Carnegie Mellon University
October 26, 2020

Misperceptions about Southeast Tornado Risk

Researchers find people living in the southeastern United States lack knowledge of diffuse timing of these destructive storms, leaving residents vulnerable

By Stacy Kish

Tornadoes are spontaneous, destructive vortexes of air that descend to the Earth during particular atmospheric conditions. These storms leave a path of death and destruction that have prompted researchers to develop more accurate techniques to predict the impending risk to warn the public.

Unfortunately, tornadoes do not form under the same conditions throughout the country. The conditions that spawn these storms across the Great Plains are very different than the southeastern United States. A new study from Carnegie Mellon University has found most people are more familiar with the risk associated with Great Plains tornadoes, leaving residents in the southeastern United States vulnerable to increased storm risk. The research findings are available online in the September issue of the journal Weather, Climate, and Society.

“In the past, a big storm would come through [the Southeast] and cause destruction. There may have been a tornado that touched down but the storm was only documented as a severe thunderstorm,” said Stephen Broomell, associate professor in the Department of Social and Decisional Sciences at CMU. “If no one is there to see it and there is no evidence in the radar, there is no record of it happening. These days, people have cellphones and can take pictures, and we have higher resolution radar, so the number of small, weak tornadoes [in the Southeast] that can be verified is increasing.”

Along the Great Plains, tornadoes typically spawn from isolated supercell storms during the late spring and early summer. Conversely, tornadoes in the southeastern United States occur throughout the year with peak activity during the spring (March-May) and a secondary peak in the late fall and winter (November-February). In addition, the cold season tornadoes are more common at night, and tend to be less accurately predicted.

“The fact that people underestimate nocturnal tornado frequency will affect their decision making, like the type of home you live in,” said Broomell.

Higher tornado mortality in the Southeast may be related to differences in population density, housing characteristics and shelter options compared to the Great Plains, but public perception of tornado risk may also play a significant factor in the higher death toll in this region.

To shed greater light on this question, Broomell and his colleagues applied cognitive-ecological theory to evaluate how residents of the southeastern United States viewed tornado risk compared to their counterparts living along the Great Plains. The team surveyed meteorologists (50) as well as residents from the Southeast (1,050) and Great Plains (1,050) to obtain their understanding of tornado risk based on season, time of day and storm type.

The team found that that people living in the Southeast are more tuned to the risk conditions associated with Great Plains tornado conditions rather than their regional-specific conditions. This approach hinders residents in the Southeast because tornadoes are associated with a wider range of environmental conditions. In addition, people living in the southeastern United States may lack knowledge about the greater seasonality of tornadoes in the region. Southeast residents also identified the afternoon as the most common time for a tornado and lacked the knowledge of greater risk of nocturnal tornadoes during the winter months.

“The Great Plains tends to produce tornadoes that are big and visible. They really are textbook,” said Broomell. “Educating about tornadoes in the Southeast is more difficult because they are often obscured from vision and can occur at night. They just aren’t that straight forward.”

Broomell believes educational campaigns could fill this knowledge gap to inform residents of tornado seasonality, as well as how to interpret tornado forecasts and warnings to be better prepared and take protective actions.

“This work is a first step to understand the decision-making process for people in the Southeast to take shelter,” said Broomell. “Decision science can help us identify knowledge gaps so we can save lives.”

Broomell was joined by Gabrielle Wong-Parodi at Stanford University and Rebecca Morss and Julie Demuth at the National Center for Atmospheric Research in Boulder, Colo. on the project titled, “Do We Know Our Own Tornado Season? A Psychological Investigation of Perceived Tornado Likelihood in the Southeast U.S.” The project received financial support from National Oceanic and Atmospheric Administration and the National Science Foundation.