Tornadoes

Tornadoes, microbursts, and silver linings

Bob Henson • April 1, 2014 | It takes a sharp eye to find something positive in the wreckage of the worst swarm of U.S. tornadoes on record. Ted Fujita had just such an eye, and millions of Americans are safer in the air because of it. Theodore "Ted" Fujita was renowned for his meticulous work in observing and analyzing meteorological phenomena, including tornadoes and microbursts, through photographs and damage surveys as well as weather data. (Photo courtesy University of Chicago.) Fujita, who died in 1998, is known around the world for devising the Fujita Tornado Damage Scale, or F-scale. Now reworked as the Enhanced Fujita Tornado Damage Scale, it’s the system most commonly used to rank tornado strength based on observed damage. A prolific researcher, Fujita made many other contributions to meteorology that are less well known to the public. One standout is his conceptualization of microbursts, the small yet dangerous pockets of descending wind that even weak showers can produce. Fujita and colleagues at the University of Chicago joined with NCAR researchers in the late 1970s and 1980s in definitive work that clarified the danger posed to aviation by microbursts. The effort was a spectacular success—and it all started in the wake of a devastating round of tornadoes that struck 40 years ago this week. Insight from tragedy On April 3, 1974, the U.S. South and Midwest were raked by more than 140 tornadoes that killed more than 300 people. The sheer scope of this disaster, which Fujita dubbed the Jumbo Outbreak (it’s also referred to as the Super Outbreak), went beyond anything previously measured. Since then, the only comparable event was the rash of more than 300 tornadoes across much of the eastern United States on April 25–28, 2011, again killing more than 300 people. While conducting an aerial survey of damage from the Jumbo Outbreak, Fujita—already known among peers as a meticulous observer—noticed something strange. He recounted the experience in a 1985 monograph, The Microburst: The deadliest single tornado of the Jumbo Outbreak on April 3, 1974, plowed through Xenia, Ohio, killing 36 people. (Wikimedia Commons image.) “Unlike the swirling patterns of fallen trees, commonly seen from the air in the wake of tornadoes, hundreds of trees were blown outward in a starburst pattern. Trees near the starburst center were flattened or uprooted, spattered by a brownish topsoil.” Fujita reasoned that such damage was produced not by the inflowing, rising air in a tornado, but rather from a focused surge of descending air that suddenly diverges when it hits the ground. He likened this to flow from a garden hose. If the hose is pointed directly downward, the water will spray outward in all directions, but if the hose is angled just slightly, the water fans out toward one side, much like the damage observed by Fujita. Fujita concluded that about 15 percent of the jaw-dropping 2,598 linear miles of damage he mapped from the Super Outbreak was caused by these “outburst” winds, rather than by tornadoes. The next critical event occurred on the stormy day of June 24, 1975, when an Eastern Airlines plane crashed on approach at New York’s Kennedy International Airport, killing 113 people. Analyzing eyewitness reports and black-box data, and recalling the damage patterns he’d observed the year before, Fujita concluded that a “downburst” was likely responsible for the crash. (He later coined the term “microburst” to describe a downburst that was no more than 2.5 miles wide at ground level. See this comparison.) Quelling the critics with field data As with many transformative scientific ideas, Fujita’s concept came up against prominent detractors. Most researchers at the time believed that even strong downdrafts from thunderstorms ought to weaken before reaching the surface. Fujita also bucked convention in how he carried out his research. “The large majority of his downburst work was not published in peer-reviewed journals,” noted Jim Wilson (NCAR) and Roger Wakimoto (now NSF assistant director for the Directorate for Geosciences) in a 2001 retrospective for the Bulletin of the American Meteorological Society (see PDF). They wrote: “It is likely that [the publication process] would have been an irritating, time-consuming activity for Fujita. He probably realized reviewers would have questioned his unorthodox analysis procedures and heavy use of unstated assumptions.” As Fujita continued to gather data through aerial damage surveys in the late 1970s, he also enlisted the help of NCAR and its pair of portable Doppler radars, which were then among only a handful available in the world available for atmospheric research. With encouragement from Bob Serafin, who managed NCAR’s observing facilities at the time (and who later became NCAR director), NSF agreed to fund a field campaign. “At a time when many in the scientific community had serious doubts about Fujita’s downburst hypothesis, these two [entities (NSF and NCAR)] fully supported his efforts,” noted Wilson and Wakimoto. Several landmark field projects over the next decade made it clear that Fujita was on the right track. Descending air curls outward and upward as it slams into the ground in a microburst near Denver's former Stapleton International Airport on July 6, 1984, during the CLAWS project (Classify, Locate, Avoid Wind Shear). (Photo by Wendy Schreiber-Abshire, ©UCAR. This image is freely available for media & nonprofit use.) NIMROD, the Northern Illinois Meteorological Research on Downbursts, combined NCAR’s two radars with the CHILL radar (University of Chicago/Illinois State Water Survey). As NIMROD detected its first microburst, on May 29, 1978, Fujita and Wilson stepped outside and were almost blown into a nearby farm pond.  The radars and surface stations ended up detecting about 50 microbursts that spring and summer. JAWS, the Joint Airport Wind Shear project, took place in northeast Colorado in 1982, followed by CLAWS (Classify, Locate, and Avoid Wind Shear) in 1984. With three NCAR Doppler radars positioned more closely together, Fujita identified more than 180 microbursts and analyzed several in great detail through vertical cross sections. One of the stronger microbursts occurred near Denver’s former Stapleton Airport from a cloud with a radar reflectivity of just 17 dBZ—barely a detectable shower. (Fujita also saw his first-ever tornado that summer, near the town of Bennett.) MIST, the Microburst and Severe Thunderstorm project, brought the three NCAR Doppler radars to northern Alabama in 1986. This study focused on “wet” microbursts—those fed by great volumes of heavy rain, as opposed to the evaporation and cooling that produced the “dry” microbursts common in more arid regimes.   NCAR’s John McCarthy spent much of his time during the summers of 1984 and 1985 in the control tower of Denver’s Stapleton International Airport during the CLAWS project. (©UCAR. This image is freely available for media & nonprofit use.) Results from these field projects quickly convinced skeptics that microbursts were a bona fide threat to aviation. This initial awareness helped pilots and air traffic controllers stem the rate of major microburst-related accidents, which had been occurring every year or two in the 1970s and early 1980s. More intensive pilot training, much of it initiated by NCAR’s John McCarthy and sponsored by the Federal Aviation Administration, cemented the new concepts. Technology also made a huge difference. Building on research led by McCarthy, and with FAA support, NCAR teamed up with the Massachusetts Institute of Technology’s Lincoln Laboratory to develop software that generated wind-shear alerts, drawing on observations from surface weather stations near airports and a new network of airport-based Doppler radars. As the new tools and observing systems spread nationwide, microburst-related accidents became increasingly rare: the last major U.S. flight mishap attributed to wind shear occurred in 1995. RAL is still actively helping international governments and airport authorities procure wind shear systems. “The microburst/aircraft problem demonstrated how funding focused on a particular weather problem can lead to an operational solution,” says Wilson. The next challenges It’s likely that hundreds of deaths have been avoided thanks to Ted Fujita’s uncommon insight, his exhaustive documentation, and the careful field work carried out by NCAR scientists and their collaborators. Many of them remain active in research, savoring the microburst success even as they look to new areas where knowledge and technology can make transportation safer and more efficient. Much of this work now takes place within the framework of the FAA’s NextGen initiative, a comprehensive approach to aircraft navigation, weather information, and safety. Turbulence remains a vexing aviation problem. Even with no thunderstorms nearby, severe turbulence injured 11 people (two seriously) in February aboard a United Airlines flight en route from Denver to Billings, Montana. To date, around 200 United and Delta aircraft have tested an NCAR-developed system that automatically diagnoses turbulence and creates global maps of turbulence intensity. Southwest Airlines is expected to join the system later this year. Another NCAR software package uses Doppler radar data to remotely detect turbulence related to thunderstorms. Icing is another long-recognized hazard that’s being partially tamed by technology. An NCAR-developed system, now marketed by Vaisala, allows airports to monitor snowfall rate and other weather factors crucial to aircraft de-icing as they unfold. Two products developed at NCAR use current observations and short-range computer models to map out where in-flight icing conditions are expected to be most likely and most severe, both now and over the next 12 hours. NCAR is also collaborating with NOAA on a prototype system that would provide a global picture of predicted icing severity. This graphic display from the FIP-Severity software program depicts a two-hour icing severity forecast across the United States on March 15, 2011. The forecast is for a column extending from 1,000 to 30,000 feet above mean sea level. The shades of blue denote the level of severity, with dark blue indicating heavy icing. The red areas of "SLD threat" are warnings for the presence of supercooled large drops, an indicator of severe icing potential. Icing can create a significant hazard for some types of aircraft. (Image courtesy NOAA/NWS/ADDS.) Even though U.S. air travel is safer than ever, passengers can still encounter major inconvenience with long delays and cancelled flights. A new NCAR-based tool for air traffic awareness could help give airlines a probabilistic sense of where, when, and how many flights are likely to be hindered by thunderstorms. The system converts output from high-resolution computer forecast models into estimates of how much airspace capacity might be reduced—essentially switching the forecast product from weather itself to its impact on flights. The time frame of several hours into the future represents a sweet spot, with the probabilistic approach allowing for guidance beyond “nowcasting” of thunderstorms and other threats while giving traffic controllers and airlines a valuable planning window. The experimental project has been funded by NASA, the FAA, and most recently the National Weather Service. It’s also possible that some of the next transformative breakthroughs in transportation safety will occur on terra firma. Weather-related highway accidents kill thousands of Americans each year. NCAR’s Research Applications Laboratory—which emerged after the successful attack on the microburst problem—now includes a branch focused on surface transportation. Among their current projects is a winter-weather decision support system that uses weather and road data sent by specially equipped snowplows to help determine where plowing and sanding are most needed. When deployed on a larger scale, millions of “intelligent” vehicles might someday give drivers crucial advance notice of ice, rain, and other potential road hazards just around the bend.  As with microbursts and aircraft, there’s nothing like the power of plentiful data and thorough analyses to help keep people safe from weather’s worst.

Modeling study captures deadly tornado outbreak

October 26, 2011 | NCAR scientists have performed one of the most detailed simulations ever of a massive tornado outbreak. In late April 2011, an extremely violent spate of tornadoes, dubbed the Super Outbreak, tore a path of destruction through the southern and eastern parts of the United States, making April 27 the deadliest U.S. tornado day since 1925. Especially hard hit was Alabama, where a series of supercell storms and accompanying tornadoes resulted in 239 deaths. The research team, led by Wanli Wu and Yubao Liu, used an advanced weather forecasting system built on the NCAR-based Weather Research and Forecasting model. They simulated two waves of tornadic storms that occurred on April 27 in Alabama. The experiment tested the model’s ability for fine-resolution precision forecasting. The model successfully captured the severe storm system that moved through the study area, the supercell vortices that spun off some of the tornadoes, and the waves of tornado-like damaging winds. Whereas many past tornado studies have targeted individual tornadoes, this one simulated the widespread, massive collection of tornadoes observed in both the morning and evening hours. Although predicting the precise timing and locations of individual tornadoes remains a challenge, the model’s fine resolution of 300 meters (328 yards) captured many tornadogenesis processes and features, such as strong updrafts and downdrafts, along with the overall storm system.

Tornado researchers catch a squall line during VORTEX2

June 17, 2010 | In the spring of 2009, researchers on the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) field project set out across the Great Plains to study tornadoes, but that’s not the only phenomenon they observed. They also got an exceptionally close look at a squall line, or line of severe thunderstorms that forms along or ahead of cold fronts, producing severe weather in the form of heavy rainfall, strong winds, hail, and lightning. The analysis, led by NCAR scientist George Bryan, will be published in Monthly Weather Review. In recent decades, scientists have learned much about squall line dynamics through Doppler radar data and numerical simulations, but in situ (in place) observations of temperature and moisture in squall lines have been rare. Networks of operational rawinsondes (radiosondes designed to measure wind speed and direction) are too coarse to capture the structure of squall lines, and airplane flights in these regions are too hazardous. During VORTEX2, the research team used high-frequency rawinsonde launches from ground-based mobile platforms to observe a squall line that passed near the project’s armada of mobile observing facilities in Oklahoma on May 15. Nine soundings were taken over a three-hour period, allowing for an unprecedented view of the squall line’s internal structure and nearby environment. The observational data retrieved during this unique event confirms much of what scientists know about squall lines from numerical modeling. The team was surprised to find, however, that the squall line’s cold pool (relatively cold air found near the surface after the gust front passed but before precipitation began) was 4 kilometers (2.5 miles) deep—several times deeper than previous research on squall lines has indicated for cold pools. Because this was the only squall line observed during VORTEX2’s 2009 phase, researchers stress the need for future field observations on squall lines. The research has the potential to help scientists confirm and improve weather forecasts and is also applicable to climate simulations.

Scrutinizing the Windsor twister from all angles

May 12, 2010 | After a very unusual tornado caused extensive damage along a 34-mile (55-kilometer) swath of northern Colorado in 2008, a team of scientists from NCAR and Colorado State University undertook a multidisciplinary study integrating meteorology, climatology, and social science. The study, published in Weather and Forecasting, dissects the May 22 tornado near the town of Windsor from a meteorological perspective, places it in a climatological context, and analyzes how severe weather information was communicated to and interpreted by decision makers and then passed on to the public.   The Windsor tornado, which caused one death and ranks as the costliest tornado in Colorado’s history at $193.5 million in damages, was rated EF3 on the Enhanced Fujita scale. Several characteristics of the tornado were unique for the region. The storm formed in the late morning, in contrast to the usual pattern of afternoon storms. It moved toward the north/northwest (toward population centers) rather than along the more common eastward storm track. It was strong and long-lived for a tornado close to the Front Range, where weaker tornadoes are more common. The unusual characteristics and rapid development of the tornado created a complex situation for decision makers, whose interpretations of warning information varied widely. For example, since most decision makers knew that tornadoes in the area typically move eastward, some downplayed the possibility that the tornado would move toward them, despite the fact that they were in the tornado’s path. Many decision makers were surprised that such a strong tornado could occur in their area. Although none had been reported in the preceding 50 years, the study pointed out that the area near Windsor had been hit by strong tornadoes several times in the early 20th century.    The research underscores the growing recognition that societal factors are just as important for the effectiveness of weather warnings as the timeliness and content of those warnings. “To achieve the goal of better tornado warnings, we need to not only improve detection and prediction of tornadoes, but also understand how people receive, understand, and use warnings, so that the information that meteorologists have can be best communicated to decision makers and the public,” says author Russ Schumacher, a professor at Texas A&M who undertook the study while a postdoctoral researcher at NCAR.

Scientists to track twisters in world’s largest tornado study

BOULDER—More than 100 researchers will begin deploying a flotilla of instruments across the Great Plains next week, aiming to surround tornadoes with an unprecedented fleet of mobile radars and other cutting-edge instruments in the second and final year of the most ambitious tornado study in history. NCAR scientists and technicians will launch weather balloons at VORTEX2 with their Mobile GPS Advanced Upper-Air Sounding System. Shown here are (left to right) William Brown, Jennifer Standridge, and Tim Lim testing a balloon launch (©UCAR, Photo by Carlye Calvin.) News media terms of use* The collaborative international project, involving scientists from the National Center for Atmospheric Research (NCAR) and a number of other organizations, examines in detail how tornadoes form and the patterns of damage they cause. The findings are leading to a greater understanding of tornadoes, and scientists expect they will ultimately improve tornado warnings and short-term severe weather forecasts. The field campaign, known as VORTEX2 (Verification of the Origins of Rotation in Tornadoes Experiment 2), runs from May 1 to June 15. It covers the most active part of tornado season on the Great Plains, where violent twisters are more common than any other place in the world. “Tornadoes rank among the most destructive weather events on Earth, and it’s imperative that we learn more about how they develop and why some are so powerful  and long-lived,” says David Dowell, an NCAR scientist who is a principal investigator on the project. “We’re hoping to improve the lead time and accuracy for tornado warnings. If we can understand these forces better, that could ultimately save lives.” During the first phase of VORTEX2 last spring, researchers made key observations of a tornado in southeast Wyoming that was rated EF2 on the Enhanced Fujita tornado damage scale. They also collected data on several powerful nontornadic storms. Such information will help researchers distinguish between thunderstorms that produce tornadoes and those that do not. This year’s study period is about two weeks longer than last year’s, which enhances the odds of tracking down tornadoes. The $11.9 million VORTEX2 program is funded primarily by the National Science Foundation, which sponsors NCAR, and by the National Oceanic and Atmospheric Administration (NOAA). In addition to NCAR, participants include the Center for Severe Weather Research, Rasmussen Systems, NOAA National Severe Storms Laboratory, NOAA Cooperative Institute for Mesoscale Meteorological Studies at the University of Oklahoma, Pennsylvania State University, Texas Tech University, Lyndon State College, Purdue University, North Carolina State University, the universities of Oklahoma, Colorado, Massachusetts, and Nebraska, Environment Canada, and the Australian Bureau of Meteorology. Targeting the zone where tornadoes spawn The first VORTEX project, conducted in 1994 and 1995, gathered critical data on supercells, the severe and long-lived thunderstorms that give birth to the most destructive and deadly tornadoes. VORTEX findings are credited with improving National Weather Service tornado warnings. Building on that progress, VORTEX2 researchers are using an armada of enhanced mobile radars and other new weather-sensing tools to gather far more detail on the crucial zone where tornadoes develop. Rapidly changing contrasts in wind and temperature in this zone, which is only a few miles across, can spawn a tornado within minutes. However, this happens in only a small fraction of supercell storms, and standard observing networks and radars often fail to capture the atmospheric conditions that lead to a tornado. Among the key questions that VORTEX2 researchers want to answer: How do tornadoes form? Why do some supercell thunderstorms spawn tornadoes, while others do not? Why are some tornadoes violent and long-lasting while others are weak and short-lived? How much detail can we see inside a tornado? How strong are winds near the ground? How do they cause damage? Can forecasts be improved? Current warnings have a 13-minute average lead time and a 70 percent false alarm rate. Is it possible to improve forecast accuracy and warn residents a half hour or more in advance? To capitalize on the unusual mass of mobile instruments, researchers will also look for opportunities to collect data on other major weather events in the region. A team of VORTEX2 scientists last year, for example, made unusually detailed observations of squall lines, which can produce damaging hail and lightning, and sometimes tornadoes as well. “We have a vast collection of tools that can give us unique insights into the atmosphere,” says George Bryan, an NCAR scientist and VORTEX2 principal investigator. "So we try to get the most out of them that we can." Mega-fleet targets tornadoes The VORTEX2 study area (left), shown as a red loop, stretches some 900 miles from north to south across the Great Plains. Shown at right is a supercell thunderstorm surrounded by VORTEX2 observing teams. The heaviest precipitation, in green, loops around the target area where a tornado might occur. (Image courtesy VORTEX2.) News media terms of use* The radar fleet for VORTEX2, including 10 mobile radars, will track winds and precipitation in and near tornadoes in unprecedented detail. The instruments will have a resolution as fine as 100 feet and time steps as small as 10 seconds. More than three dozen portable surface weather stations can blanket the area in and near a target storm.  A robotic 12-foot propeller aircraft will probe the edges of severe storms. The study area spans more than 900 miles, stretching from West Texas to southwestern Minnesota. On each day of operations, VORTEX2 teams will position equipment about an hour ahead of a potentially tornadic storm and remain in place until the storm passes. With no home base, the scientists remain on the road during the entire six-week study. Meteorologists will provide detailed forecasts on short-fuse weather events as each day unfolds, using tools such as the Weather Research and Forecasting computer model, which proved its value during the 2009 campaign. WRF, pronounced "worf," was developed by NOAA, NCAR, and partners. About half of the participants in the field will be undergraduate and graduate students. This is an unusually high percentage for a major field campaign and will provide a special learning experience for young researchers.

World's Largest Tornado Experiment Heads for Great Plains

  News Release Multimedia Gallery   BOULDER—The largest and most ambitious tornado study in history will begin next week, as dozens of scientists deploy radars and other ground-based instruments across the Great Plains to gain a better understanding of these often deadly weather events. NCAR scientists and technicians will launch weather balloons at VORTEX2 with their Mobile GPS Advanced Upper-Air Sounding System. Shown here are (left to right) William Brown, Jennifer Standridge, and Tim Lim testing a balloon launch [ENLARGE] (Photo by Carlye Calvin.) News media terms of use* The collaborative international project, involving scientists from the National Center for Atmospheric Research (NCAR) and a number of other organizations, will examine in detail how tornadoes form and the patterns of damage they cause. The findings are expected to improve tornado warnings and short-term severe weather forecasts. The field campaign, known as VORTEX2 (Verification of the Origins of Rotation in Tornadoes EXperiment 2), will run from May 10 to June 13. A second phase is planned for the spring of 2010. "We still do not completely understand the processes that lead to tornado formation and shape its development," says Roger Wakimoto, director of NCAR's Earth Observing Laboratory and a principal investigator for VORTEX2. "We hope that VORTEX2 will provide the data we need to learn more about the development of tornadoes and in time help forecasters give people more advance warning before a tornado strikes." The $11.9 million VORTEX2 program is funded primarily by the National Science Foundation, which sponsors NCAR, and by the National Oceanic and Atmospheric Administration. In addition to NCAR, participants include the Center for Severe Weather Research, Rasmussen Systems, NOAA National Severe Storms Laboratory, NOAA Cooperative Institute for Mesoscale Meteorological Studies at the University of Oklahoma, Pennsylvania State University, University of Oklahoma, Texas Tech University, Lyndon State College, University of Colorado, Purdue University, North Carolina State University, University of Illinois, University of Massachusetts, University of Nebraska, Environment Canada, and the Australian Bureau of Meteorology. NCAR's Roger Wakimoto, a principal investigator for VORTEX2, explains some of the science behind the field project. He will be using video and damage surveys to analyze the structure of tornadoes. This one-minute animation (QuickTime) gives a 3-D overview of the VORTEX fleet, with descriptions of instruments as they might be deployed around a potentially tornadic thunderstorm. The crucial zone The first VORTEX project, conducted in 1994 and 1995, gathered critical data on supercells, the severe and long-lived thunderstorms that give birth to the most destructive and deadly tornadoes. VORTEX findings are credited for improving National Weather Service tornado warnings, which now have a lead time of about 13 minutes. Building on that progress, VORTEX2 researchers will use enhanced mobile radars and other new weather-sensing tools to gather far more detail on the crucial zone where tornadoes develop. Rapidly changing contrasts in wind and temperature in this zone, which is only a few miles across, can spawn a tornado within minutes. However, such an event happens in only a small fraction of supercell storms, and standard observing networks and radars often fail to capture the atmospheric conditions that lead to a tornado. "VORTEX2 will help us better understand the difference between thunderstorms that produce tornadoes and those that don't," says NCAR scientist David Dowell, a VORTEX2 field coordinator. "By identifying the characteristics of severe thunderstorms that produce tornadoes, forecasters will be able to issue tornado warnings further in advance and potentially save lives." Probing a vast region with high-tech tools A high-resolution version of this animation (1920 x 1080 pixels) suitable for HD broadcast can be downloaded via FTP at ftp://ftp.ucar.edu/communications/vortex_2_HD.mov. This version of the animation omits the text that details each type of instrument. The radar fleet for VORTEX2, including 10 mobile radars, will track winds and precipitation in and near tornadoes in unprecedented detail. The instruments will have a resolution as fine as 300 feet and time steps as small as 15 seconds. More than three dozen portable surface weather stations will blanket the area in and near a target storm. The VORTEX2 study area spans more than 900 miles, stretching from west Texas to southwest Minnesota. On each day of operations, participants will position equipment about an hour ahead of a potentially tornadic storm and remain in place until the storm arrives. NOAA forecasters and partners will provide intensive guidance on short-fuse weather events as each day unfolds. The VORTEX2 study area (left), shown as a red loop, stretches some 900 miles from north to south across the Great Plains. Shown at right is a supercell thunderstorm surrounded by VORTEX2 observing teams. The heaviest precipitation, in green, loops around the target area where a tornado might occur. (Image courtesy VORTEX2.) News media terms of use*

Tornado warnings and public response

April 6, 2009 | The 2008 Super Tuesday tornado outbreak—so named because it began on Tuesday, February 5, when 24 states were holding primary elections and caucuses—swept through several southern states and the lower Ohio Valley, killing 57 people. NCAR scientist Julie Demuth helped the National Weather Service assess the societal impacts of the deadly tornadoes. The NWS undertakes these “service assessments” after major weather events, seeking input from government agencies, emergency managers, the media, and the public. Julie served as the societal impacts representative on a team of 11 contributors, including nine NWS employees and an emergency manager from Kansas. In the weeks following the tornado outbreak, the team went into the field, where Julie conducted in-person and phone interviews with the public. The objective was to discover as much as possible about the 57 fatalities and to interview survivors to assess their knowledge, perceptions, and decision making regarding the event. NOAA released a report on March 9, 2009, based on the team’s findings and recommendations. “Service Assessment of the Super Tuesday Tornado Outbreak of February 5-6, 2008,” analyzes forecasting performance and public response during the event and addresses a key area of concern: better understanding of people’s behavior when warnings are issued during severe weather events. The assessment team found that most people were aware of the dangerous weather threat and received warnings of the tornadoes. For many people, a single source of information did not spur them to take protective action; rather, they used multiple sources to assess their personal risks. Although most people who received warnings did ultimately take cover in the best locations available to them, lack of adequate shelter was a problem as the majority of the survivors did not have access to safe ones (basements, storm cellars, or safe rooms) and two-thirds of the victims were in mobile homes.   For more details, click here.
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