Discover the anatomy of a tornado
• The last two tornado seasons have been the deadliest in a decade, with 206 deaths. Everyone from the insurance industry to Al Gore worries thatglobal warming may be causing more tornado activity. But there's no baseline for comparison. That's because we have no accurate record of tornadoes before the 1950s, back when it was possible for thesebrief, freakish funnels of air to blow over then-unpopulated areas without notice.
• Tornado warnings have improved over the years; forecasters can now issue warnings about 18 minutes beforetouchdown for 75 percent of twisters. As for longer-term forecasts, the science isn't there yet, despite what you hear on the nightly news. "Television forecasters pander to the public's curiosity aboutextreme weather," says Michael H. Glantz, a professor at the University of Colorado at Boulder. Their goal, of course, is to be first with a forecast of trouble ahead. But beware those who insist onlinking El Niño (the cyclical surface warming of the eastern Pacific Ocean) to tornado likelihood. The slight correlation is "not enough to be directly useful in forecasting," says Joe Schaefer, directorof the Storm Prediction Center in Norman, Oklahoma.
• The number of deaths per tornado is greater in the South than in Tornado Alley (the Great Plains and part of the Midwest)—a disparity thatcan't be explained by storm frequency or severity. Experts say things like terrain, population density, and the number of mobile homes play a role. But the biggest factor might be timing: "In the Plains,"explains Schaefer, "we have a much more clearly defined period of tornado activity, generally from March to late June. In the Southeast, tornadoes can happen all year long, so there may be lessvigilance." Research also shows that the South may have a climatological propensity for nighttime storms, which catch people unawares—asleep in bed. Last year's two killer tornado outbreaks in North...
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