toward the center of the vortex. The hotter the fire, the higher the probability of stronger updrafts and stronger and larger vortices.</p>
<p>Persistent heat waves that dry out the land and vegetation have increased the potential of wildfires to be more violent and widespread.</p>
<h2>Is extreme fire weather becoming more common?</h2>
<p>Global warming has modified the Earth’s climate in ways that profoundly affect the behavior of wildfires.</p>
<p>Scientific <a href="https://www.climateassessment.ca.gov/">evidence suggests</a> that the severity of prolonged droughts and heat waves has been exacerbated not only by rising temperatures but also by changes in atmospheric circulation patterns associated with recent climate change. These changes can enhance extreme fire-weather behavior.</p>
<p>A study published Aug. 20 found that the frequency of California’s extreme fire weather days in the autumn fire season had <a href="https://doi.org/10.1088/1748-9326/ab83a7">more than doubled</a> since the early 1980s. Over that four-decade period, autumn temperatures in the state rose by about 1.8 degrees Fahrenheit and autumn precipitation decreased by about 30%.</p>
<p>Firefighters and people living in wildfire-prone areas, meanwhile, need to be prepared for more extreme wildfires in the coming years.</p><img src="https://counter.theconversation.com/content/144904/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Charles Jones receives funding from the National Science Foundation and the University of California. </span></em></p><p class="fine-print"><em><span>Leila Carvalho receives funding from the National Science Foundation.</span></em></p>Persistent heat waves and dry lightning are part of the problem. For firefighters, the erratic behavior gets dangerous quickly.Charles Jones, Professor of Atmospheric Science, University of California, Santa BarbaraLeila Carvalho, Professor of Meteorology and Climatology, University of California, Santa BarbaraLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1403192020-06-15T12:19:55Z2020-06-15T12:19:55ZWhat is a derecho? An atmospheric scientist explains these rare but dangerous storm systems<figure><img src="https://images.theconversation.com/files/341358/original/file-20200611-80784-qr10wr.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5122%2C3379&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A derecho moves across central Kansas on July 3, 2005.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/deadly-derecho-strikes-central-kansas-news-photo/595068428?adppopup=true">Jim Reed/Corbis via Getty Images</a></span></figcaption></figure><p>Thunderstorms are common across North America, especially in warm weather months. About 10% of them <a href="https://www.nssl.noaa.gov/education/svrwx101/thunderstorms/">become severe</a>, meaning they produce hail 1 inch or greater in diameter, winds gusting in excess of 50 knots (57.5 miles per hour), or a tornado.</p>
<p>The U.S. occasionally experiences rarer events: organized lines of thunderstorms with widespread damaging winds, known as derechos.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/341562/original/file-20200612-153862-17rxzao.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/341562/original/file-20200612-153862-17rxzao.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/341562/original/file-20200612-153862-17rxzao.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341562/original/file-20200612-153862-17rxzao.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341562/original/file-20200612-153862-17rxzao.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341562/original/file-20200612-153862-17rxzao.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341562/original/file-20200612-153862-17rxzao.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341562/original/file-20200612-153862-17rxzao.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Derechos occur fairly regularly over large parts of the U.S. each year, most commonly from April through August.</span>
<span class="attribution"><a class="source" href="https://www.spc.noaa.gov/misc/AbtDerechos/images/Jet_Stream_figs/derechoclimo.png">Dennis Cain/NOAA</a></span>
</figcaption>
</figure>
<p>Derechos occur mainly across the central and eastern U.S., where many locations are affected one to two times per year on average. They can produce significant damage to structures and sometimes cause “blowdowns” of millions of trees. Pennsylvania and New Jersey <a href="https://www.inquirer.com/weather/derecho-power-outages-peco-supercell-thunderstorms-philadelphia-weather-20200606.html">received the brunt</a> of a derecho on June 3, 2020, that killed four people and left nearly a million without power across the mid-Atlantic region.</p>
<p>In the West, derechos are less common, but Colorado – where I serve as state climatologist and <a href="https://scholar.google.com/citations?user=vfbhQHkAAAAJ&hl=en">director of the Colorado Climate Center</a> – experienced a <a href="https://www.coloradoan.com/story/news/2020/06/08/colorado-experiences-rare-derecho-produced-hurricane-force-winds/5317767002/">rare and powerful derecho</a> on June 6, 2020 that generated winds exceeding 100 miles per hour in some locations. And on August 10, 2020 a derecho rolled across Iowa, Wisconsin, Illinois and Indiana, generating rare “<a href="https://twitter.com/CNN/status/1292898789649461248">particularly dangerous situation” warnings</a> from forecasters and registering wind gusts as high as <a href="https://twitter.com/pppapin/status/1292874234725912577">130 miles per hour</a>.</p>
<p>Derechos have also been observed and analyzed in many other parts of the world, including Europe, Asia and South America. They are an important and active research area in meteorology. Here’s what we know about these unusual storms.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-6695cCRKmY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A massive derecho in June 2012 developed in northern Illinois and traveled to the mid-Atlantic coast, killing 22 and causing $4 billion to $5 billion in damages.</span></figcaption>
</figure>
<h2>Walls of wind</h2>
<p>Scientists have long recognized that organized lines of thunderstorms can produce widespread damaging winds. <a href="http://www.spc.noaa.gov/misc/AbtDerechos/hinrichs/JohnsDerechoStory.pdf">Gustav Hinrichs</a>, a professor at the University of Iowa, analyzed severe winds in the 1870s and 1880s and identified that many destructive storms were produced by straight-line winds rather than by tornadoes, in which winds rotate. Because the word “tornado,” of Spanish origin, was already in common usage, Hinrichs proposed “derecho” – Spanish for “straight ahead” – for damaging windstorms not associated with tornadoes. </p>
<p>In 1987, meteorologists defined what <a href="https://doi.org/10.1175/1520-0434(1987)002%3C0032:DWCIW%3E2.0.CO;2">qualified as a derecho</a>. They proposed that for a storm system to be classified as a derecho, it had to produce severe winds – 57.5 mph (26 meters per second) or greater – and those intense winds had to extend over a path at least 250 miles (400 kilometers) long, with no more than three hours separating individual severe wind reports. </p>
<p>Derechos are almost always caused by a type of weather system known as a <a href="https://www.weather.gov/jetstream/derecho_bowecho">bow echo</a>, which has the shape of an archer’s bow on radar images. These in turn are a specific type of <a href="https://doi.org/10.1175/AMSMONOGRAPHS-D-18-0001.1">mesoscale convective system</a>, a term that describes <a href="https://doi.org/10.1038/s43017-020-0057-7">large, organized groupings of storms</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1292938287296974856"}"></div></p>
<p>Researchers are studying whether and how climate change is affecting weather hazards from thunderstorms. Although some aspects of mesoscale convective systems, such as the amount of rainfall they produce, are very likely to change with continued warming, it’s not yet clear how future climate change may affect the likelihood or intensity of derechos. </p>
<h2>Speeding across the landscape</h2>
<p>The term “derecho” vaulted into public awareness in June 2012, when one of the most destructive derechos in U.S. history formed in the Midwest and <a href="https://www.spc.noaa.gov/misc/AbtDerechos/casepages/jun292012page.htm">traveled some 700 miles in 12 hours</a>, eventually making a direct impact on the Washington, D.C. area. This event killed 22 people and caused millions of power outages. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/341563/original/file-20200612-153822-1boc4jz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/341563/original/file-20200612-153822-1boc4jz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/341563/original/file-20200612-153822-1boc4jz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=665&fit=crop&dpr=1 600w, https://images.theconversation.com/files/341563/original/file-20200612-153822-1boc4jz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=665&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/341563/original/file-20200612-153822-1boc4jz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=665&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/341563/original/file-20200612-153822-1boc4jz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=835&fit=crop&dpr=1 754w, https://images.theconversation.com/files/341563/original/file-20200612-153822-1boc4jz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=835&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/341563/original/file-20200612-153822-1boc4jz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=835&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Top: Radar imagery every two hours, from 1600 UTC 29 June to 0400 UTC 30 June 2012, combined to show the progression of a derecho-producing bow echo across the central and eastern US. Bottom: Severe wind reports for the 29-30 June 2012 derecho, colored by wind speed.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s43017-020-0057-7">Schumacher and Rasmussen, 2020, adapted from Guastini and Bosart 2016</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Only a few recorded derechos had occurred in the western U.S. prior to June 6, 2020. On that day, a line of strong thunderstorms developed in eastern Utah and western Colorado in the late morning. This was unusual in itself, as storms in this region tend to be less organized and occur later in the day. </p>
<p>The thunderstorms continued to organize and moved northeastward across the Rocky Mountains. This was even more unusual: Derecho-producing lines of storms are driven by a pool of cold air near the ground, which would typically be disrupted by a mountain range as tall as the Rockies. In this case, the line remained organized.</p>
<p>As the line of storms emerged to the east of the mountains, it caused widespread wind damage in the Denver metro area and northeastern Colorado. It then strengthened further as it proceeded north-northeastward across eastern Wyoming, western Nebraska and the Dakotas. </p>
<p>In total there were nearly 350 reports of severe winds, including 44 of 75 miles per hour (about 34 meters per second) or greater. The strongest reported gust was 110 mph at Winter Park ski area in the Colorado Rockies. Of these reports, 95 came from Colorado – by far the most severe wind reports ever from a single thunderstorm system. </p>
<figure>
<img src="https://cdn.theconversation.com/static_files/files/1070/06jun20_warnings.gif?1591986529">
<figcaption><span class="caption">Animation showing the development and evolution of the 6-7 June 2020 western derecho. Radar reflectivity is shown in the color shading, with National Weather Service warnings shown in the colored outlines (yellow polygons indicate severe thunderstorm warnings). Source: Iowa Environmental Mesonet.</span></figcaption>
</figure>
<p>Coloradans are accustomed to big weather, including strong winds in the mountains and foothills. Some of these winds are generated by flow <a href="http://glossary.ametsoc.org/wiki/Downslope_windstorm">down mountain slopes</a>, localized thunderstorm <a href="https://www.weather.gov/bmx/outreach_microbursts">microbursts</a>, or even “<a href="https://theconversation.com/when-does-a-winter-storm-become-a-bomb-cyclone-113452">bomb cyclones</a>.” Western thunderstorms more commonly produce hailstorms and tornadoes, so it was very unusual to have a broad swath of the state experience damaging straight-line winds that extended from west of the Rockies all the way to the Dakotas. </p>
<h2>Damage comparable to a hurricane</h2>
<p>Derechos are challenging to predict. On days when derechos form, it is often uncertain whether any storms will form at all. But if they do, the chance exists for explosive development of intense winds. Forecasters did not anticipate the historic June 2012 derecho until it was already underway.</p>
<p>For the western derecho on June 6, 2020, outlooks showed an enhanced potential for severe storms in Nebraska and the Dakotas two to three days in advance. However, the outlooks didn’t highlight the potential for destructive winds farther south in Colorado until the morning that the derecho formed.</p>
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<p>Once a line of storms has begun to develop, however, the National Weather Service routinely issues highly accurate severe thunderstorm warnings 30 to 60 minutes ahead of the arrival of intense winds, alerting the public to take precautions. </p>
<p>Communities, first responders and utilities may have only a few hours to prepare for an oncoming derecho, so it is important to know <a href="https://www.weather.gov/media/top/Methods%20to%20Receive%20Warnings_monday.pdf">how to receive severe thunderstorm warnings</a>, such as TV, radio and smartphone alerts, and to take these warnings seriously. Tornadoes and tornado warnings often get the most attention, but lines of severe thunderstorms can also pack a major punch.</p>
<p><em>This is an updated version of an article originally published on June 15, 2020.</em></p><img src="https://counter.theconversation.com/content/140319/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Russ Schumacher receives funding from the National Science Foundation, National Oceanic and Atmospheric Administration for research on high impact weather, and from the Colorado Agricultural Experiment Station for research, education, and outreach related to Colorado's climate.</span></em></p>Hurricane and tornado winds spin in circles, but there’s another, equally dangerous storm type where winds barrel straight ahead. They’re called derechos, and are most common in summer.Russ Schumacher, Associate Professor of Atmospheric Science and Colorado State Climatologist, Colorado State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1329552020-03-05T12:46:25Z2020-03-05T12:46:25ZTornadoes that strike at night are more deadly and require more effective warning systems<figure><img src="https://images.theconversation.com/files/318742/original/file-20200304-66112-6c9etz.jpg?ixlib=rb-1.1.0&rect=49%2C0%2C5472%2C3620&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Salvaging items from a destroyed home near Lebanon, Tenn., March 3, 2020, after tornadoes ripped across the state. </span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Severe-Weather-Tennessee/c50fad325e494210a0f1ddf403c3c847/18/0">AP Photo/Mark Humphrey</a></span></figcaption></figure><p>During the hours after midnight on March 3, 2020, tragedy struck middle Tennessee when <a href="https://forecast.weather.gov/product.php?site=NWS&issuedby=OHX&product=PNS&format=CI&version=1&glossary=0">a tornado</a> ripped through the region, traveling over 50 miles from West Nashville to near Gordonsville. <a href="https://www.washingtonpost.com/weather/2020/03/03/how-deadly-destructive-tornadoes-ravaged-nashville-tuesday/">Another tornado</a> formed from the same system shortly afterward, near Cookeville. Preliminary damage assessments estimate that the most intense portion of this storm produced a <a href="https://www.weather.gov/ohx/DamageSurveysfromMarch3">strong EF3 tornado</a>, with winds up to 165 miles per hour.</p>
<p>At the time of this writing, <a href="https://weather.com/news/news/2020-03-03-tennessee-tornado-damage-deaths-severe-storms">25 people are confirmed dead</a>. At least 18 of those victims were located at the end of the storm’s path. Dozens more people are still missing. </p>
<p>For many Americans, the thought of an overnight tornado is just a nightmare. But for Tennessee residents, it is a regular and terrifying reality. <a href="https://doi.org/10.1175/2008WAF2222132.1">Nearly half of tornadoes that occur here</a> strike when the sun is down. </p>
<p>We are hazardous weather climatologists working in and researching the climate of <a href="https://scholar.google.com/citations?user=BZn_vToAAAAJ&hl=en">middle</a> and <a href="https://scholar.google.com/citations?user=LvpAEa0AAAAJ&hl=en">east</a> Tennessee. We analyze data to tell a story about hazards posed by local climatic conditions, and the public’s perception of and preparation for those hazards. As extreme events unfold, we see these intersections play out in real time, just as we did in this recent disaster.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6XJlU6UH1Qw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Video of the tornado that touched down north of downtown Nashville on March 3, 2020.</span></figcaption>
</figure>
<h2>Tornado timing</h2>
<p>Tornadoes in Tennessee and the Southeast region are unique, in that a relatively large proportion of tornadoes <a href="https://www.ncdc.noaa.gov/climate-information/extreme-events/us-tornado-climatology/trends">occur at night</a>. Nighttime events, as well as those outside of the spring season, are common in this region because the <a href="https://pdfs.semanticscholar.org/07e3/adc4dffe98cc9e17e8b494c00f91d748151d.pdf">ingredients for storms are different</a> from those that occur in the area of the central and southern Plains typically called “<a href="https://www.accuweather.com/en/weather-news/what-is-tornado-alley-2/432271">Tornado Alley</a>.”</p>
<p>In a 2019 study with social science collaborators, we surveyed over 1,800 Tennessee residents about their perceptions of local tornado climatology. Some participants recognized that about half of their tornadoes happened at night, but many others believed that <a href="https://doi.org/10.1371/journal.pone.0219897">either few or all twisters struck after dark</a>. </p>
<p>Researchers are particularly concerned about how the public understands and manages the threat of nighttime tornadoes because these events are <a href="https://doi.org/10.1175/2008WAF2222132.1">more than twice as likely to be fatal</a> than those that occur during the day. There are a few potential explanations for heightened nighttime fatality rates. </p>
<p>First, tornadoes at night are harder for storm spotters and the public to see. Second, people may be asleep and not receive a tornado warning. Finally, at night people are more likely to be in structures such as mobile homes, where they are more vulnerable than they would be in an office building or a structure tied to a foundation during a daytime storm.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_5TiTfuvotc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">What to do if a tornado warning sounds in your area.</span></figcaption>
</figure>
<h2>Waking to a warning</h2>
<p>Weather forecasters <a href="https://www.washingtonpost.com/weather/2020/03/03/how-deadly-destructive-tornadoes-ravaged-nashville-tuesday/">issued warnings</a> as the March 3 tornadoes took form, but it’s hard to know whether middle Tennessee residents awoke to sirens, cellphone alerts or other alarms.</p>
<p>Our research suggests that many Tennessee residents <a href="https://doi.org/10.1175/WCAS-D-17-0114.1">may not receive advance warning</a> for a tornado at night. When asked whether and from where they would most likely receive a tornado warning at night, fewer than half of our survey participants believed they would receive such a warning. </p>
<p>People receive weather-related warnings in a variety of ways, some of which are not well suited for nighttime events. For example, some of our survey participants listed sources like <a href="https://doi.org/10.1175/WCAS-D-17-0114.1">social media and local television</a>, but these outlets can’t wake people from sleep.</p>
<p>During the March 3 event, these sources were active and informative for people who were already awake – especially the Twitter account <a href="https://twitter.com/nashseverewx">@NashSevereWx</a>, which works closely with the National Weather Service to disseminate emergency information. Local broadcast meteorologists were continuously on air from the time initial warnings were issued around midnight until the threat was over <a href="https://twitter.com/NashSevereWx/status/1234803346256617473">hours later</a>. However, many middle Tennesseans <a href="https://www.newschannel5.com/news/nes-confirms-47k-outages-crews-working-to-restore-power">lost power during the storm</a>, which potentially reduced their access to broadcast and social media warnings.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1234709986158292992"}"></div></p>
<p>Sirens are <a href="https://doi.org/10.1175/WAF-D-19-0090.1">another popular warning source</a> for Tennessee residents, but relying on them to wake people during a nighttime event is unsafe. Sirens are only meant to alert <a href="https://www.weather.gov/dvn/sirenFAQ">people who are outside</a> about impending weather hazards, not those who are indoors. </p>
<p>In the early morning hours on March 3, some people heard sirens across middle Tennessee and heeded the warning. Others wondered whether the sirens were working properly and <a href="https://twitter.com/NashSevereWx/status/1234737401978814464">tweeted @NashSevereWx</a> to gather information on whether warnings were still in effect. </p>
<p><a href="https://www.fcc.gov/consumers/guides/wireless-emergency-alerts-wea">Wireless Emergency Alerts</a>, which send geographically targeted, text-like messages to cellphones, are a relatively new way to spread warning information. However, in interviews we conducted in 2017, Tennessee residents expressed concern about relying on these alerts because of <a href="https://doi.org/10.1175/WAF-D-19-0090.1">poor cell coverage in rural areas</a>. Wireless alerts were used to broadcast tornado warnings across middle Tennessee on March 3, but may not have been received in some locations due to <a href="https://twitter.com/WHSVaubs/status/1235085877983862785">cellular service interruptions</a>. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/318747/original/file-20200304-66084-1nrd99a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/318747/original/file-20200304-66084-1nrd99a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=814&fit=crop&dpr=1 600w, https://images.theconversation.com/files/318747/original/file-20200304-66084-1nrd99a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=814&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/318747/original/file-20200304-66084-1nrd99a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=814&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/318747/original/file-20200304-66084-1nrd99a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1023&fit=crop&dpr=1 754w, https://images.theconversation.com/files/318747/original/file-20200304-66084-1nrd99a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1023&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/318747/original/file-20200304-66084-1nrd99a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1023&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A wireless emergency alert message on an Apple smartwatch.</span>
<span class="attribution"><a class="source" href="https://www.fema.gov/media-library/assets/images/170944">FEMA/Justin Singer</a></span>
</figcaption>
</figure>
<p>Experts in Tennessee recommend having multiple methods for receiving warnings at night. This strategy allows for backup options when power goes out, cellphones go down or other unforeseen circumstances occur. In a forecast discussion on the evening of March 2, the National Weather Service office in Nashville urged residents to “<a href="https://mesonet.agron.iastate.edu/wx/afos/p.php?pil=AFDOHX&e=202003030414">have a few reliable methods</a> for receiving warnings overnight in the event they are issued.”</p>
<h2>What worries forecasters</h2>
<p>Because tornadoes at night are a part of the climatology in Tennessee, National Weather Service forecasters here are <a href="https://doi.org/10.1175/WAF-D-19-0090.1">well aware of the associated communication challenges</a>. One Tennessee forecaster we interviewed for our research plainly stated that tornadoes at night “scare the hell out of me” for the public, because fatalities “are a given.” </p>
<p>Weather professionals here are concerned about reaching a sleeping public, and noted the importance of stressing projected overnight risks before residents go to sleep. Forecasters hope that wireless emergency alerts can help them reach more people during nighttime events. </p>
<p>During a tornado event, communication goes two ways. Forecasters relay risk information to the public, while members of the public provide “ground truth” for those forecasts, mainly through social media. Knowing what is happening on the ground is essential during more complex forecasts. In our interviews, forecasters said that this flow of information tends to slow to a crawl at night, <a href="https://doi.org/10.1080/24694452.2019.1670042">leaving them in the dark</a> about actual conditions outside.</p>
<p>In our research, we have seen that National Weather Service offices in Tennessee have <a href="https://doi.org/10.1080/24694452.2019.1670042">strong relationships with media outlets</a> and other partners, and are genuinely concerned about improving <a href="https://doi.org/10.1175/WAF-D-19-0090.1">public safety</a>. As we write, they are busy <a href="https://twitter.com/NWSNashville/status/1234978442040373248">surveying the damage</a> in middle Tennessee to better understand the tornadoes that wreaked havoc in their community. By building a bridge between forecasters, their partners and their community, we hope to help further their work.</p>
<p>[<em>Insight, in your inbox each day.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=insight">You can get it with The Conversation’s email newsletter</a>.]</p><img src="https://counter.theconversation.com/content/132955/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kelsey Ellis received funding from the VORTEX-SE program of the National Oceanic and Atmospheric Administration for this work.</span></em></p><p class="fine-print"><em><span>Alisa Hass 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>In the Southeast US, tornadoes strike at night more often than in other regions. This poses special challenges for getting early warnings to the public.Kelsey Ellis, Associate Professor of Geography, University of TennesseeAlisa Hass, Assistant Professor of Geoscience, Middle Tennessee State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1329482020-03-04T11:57:57Z2020-03-04T11:57:57ZIf you want to help after the Nashville tornadoes, give cash, not clothing and other stuff<figure><img src="https://images.theconversation.com/files/318463/original/file-20200303-66060-1fmbpt7.jpg?ixlib=rb-1.1.0&rect=1269%2C696%2C4194%2C2162&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The wreckage in Nashville was extreme.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/APTOPIX-Severe-Weather-Tennessee/cd8aecf401bf4e69a12207e8cdbeec1c/1/0">AP Photo/Wade Payne</a></span></figcaption></figure><p>Powerful <a href="https://apnews.com/795688aab981d4e8220042c20e095b55">storms and tornadoes</a> left a trail of devastation as they ripped through Nashville on March 3, killing 25 people, injuring dozens more and leaving hundreds homeless. As first responders and residents of the Tennessee city searched for the missing, assessed the damage and began to pick up the pieces, <a href="https://www.wsmv.com/how-to-help-in-the-stir-of-tennessee-tornado-disaster/article_5c3ba50c-5d68-11ea-bcc3-3f108d0bcc62.html">relief efforts started taking shape right away</a>. </p>
<p>In the aftermath of such tragedies, the urge to help is laudable. Some organizations and community groups don’t want to wait before organizing donation drives. Yet, as someone who has studied how professionals and local communities <a href="https://scholar.google.com/citations?user=zJlFCUQAAAAJ&hl=en">respond to emergencies</a>, I’ve seen time and again how well-intentioned efforts to donate goods to distant disasters can go wrong.</p>
<p>Donations of food, clothing, toiletries and diapers are often the last thing that is needed in disaster-affected areas. </p>
<p>Delivering things that people need on the ground simply doesn’t help disaster-struck communities as much as giving them <a href="https://www.cnbc.com/2017/09/30/puerto-rico-donations-may-create-a-second-disaster-so-just-send-cash.html">money to buy what they need</a>. What’s more, truckloads of blue jeans and cases of Lunchables can actually <a href="https://www.vox.com/the-goods/2018/11/15/18096792/donating-disasters-cash-vs-canned-goods">interfere with official relief efforts</a>.</p>
<p>If you want to do the greatest good, send money.</p>
<h2>Transportation trouble</h2>
<p>Disaster relief efforts repeatedly provide lessons in good intentions gone wrong.</p>
<p>At best, donating bottled water, blankets and other stuff can augment official efforts and provide the locals with some additional comfort, especially when those donations come from nearby. When <a href="https://www.congress.gov/congressional-report/109th-congress/senate-report/322/1">various levels of government failed</a> to meet the needs of Hurricane Katrina victims, for example, <a href="https://www.gao.gov/products/GAO-06-297T">community, faith-based and private sector organizations</a> stepped in to <a href="https://dx.doi.org/10.1177%2F003335490712200319">fill many of the gaps</a>.</p>
<p>How can these donations cause more harm than good? By <a href="https://www.devex.com/news/thanks-but-no-thanks-unwanted-goods-flood-disaster-struck-developing-countries-89458">raising the cost</a> of the response cycle. Everything from collecting, sorting, packaging and shipping bulky items across long distances to sorting, warehousing and distributing them upon arrival costs a lot of money.
Delivering this aid is tough in disaster areas since <a href="https://www.npr.org/sections/thetwo-way/2017/09/28/554297787/puerto-rico-relief-goods-sit-undistributed-at-ports">transportation infrastructure</a>, such as airports, roads and bridges, are likely to be damaged by the disaster or busy with the surge of incoming first responders, relief shipments and equipment.</p>
<p>This is true in Nashville, where the storms and tornadoes caused massive power outages, filled roads with debris and <a href="https://www.ainonline.com/aviation-news/business-aviation/2020-03-03/nashville-airport-hammered-tornado">severely damaged Tennessee’s biggest airport</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/318465/original/file-20200303-66106-15ye0l4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/318465/original/file-20200303-66106-15ye0l4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/318465/original/file-20200303-66106-15ye0l4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/318465/original/file-20200303-66106-15ye0l4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/318465/original/file-20200303-66106-15ye0l4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/318465/original/file-20200303-66106-15ye0l4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/318465/original/file-20200303-66106-15ye0l4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/318465/original/file-20200303-66106-15ye0l4.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">Tennessee Gov. Bill Lee, right and Tennessee Commerce and Insurance Commissioner Hodgen Mainda surveyed the damage.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Severe-Weather-Tennessee/48f5426862dd4d94b904dcc61e687d4d/7/0">AP Photo/Travis Loller</a></span>
</figcaption>
</figure>
<h2>Dumping grounds</h2>
<p>At worst, disaster zones become <a href="https://www.cbsnews.com/news/when-disaster-relief-brings-anything-but-relief/">dumping grounds</a> for <a href="http://www.slate.com/articles/news_and_politics/foreigners/2013/11/how_to_help_typhoon_haiyan_survivors_in_the_philippines_the_only_donation.html">a lot of junk</a> that can delay actual relief efforts and harm local economies.</p>
<p>After the 2004 South Asian tsunami, shipping containers full of <a href="http://www.slate.com/articles/news_and_politics/foreigners/2013/11/how_to_help_typhoon_haiyan_survivors_in_the_philippines_the_only_donation.html">ill-suited items</a> such as used high-heeled shoes, ski gear and expired medications poured into the affected countries. This junk clogged ports and roads, polluting already ravaged areas and <a href="https://hbr.org/2006/11/disaster-relief-inc">diverting personnel</a>, trucks and storage facilities from actual relief efforts.</p>
<p>After the 2010 earthquake in Haiti, many untrained and uninvited American volunteers bringing unnecessary goods ended up <a href="http://www.nbcnews.com/id/34958965/ns/world_news-haiti/t/disaster-do-gooders-can-actually-hinder-help/#.Waq6YdOGPeQ">needing assistance themselves</a>.</p>
<p>One study led by <a href="https://ascelibrary.org/doi/abs/10.1061/(ASCE)NH.1527-6996.0000113">José Holguín-Veras</a>, a Rensselaer Polytechnic Institute expert on humanitarian logistics, found that 50% to 70% of the goods that arrive during these emergencies should never have been sent and interfere with recovery efforts. After the 2011 Joplin, Missouri, tornado and the Tōhoku, Japan, earthquake, for example, excessive donations of <a href="http://dx.doi.org/10.1016/j.jom.2012.08.003">clothing and blankets</a> tied up relief personnel.</p>
<p>Relief workers consider these well-meaning but inconvenient donations as a “<a href="http://www.newsweek.com/75-million-stuff-148091">second-tier disaster</a>” due to the disruption they cause.</p>
<h2>What else can you do?</h2>
<p>Instead of shipping your hand-me-downs, donate money to trusted and established organizations with extensive experience and expertise and local ties.</p>
<p><a href="https://theconversation.com/how-to-select-a-disaster-relief-charity-83928">Give to groups</a> that make it clear where the money will go. Choose relief efforts that will procure supplies near the disaster area, which will help the local economy recover. You can also consult organizations like <a href="https://www.charitynavigator.org/">Charity Navigator</a> that evaluate charities’ financial performance.</p>
<p>Many humanitarian aid organizations themselves have increasingly adopted cash-based approaches in recent years, though money remains a <a href="https://www.theguardian.com/global-development-professionals-network/2016/jan/22/cash-transfers-only-6-of-humanitarian-spending-whats-the-hold-up">small share</a> of overall humanitarian aid worldwide.</p>
<p>Evaluations of the effectiveness of <a href="http://www.cashlearning.org/resources/library/1106-cash-based-approaches-in-humanitarian-emergencies-a-systematic-review-april-2016">such programs vary</a> and are <a href="http://pubs.iied.org/10759IIED/">context-dependent</a>. Nonetheless, <a href="https://www.odi.org/publications/9454-state-evidence-humanitarian-cash-transfers">emerging evidence suggests</a> that disbursing cash is often the best way to help people in disaster zones get the food and shelter they need.</p>
<p>What’s more, the World Food Program and the U.N. High Commissioner for Refugees say that <a href="https://reliefweb.int/report/world/examining-protection-and-gender-cash-and-voucher-transfers-case-studies-world-food">people affected by disasters tend to prefer</a> cash over in-kind aid due to the <a href="https://www.odi.org/publications/7406-cash-transfers-social-protection-community-participatory-development">dignity, control and flexibility</a> it gives them. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1234911344064856064"}"></div></p>
<h2>Some exceptions</h2>
<p>There are a few notable exceptions to this advice on avoiding in-kind donations. </p>
<p>If you live in or near the affected area, it is helpful to consider dropping the specific items victims are requesting at local food banks, shelters and other community organizations. Just make sure that nothing you’re giving away will spoil quickly.</p>
<p>For instance, the <a href="https://twitter.com/NashvilleResist/status/1234937233716776968">Community Resource Center Nashville</a> has said it is accepting donations of personal hygiene items, bleach, trash bags, gloves and box cutters. The Community Foundation of Middle Tennessee has activated the <a href="https://midtnemergency.kimbia.com/midtnemergency2020">Middle Tennessee Emergency Response Fund</a> to support the affected communities, and is accepting donations. So is the local <a href="https://www.wkrn.com/news/nashville-tornado/how-to-help-donation-volunteers-needed-following-nashville-tornado/">United Way</a>. Other organizations, including <a href="https://www.hon.org/opportunity/a0C1H00001asG2t?">Hands On Nashville</a>, are seeking volunteers.</p>
<p>When disaster strikes, the urge to help is admirable. Yet this impulse should be channeled to do the greatest good. So please, if you would like to help from afar, let the professionals procure goods and services. Instead, donate money and listen to what people on the ground say they need.</p>
<p>And don’t stop giving after the disaster stops making headlines. A full recovery will take time and support long after the emergency responders and camera crews have moved on.</p>
<p><em>This is an updated version of an article published on <a href="https://theconversation.com/want-to-help-after-hurricanes-give-cash-not-diapers-103069">Sept. 13, 2018</a>.</em></p><img src="https://counter.theconversation.com/content/132948/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julia Brooks 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>Donated goods often not only fail to help those in actual need but cause congestion, tie up resources and further hurt local economies.Julia Brooks, Furman Public Policy Scholar, New York UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1235662019-12-10T13:57:28Z2019-12-10T13:57:28ZSmashed cars, burnt trees, soggy insulation: Post-disaster cleanup is expensive, time-consuming and wasteful<figure><img src="https://images.theconversation.com/files/437026/original/file-20211211-159504-lrdlj5.jpg?ixlib=rb-1.1.0&rect=8%2C8%2C2986%2C1989&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A collapsed building in Mayfield, Ky., after a tornado hit the town on Dec. 11, 2021.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/general-view-of-the-collapsed-mayfield-consumer-products-news-photo/1237162507">Brett Carlsen/Getty Images</a></span></figcaption></figure><p>Communities across the U.S. Southeast and Midwest will be assessing damage from the deadly and widespread <a href="https://www.nytimes.com/live/2021/12/11/us/tornadoes-midwest-south#arkansas-tornado-nursing-home-monette">tornado outbreak on Dec. 10-11, 2021</a> for some time. But it’s clear that the cleanups will take months, and possibly years.</p>
<p>Dealing with enormous quantities of debris and waste materials is one of the most significant challenges for communities in the wake of natural disasters. Often this task overwhelms local waste managers, leaving waste untouched for weeks, months or even years. </p>
<p>The most destructive and costliest wildfire in California’s history, the Camp Fire, killed 85 people and <a href="https://www.fire.ca.gov/incidents/2018/11/8/camp-fire/">destroyed nearly 19,000 structures</a> in November 2018. A year later, crews were still collecting and carrying away piles of wood, metals, appliances, contaminated soil, toxic household chemicals, and other debris and waste totaling <a href="https://storage.googleapis.com/proudcity/buttecountycarecovers/uploads/2019/10/DR-4407-CA-Recovery-Update-043-10.23.19.pdf">more than 3.2 million metric tons</a> – roughly the weight of 2 million cars.</p>
<p>Hurricane Michael, which hit Florida in October 2018, left about 13 million cubic meters of debris. To visualize what that looks like, picture a pile of 13 million boxes, each the size of a washer and dryer. More than a year later, crews were <a href="https://fox8.com/2019/10/10/one-year-later-florida-panhandle-struggles-to-recover-from-hurricane-michael/">still removing the waste</a>. </p>
<p>As researchers who study <a href="https://scholar.google.com/citations?user=vUhXX-MAAAAJ&hl=en">urban engineering</a>, <a href="https://scholar.google.com/citations?user=rytzGosAAAAJ&hl=en">disaster management and planning</a>, and <a href="https://scholar.google.com/citations?user=J8dGrPwAAAAJ&hl=en">waste management</a>, we see this as a critical and under-studied problem. Disasters will continue to happen and the losses they cause will continue to grow as a result of climate change, population growth, urbanization, deforestation and aging infrastructures. Societies urgently need better strategies for dealing with the wastes these events leave behind.</p>
<figure class="align-center ">
<img alt="Woman sorts through soggy materials in roofless building" src="https://images.theconversation.com/files/437022/original/file-20211211-25-hl1k6x.jpg?ixlib=rb-1.1.0&rect=15%2C7%2C5267%2C3508&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437022/original/file-20211211-25-hl1k6x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437022/original/file-20211211-25-hl1k6x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437022/original/file-20211211-25-hl1k6x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437022/original/file-20211211-25-hl1k6x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437022/original/file-20211211-25-hl1k6x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437022/original/file-20211211-25-hl1k6x.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">In the aftermath of Hurricane Ida, Amy Voisin cleans up a heavily damaged bowling alley in Houma, La. on Aug. 31, 2021.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/TropicalStorm/ab834bc1b1c8441abdca4e334bdfc3cb/photo">AP Photo/David J. Phillip</a></span>
</figcaption>
</figure>
<h2>Trails of wreckage</h2>
<p>Climate-related disasters like floods, landslides, storms, wildfires, and extreme hot and cold waves afflict millions of people around the world. These events have been increasing over time, particularly over the past several decades, and so have the losses they cause.</p>
<p>In 2020, the U.S. experienced a record-setting <a href="https://www.noaa.gov/stories/record-number-of-billion-dollar-disasters-struck-us-in-2020">22 natural disasters</a> that each caused at least a billion dollars in damages. For 2021, the count stood at <a href="https://www.noaa.gov/news/us-hit-with-18-billion-dollar-disasters-so-far-year">18 such events through early October</a>. The mid-December tornado outbreak doubtlessly will add to it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/437023/original/file-20211211-140267-1tvh5qs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing locations of major storms, flooding and wildfires across the US." src="https://images.theconversation.com/files/437023/original/file-20211211-140267-1tvh5qs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/437023/original/file-20211211-140267-1tvh5qs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=331&fit=crop&dpr=1 600w, https://images.theconversation.com/files/437023/original/file-20211211-140267-1tvh5qs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=331&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/437023/original/file-20211211-140267-1tvh5qs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=331&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/437023/original/file-20211211-140267-1tvh5qs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=416&fit=crop&dpr=1 754w, https://images.theconversation.com/files/437023/original/file-20211211-140267-1tvh5qs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=416&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/437023/original/file-20211211-140267-1tvh5qs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=416&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Eighteen separate billion-dollar weather and climate disasters struck the U.S. from January-September 2021.</span>
<span class="attribution"><a class="source" href="https://www.noaa.gov/news/us-hit-with-18-billion-dollar-disasters-so-far-year">NOAA</a></span>
</figcaption>
</figure>
<p>Disasters commonly produce thousands to millions of tons of debris in a single event. For example, waste from hurricanes includes vegetation, such as trees and shrubs; municipal solid waste, such as household garbage; construction and demolition materials; vehicles; and household hazardous materials, including paints, cleaning agents, pesticides and pool chemicals. </p>
<p>Debris from wildfires largely consists of ash, contaminated soils, metal and concrete, along with other structural debris and household hazardous items such as paints, cleaners, solvents, oils, batteries, herbicides and pesticides.</p>
<h2>Dangerous and in the way</h2>
<p>Debris collection and cleanup following a disaster is a slow, expensive and dangerous process. First, crews clear out debris from roads used for rescue efforts. They then move the material to temporary storage areas. No one has yet invented a way to easily sort or contain hazardous materials, so they remain mixed into the debris mass. This poses major challenges for reusing and recycling post-disaster waste. </p>
<p>Beyond direct health and safety risks, debris also threatens the environment. It can emit air pollutants and contaminate groundwater, surface waters and soil. Uncollected debris and waste can hamper rescue and recovery efforts and slow down rebuilding efforts.</p>
<p>As an example, when Hurricane Katrina flooded New Orleans in 2005, it left behind an estimated <a href="https://fas.org/sgp/crs/misc/RL33477.pdf">75 million cubic meters of waste</a> that interfered with and slowed down recovery efforts. The debris included close to 900,000 white goods, such as refrigerators, 350,000 cars and more than 16,000 metric tons of rotten meat. Cleanup costs were estimated at roughly US$4 billion.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/73OFvzz68Es?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Residents of Liberty City, Florida complain about dirt and odors from debris processing after Hurricane Irma in 2017.</span></figcaption>
</figure>
<h2>Toward reusing disaster waste</h2>
<p>At an <a href="https://csun.uic.edu/publications/files/NSF_PDMEM_Final_Report.pdf">expert workshop</a> that we organized in 2019, we identified steps for sustainably managing disaster debris and waste. As we see it, the key tasks are to (1) identify what is contained in these wastes; (2) find better approaches to recycling and reuse; (3) design new technologies to identify hazardous components and sort the different types of waste; and (4) develop markets to promote reuse and recycling.</p>
<p>Today public officials and planners know little about the amount and types of materials generated during disasters – what they contain, in what proportions, whether they are large and sortable versus fine and mixed, and how much can be reused or recycled. Developing new technologies and management approaches that can assist debris characterization, reuse and recycling should be a top priority.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/305893/original/file-20191209-90609-13xdsmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/305893/original/file-20191209-90609-13xdsmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/305893/original/file-20191209-90609-13xdsmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/305893/original/file-20191209-90609-13xdsmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/305893/original/file-20191209-90609-13xdsmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/305893/original/file-20191209-90609-13xdsmn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/305893/original/file-20191209-90609-13xdsmn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/305893/original/file-20191209-90609-13xdsmn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&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 remains of a mobile home park in Sylmar, California after 480 of the park’s 600 mobile homes were burned in the November 2008 Sayre Fire.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Burned_mobile_home_neighborhood_in_California_edit.jpg">FEMA/Wikipedia</a></span>
</figcaption>
</figure>
<p>For example, drones and autonomous sensing technologies can be combined with artificial intelligence to estimate amounts and quality of debris, the types of materials it contains and how it can be repurposed rapidly. Technologies that allow for fast sorting and separation of mixed materials can also speed up debris management operations. </p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p>
<p>Turning the problem around, creating new sustainable construction materials – especially in disaster-prone areas – will make it easier to repurpose debris after disasters. </p>
<p>Finally, new business models can help generate demand for and access to waste and recycled products. With proper sorting, some disaster materials can be used to make new products or materials. For example, downed whole trees can become timber resources for furniture makers. Today, opportunities to match materials with markets are wasted – pun intended.</p>
<p><em>This is an updated version of an <a href="https://theconversation.com/millions-of-burnt-trees-and-rusted-cars-post-disaster-cleanup-is-expensive-time-consuming-and-wasteful-123566">article originally published</a> on Dec. 10, 2019.</em></p><img src="https://counter.theconversation.com/content/123566/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sybil Derrible receives funding from the National Science Foundation and the Illinois Department of Transportation. In Fall 2019, he was a Visiting Professor at the University of Transport Technology in Hanoi (Vietnam),</span></em></p><p class="fine-print"><em><span>Juyeong Choi receives funding from the National Science Foundation, Natural Hazards Center, and the Florida Department of Transportation. He is an Assistant Professor in Civil and Environmental Engineering, FAMU-FSU College of Engineering. </span></em></p><p class="fine-print"><em><span>Nazli Yesiller receives funding from the National Science Foundation, California Air Resources Board, California Department of Resources Recycling and Recovery, and W.M. Keck Foundation. </span></em></p>Government agencies have detailed plans for responding to disasters, like the Dec. 10-11, 2021 tornados. But one issue doesn’t get enough attention: cleaning up the mess left behind.Sybil Derrible, Associate Professor of Sustainable Infrastructure Systems, University of Illinois ChicagoJuyeong Choi, Assistant Professor, Florida A&M University-Florida State University College of Engineering, Florida State UniversityNazli Yesiller, Director, Global Waste Research Institute, California Polytechnic State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1229102019-09-03T18:04:07Z2019-09-03T18:04:07ZDamage estimates for hurricanes like Dorian don’t capture the full cost of climate change-fueled disasters<figure><img src="https://images.theconversation.com/files/290760/original/file-20190903-175691-osz1nv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cars sit submerged in water from Hurricane Dorian in Freeport, Bahamas.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Bahamas-Tropical-Weather/c33e35acc57449a5b6a701b73564bf7c/3/0">AP Photo/Ramon Espinosa</a></span></figcaption></figure><p><a href="https://insideclimatenews.org/news/03092019/hurricane-dorian-climate-change-stall-record-wind-speed-rainfall-intensity-global-warming-bahamas">Scientists say climate change</a> is causing powerful hurricanes like Dorian to increasingly stall over coastal areas, which leads to heavy flooding. Officials in the Bahamas <a href="https://www.nbcnews.com/news/weather/damage-bahamas-will-be-unprecedented-storm-unleashes-massive-flooding-n1048856">feared “unprecedented” devastation</a> after Dorian hovered over the islands for two days, pummeling it with rain. </p>
<p>But beyond more intense and slow-moving hurricanes, the warming climate <a href="https://www.huffingtonpost.com/entry/opinion-climate-change-deaths_us_5c101e14e4b0ac5371799b1c">has been blamed</a> for <a href="https://www.ncbi.nlm.nih.gov/pubmed/28663496">causing a sharp uptick</a> in all types of extreme weather events across the country, from <a href="https://www.theatlantic.com/science/archive/2019/07/climate-change-500-percent-increase-california-wildfires/594016/">explosive wildfires in California</a> to <a href="https://earther.gizmodo.com/this-springs-flooding-crisis-is-part-of-a-bigger-patter-1835092237">severe flooding across the U.S.</a> and <a href="https://www.climate.gov/USdrought2018">extensive drought</a> in the Southwest.</p>
<p>Late last year, the <a href="https://www.cnn.com/2018/11/23/health/climate-change-report-bn/index.html">media blared</a> that these and other consequences of climate change <a href="https://www.vox.com/2018/11/24/18109883/climate-report-2018-national-assessment">could cut U.S. GDP</a> by 10% by the end of the century – “more than double the losses of the Great Depression,” as <a href="https://www.nytimes.com/2018/11/23/climate/us-climate-report.html">The New York Times intoned</a>. That figure was drawn from a single figure in the U.S. government’s <a href="https://nca2018.globalchange.gov">Fourth National Climate Assessment</a>. (Disclosure: I reviewed that report and was the vice chair on the third one, released in 2014.)</p>
<p>If that sounds scary, I have good news and bad news. The good news is that that figure was drawn incorrectly from a significant misreading of the report – which actually offered a range of a loss of GDP from as low as 6% to as high as 14% by 2090.</p>
<p>The bad news, however, is that a more meaningful assessment of the costs of climate change – using basic economic principles <a href="https://gyohe.faculty.wesleyan.edu">I teach to undergrads</a> – is a hell of a lot scarier.</p>
<h2>Tallying the costs</h2>
<p>First, let’s look at how government agencies, insurance companies and the media calculate and report on the economic costs of disasters. </p>
<p>According to the National Oceanic and Atmospheric Administration, in 2018 Hurricanes Michael and Florence each caused about US$25 billion in damages, <a href="https://www.noaa.gov/news/2018-was-4th-hottest-year-on-record-for-globe">contributing to a total toll of $91 billion</a> from that year’s weather and climate disasters. In 2017, the NOAA’s total was even bigger: $306 billion, <a href="https://www.climate.gov/news-features/blogs/beyond-data/2017-us-billion-dollar-weather-and-climate-disasters-historic-year">due to the massive destruction</a> from Hurricanes Harvey, Irma and Maria. </p>
<p>But these tallies are not really valid measures of economic damage. Instead, they simply reflect estimates of what people think will need to be invested to rebuild what was damaged or destroyed in the storms, floods or fires.</p>
<p>To really understand the economic costs of an extreme weather event, it’s important to consider all the investment that is being “crowded out” or lost to cover those rebuilding costs. Put another way, there’s only so much money to go around. And that $25 billion being used to rebuild means $25 billion is not being used for other public and private investment opportunities that are more forward-looking or more likely to promote growth.</p>
<h2>Accounting for growth</h2>
<p>Instead, I believe a fundamentally more sound way to do this is to use something called “growth accounting.”</p>
<p><a href="https://economics.mit.edu/files/7183">Growth accounting</a> incorporates the productive use of capital and innovation into the equation. The question we want to ask is what happens to GDP growth when recovery efforts from extreme events crowd out productive investments, like building new factories or roads and bridges.</p>
<p>Returning to NOAA’s estimated losses for 2017 and 2018, productive investment fell about $400 billion in total in those years as a result. That is, had those disasters not happened, investment would have been that much higher. And that diminished investment translates into less growth in gross domestic product – a measure of all an economy produces in a given period.</p>
<p>If similar experiences in extreme events occur for the next 10 years – which is not a bad assumption given that four of the most expensive years in history <a href="https://www.ncei.noaa.gov/news/national-climate-201812">have occurred in the last five</a> – U.S. GDP in 2029 would be about 3.6% lower than it would have been otherwise, based on my calculations using growth accounting. </p>
<p>That amounts to an economy that’s $1 trillion poorer as result of these extreme weather events crowding out productive investment.</p>
<p>This is the real cost of a world in which these types of massively destructive disasters happen more frequently. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/290753/original/file-20190903-175686-l8vwid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290753/original/file-20190903-175686-l8vwid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290753/original/file-20190903-175686-l8vwid.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290753/original/file-20190903-175686-l8vwid.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290753/original/file-20190903-175686-l8vwid.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290753/original/file-20190903-175686-l8vwid.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290753/original/file-20190903-175686-l8vwid.jpg?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">
<figcaption>
<span class="caption">Climate change costs may be unfathomable by the end of the century.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Polar-Bear-Weight-Loss/c6edeba474164dc893b00c0263f13264/29/0">AP Images/Brian Battaile</a></span>
</figcaption>
</figure>
<h2>Sooner and scarier</h2>
<p>Returning to our 10% figure, 3.6% is comparatively smaller, of course, but it’s much sooner, which makes it much scarier. </p>
<p>Why?</p>
<p>Because the number of extreme events and their destructive power keeps <a href="https://public.wmo.int/en/media/press-release/state-of-climate-2018-shows-accelerating-climate-change-impacts">increasing at an accelerating rate</a>. If we can expect to take a $1 trillion hit over just the next decade, the costs by the end of the century are hardly fathomable.</p>
<p>So while I may disagree with the numbers The New York Times and others use in tallying disasters, they are right to try to spur readers to action. </p>
<p>The situation is just a lot more dire then anyone realizes. With any luck, the size of the figure will frighten us to do more to stave off the worst. </p>
<p><em>This is an updated version of an <a href="https://theconversation.com/drafts/108315/edit">article originally published</a> on May 31, 2019.</em></p><img src="https://counter.theconversation.com/content/122910/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gary W. Yohe 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>The usual way we calculate the economic damage of natural disasters underestimates their true toll – which is key to understanding the costs of climate change.Gary W. Yohe, Huffington Foundation Professor of Economics and Environmental Studies, Wesleyan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1083152019-05-31T20:59:30Z2019-05-31T20:59:30ZThe economic cost of devastating hurricanes and other extreme weather events is even worse than we thought<p>June marks the official start of hurricane season. If recent history is any guide, it will prove to be another destructive year thanks to the worsening impact of climate change. </p>
<p>But beyond more intense hurricanes and explosive wildfires, the warming climate <a href="https://www.huffingtonpost.com/entry/opinion-climate-change-deaths_us_5c101e14e4b0ac5371799b1c">has been blamed</a> for <a href="https://www.ncbi.nlm.nih.gov/pubmed/28663496">causing a sharp uptick</a> in all types of extreme weather events across the country, such as <a href="https://earther.gizmodo.com/this-springs-flooding-crisis-is-part-of-a-bigger-patter-1835092237">severe flooding across the U.S.</a> this spring and <a href="https://www.climate.gov/USdrought2018">extensive drought</a> in the Southwest in recent years.</p>
<p>Late last year, the <a href="https://www.cnn.com/2018/11/23/health/climate-change-report-bn/index.html">media blared</a> that these and other consequences of climate change <a href="https://www.vox.com/2018/11/24/18109883/climate-report-2018-national-assessment">could cut U.S. GDP</a> by 10% by the end of the century – “more than double the losses of the Great Depression,” as <a href="https://www.nytimes.com/2018/11/23/climate/us-climate-report.html">The New York Times intoned</a>. That figure was drawn from a single figure in the U.S. government’s <a href="https://nca2018.globalchange.gov">Fourth National Climate Assessment</a>. (Disclosure: I reviewed that report and was the vice chair on the third one, released in 2014.)</p>
<p>If that sounds scary, I have good news and bad news. The good news is that that figure was drawn incorrectly from a significant misreading of the report - which actually offered a range of a loss of GDP from as low as 6% to as high as 14% by 2090.</p>
<p>The bad news, however, is that a more meaningful assessment of the costs of climate change – using basic economic principles <a href="https://gyohe.faculty.wesleyan.edu">I teach to undergrads</a> – is a hell of a lot scarier.</p>
<h2>Tallying the costs</h2>
<p>First, let’s look at how government agencies, insurance companies and the media calculate and report on the economic costs of disasters. </p>
<p>According to the National Oceanic and Atmospheric Administration, in 2018 hurricanes Michael and Florence each caused about US$25 billion in damages, <a href="https://www.noaa.gov/news/2018-was-4th-hottest-year-on-record-for-globe">contributing to a total toll of $91 billion</a> from that year’s weather and climate disasters. In 2017, the NOAA’s total was even bigger: $306 billion, <a href="https://www.climate.gov/news-features/blogs/beyond-data/2017-us-billion-dollar-weather-and-climate-disasters-historic-year">due to the massive destruction</a> from hurricanes Harvey, Irma and Maria. </p>
<p>But these tallies are not really valid measures of economic damage. Instead, they simply reflect estimates of what people think will need to be invested to rebuild what was damaged or destroyed in the storms, floods or fires.</p>
<p>To really understand the economic costs of an extreme weather event, it’s important to consider all the investment that is being “crowded out” or lost to cover those rebuilding costs. Put another way, there’s only so much money to go around. And that $25 billion being used to rebuild means $25 billion is not being used for other public and private investment opportunities that are more forward-looking or more likely to promote growth.</p>
<h2>Accounting for growth</h2>
<p>Instead, I believe a fundamentally more sound way to do this is to use something called “growth accounting.”</p>
<p><a href="https://economics.mit.edu/files/7183">Growth accounting</a> incorporates the productive use of capital and innovation into the equation. The question we want to ask is what happens to GDP growth when recovery efforts from extreme events crowd out productive investments, like building new factories or roads and bridges? </p>
<p>Returning to NOAA’s estimated losses for 2017 and 2018, productive investment fell about $400 billion in total in those years as a result. That is, had those disasters not happened, investment would have been that much higher. And that diminished investment translates into less growth in gross domestic product – a measure of all an economy produces in a given period.</p>
<p>If similar experiences in extreme events occur for the next 10 years – which is not a bad assumption given that four of the most expensive years in history <a href="https://www.ncei.noaa.gov/news/national-climate-201812">have occurred in the last five</a> – U.S. GDP in 2029 would be about 3.6% lower than it would have been otherwise, based on my calculations using growth accounting. </p>
<p>That amounts to an economy that’s $1 trillion poorer as result of these extreme weather events crowding out productive investment.</p>
<p>This is the real cost of a world in which these types of massively destructive disasters happen more frequently. </p>
<h2>Sooner and scarier</h2>
<p>Returning to our 10% figure, 3.6% is comparatively smaller, of course, but it’s much sooner, which makes it much scarier. </p>
<p>Why?</p>
<p>Because the number of extreme events and their destructive power keeps <a href="https://public.wmo.int/en/media/press-release/state-of-climate-2018-shows-accelerating-climate-change-impacts">increasing at an accelerating rate</a>. If we can expect to take a $1 trillion hit over just the next decade, the costs by the end of the century are hardly fathomable.</p>
<p>So while I may disagree with the numbers The New York Times and others use in tallying disasters, they are right to try to spur readers to action. </p>
<p>The situation is just a lot more dire then anyone realizes. With any luck, the size of the figure will frighten us to do more to stave off the worst.</p><img src="https://counter.theconversation.com/content/108315/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gary W. Yohe was Vice Chair of the Third National Climate Assessment (2014) and reviewer of the Fourth. He is Co-editor-Chief of Climatic Change, a member of the New York City Panel on Climate Change, and long term senior member of the Intergovernmental Panel on Climate Change. </span></em></p>With hurricane season comes the usual efforts by insurance companies and government agencies to calculate the economic costs. An economist explains how they’re doing it wrong.Gary W. Yohe, Huffington Foundation Professor of Economics and Environmental Studies, Wesleyan UniversityLicensed as Creative Commons – attribution, no derivatives.