Tornado frequency increasing in the east, study finds

NORMAN, Okla. - A new study has found a shift in tornado frequency, with an increase in states along the Mississippi River and decreasing in Oklahoma and Texas.

The study was co-authored by Victor Gensini, a professor of atmospheric sciences at Northern Illinois University, and Dr. Harold Brooks, a senior research scientist with the National Severe Storms Laboratory with the National Weather Service in Norman.

"One of the things we’ve been interested in for a long time, trying to find ways we can understand why tornadoes have changed — if they’ve changed over time," Brooks said. "It’s a hard thing to do,in large part because we collect the reports differently. We pay more attention now. We have more awareness, so the reports change all of the time for reasons that have nothing to do with the weather."

The study includes data from 1979 through 2017.

"The biggest thing we found was that, when we look both at reports processed the right way and we look at the environmental conditions that storms form in — the kinds of things we would use to forecast that tornadoes are going to occur — we found that both of them see an increase in the frequency of occurrence of tornadoes in the mid-south, so Tennessee, Mississippi, eastern Arkansas and it’s decreased in Texas and Oklahoma over the last 40 years," Brooks said. "If we looked over a decade, we would see maybe 5 percent fewer tornadoes or 10 percent, depending on exactly where you look."

However, he told News 4 on Wednesday the reasoning behind the apparent shift remains an unanswered question.

"We see the change, and it corresponds with a time in which we’ve seen the planet warm, so there’s a real temptation to associate it with global warming but it’s not clear that’s what’s going on. There may be larger long-time scale changes that take place in the atmosphere we can’t figure out yet," Brooks said.

Even so, the results from the study does not mean Oklahoma will ever tornado-free, experts said.

"I think, for Oklahomans, the biggest takeaway is whether or not there is a shift in tornadoes… a subtle shift... from the central or eastern U.S. in Oklahoma, the meteorology and the geography will basically not change. That means we still have the probability of having the higher-end tornadoes, which represent a bigger threat to life and property," said KFOR chief meteorologist Mike Morgan.

For a link to the study, click here.