"These changes in the mid-South area are important because we have extremely vulnerable populations there, with a lot of people living in mobile homes," Gensini said. "The change we saw is one tornado per county per decade, so it's not a big trend, but given how rare tornadoes are, it's a significant upward increase."
The researchers are not yet sure what is driving this shift.
What is certain, however, is the best way to remain safe. An oft-repeated tip for tornado survival is to seek shelter in a basement, but Marsh said this is something of a myth.
“If you have a basement available, then that’s absolutely a good choice, but it’s one of the biggest pieces of misinformation out there that you need to be below ground to survive a tornado," he said.
Instead, people should try to take cover in a permanent, well-built — and ideally, reinforced — structure on the lowest floor, because winds in a tornado tend to be less violent closer to the ground, according to Marsh.
Then, he said, take cover as much as possible.
“The more walls that are standing between you and the outside — those walls will absorb most of the debris,” Marsh said.
With many cities across the U.S. dealing with changing population densities and the expanding bull's-eye effect, people should be mindful of the risks of extreme weather, no matter which region of the country they reside in, said J. Marshall Shepherd, director of the atmospheric sciences program at the University of Georgia in Athens.
“A lot of places that aren’t prone to tornadoes or aren’t experienced with extreme weather might not even know how to respond," Shepherd said, "but one message I have is that no matter where you live, you should think about what your plan of action is if there’s a future tornado.”
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