'Dixie Alley' as dangerous as the better-known Tornado Alley, say scientists

As the US Southeast continues to endure an onslaught of severe thunderstorms and tornadoes, a recent study of tornado patterns in the US points to Smith County, Miss., as the tornado-risk capital of the United States.

For generations raised on the notion of a "Tornado Alley" in the US – running roughly from northern Texas, through the eastern Great Plains, and into the western Great Lakes states – the results may come as something of a surprise.

National Weather Service forecasters have long warned that while some areas have higher risks of tornadoes than others, every state in the union experiences twisters. States within Tornado Alley, along with Florida, have been viewed as the areas with the highest risk.

In the new analysis, the five counties in the eastern US facing the highest tornado risk – in this case, a high probability that in any two-year period, three tornadoes will track through the same 20-mile radius – include counties in Nebraska, Oklahoma, and Arkansas.

But Smith County topped the list.

Beyond the risk any individual county may face, perhaps the biggest surprise was the sheer breadth of the country at an elevated risk for tornadoes, says Grady Dixon, an assistant professor of meteorology and climatology at Mississippi State University.

"I knew going in that the southeast was going to have a generally elevated amount of risk," he says. "What I was surprised about was the east-west span of this elevated risk, stretching all the way to the Carolinas."

In effect, Tornado Alley in this study becomes a patchy blotch over much of the central and southeastern US.

"When you say 'tornado alley,' people think Great Plains, and rightfully so," he says. But from a hazard-assessment perspective, "we don't think it's wise to consider the Southeast as a separate entity or some sort of afterthought."

The aim of the study was to focus less on the location of the five or so most significant "bullseye" counties and more on where the areas of relatively higher and lower risk are in the broader regions the study covers.

Still, the magnitude of the risk in the area around Smith County was perhaps the biggest surprise.

Looking at tornado data with other techniques might shift the location of that high-risk location somewhat, he says. But the results indicate that the area should experience on average "more than one tornado every single year in any given 20-mile radius."

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