Research suggests urban sprawl, wet falls and winters influence severe weather
Previously rare big city storms like a 2009 tornado that downed trees and ripped off roofs in downtown Minneapolis and a 2008 twister in Atlanta that killed one person and caused $250 million damage may not be so unusual anymore.
As large urban areas like Minneapolis, Atlanta, St. Louis and Indianapolis continue to expand, they appear to influence tornadoes and other severe weather, research by Purdue Professor Dev Niyogi suggests. Cities could be even more at risk if located in a region experiencing a wet fall or winter, according to research from Purdue and the University of Georgia.
One study by Niyogi and Professor Marshall Shepherd at Georgia found that drought in the fall and winter appears to decrease the number of spring and summer tornadoes in the U.S. Southeast. Wet falls and winters, on the other hand, may increase tornado activity, with nearly twice as many recorded.
In studying the Atlanta tornado, Niyogi and Shepherd employed cutting-edge satellite data from NASA and the Japanese space agency to model the storm in reverse on supercomputers from ITaP and the National Center for Atmospheric Research. They found that a storm already fueled by drought areas moistened in a recent rain shower may have been further energized by the urban landscape with its heat-retaining effects and rough surface, which pinpointed the storm’s worst moments over the city.
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