Science can’t design away tornadoes’ deadly threat

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Contributing to the massive loss of life is the growth of urban areas, suggested Marshall Shepherd, a professor of atmospheric science at the University of Georgia.

“Historically, the central business districts of cities have not been hit that frequently,” he explained. But as you increase the land area covered by homes and businesses, he said, “you’re increasing the size of the dartboard.”

An expanding population does increase exposure to the danger, agreed Ashley, who fears deaths could begin to rise in the future as a result of sprawl and more people living in vulnerable residences such as mobile homes.

If the Tuscaloosa and Joplin tornadoes had each been a few miles to the south, on farmland, little would be heard about them, Ashley said, but when extremely violent tornadoes mingle with urban sprawl “you’re going to have a disaster.”

“I hope this will be an outlier year, very much like Katrina was to hurricanes,” he said in a telephone interview from a field trip to chase tornadoes.

But no one can guarantee that, and weather experts are becoming increasingly concerned about how people respond to tornado warnings.

“A lot of it is complacency,” Ashley said. “The population seems to be becoming desensitized to nature. I don’t know why.”

Studies have shown that 15 to 20 minutes is the most effective amount of warning time, and longer warning times can increase deaths. Weather experts aren’t sure why, but worry that people think that if a twister hasn’t appeared in a certain amount of time, it must have been a false alarm.

Yet a long-track tornado can be on the ground for 30 miles.

“If you have a basement, you don’t need 20 minutes warning, but if you are in a mobile home park you may need more than 20 minutes to find a shelter,” commented Alan W. Black, a University of Georgia doctoral student and co-author with Ashley of a recent study of tornado and wind fatalities.

Jerry Brotzge, a research scientist at the Center for Analysis & Prediction of Storms, University of Oklahoma, said many people who hear warnings will look outside to see if they can see the tornado _ “they need some kind of confirmation, they want to see it.”

But the Joplin tornado was at least partly rain-wrapped, meaning that a powerful rainstorm obscured it from some directions and “they wouldn’t have seen it coming.”

“Even when people are sheltered in their homes, if they are not underground they can die,” Brotzge added.

But asking people to evacuate an area is also a difficult decision, he said, “what if you have a traffic jam and the tornado hits that.”

Ashley concluded: “The take-home is, people have to take personal responsibility for their lives.”

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