ScienceShot: Twisters Spread Out

Tornado Alley just got bigger. A swath of the Great Plains between west Texas and Minnesota, the loosely defined region gets its nickname from the substantial amount of tornado activity that occurs there. But now researchers have found that many locales in Dixie are more twister-prone than Kansas. By tallying tornado occurrence for each square kilometer of the lower 48 states from 1950 through 2007, the team identified sites in large patches of south-central Mississippi and central Arkansas that have tornadoes pass within 25 miles of them at least once each year (as depicted in the orange and deep red areas of the map above). Such rates are similar to those seen in tornado hotspots of the Great Plains. Sites in Smith County, Mississippi, historically the most twister-afflicted area of the nation, had tornadoes pass close by about 35% more often than those in many areas traditionally considered the heart of Tornado Alley. In fact, large swaths from northern Louisiana to northern Alabama are just as likely to suffer twisters as the Great Plains, the researchers report in an upcoming issue of the Bulletin of the American Meteorological Society. Expanding the tornado risk map to include these areas will increase public awareness and boost efforts to mitigate damages from twisters, the team contends.

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