When many people think of tornado outbreaks, states like Oklahoma, Kansas and Nebraska come to mind. Although tornadoes touch down in many places across the eastern half of the country, from the 1950s through the 1990s they struck most often in Tornado Alley, an oval area centered on northeastern Texas and south-central Oklahoma. More recently, that focus has shifted eastward by 400 to 500 miles. In the past decade or so tornadoes have become prevalent in eastern Missouri and Arkansas, western Tennessee and Kentucky, and northern Mississippi and Alabama — a new region of concentrated storms. Why is this shift happening now? Climate change is warming the Gulf of Mexico, which can send generous amounts of water vapor into the southeastern United States. Tornado Alley moving eastward is more than a meteorological curiosity — the shift is serious. Tornado shelters are common in Texas and Oklahoma but less so elsewhere. The Southeast is more densely populated, and mobile homes, which fare poorly in windstorms, are much more common. Tornadoes in the Southeast also occur at night more often than they do farther west, in part because winds can bring ample moisture from the Gulf after dark. Studies show that tornadoes that strike at night are twice as likely to cause fatalities. Local and state governments in the new bullseye region might want to improve community shelters and warning systems, strengthen building codes, better equip emergency responders, and educate residents about what to do and not to do if a tornado is headed their way.
