Meteorologists say this year’s warm winter was a key ingredient for deadly tornadoes in the Midwest

By | March 16, 2024

This winter’s record warmth provided the key ingredient for an outbreak of deadly tornadoes and damaging gorilla hail that hit parts of the Midwest on Wednesday and Thursday, tornado experts said.

Thursday’s tornado outbreak in Ohio, Kentucky, Indiana and Arkansas killed at least three people, a day after large hail hit Kansas. It’s a bit early, but not unprecedented, for such a tornado outbreak usually associated with May or April, but that’s also due to the hottest winter on both U.S. and global records, meteorologists said.

“To get severe storms this far north at this time of year, it has to be warm,” said Victor Gensini, a professor of meteorology at Northern Illinois University.

TORNADO RECIPE

For tornadoes and large hail storms to form, two key ingredients are needed: wind shear and instability, according to Gensini and National Severe Storms Laboratory scientist Harold Brooks.

Wind shear, which is when the wind spins in different directions and speeds as they rise in altitude, is usually present all winter and much of spring because it is a function of the normal temperature difference we see across the country, said Gensini.

But instability, that is, that juicy warm, moist air close to the ground that characterizes summer, is usually missing this time of year, Gensini and Brooks said.

That’s because normally in winter and early spring, Arctic air plunges south and pushes warm, moist air south into the Gulf of Mexico, leaving dry, stable, cool air in place, said Matt Elliott, the National Oceanic and Atmospheric Administration Warning Coordination Meteorologist. And that cool, stable air keeps tornadoes and large hail from forming.

But not this year. There was only one real explosion in the Arctic this year and that was two months ago, the meteorologists said.

“When it’s warmer than normal, we tend to get more warm tornadoes in the winter,” Brooks said. “It’s not necessarily a causal effect. Maybe they both happen because of the same thing.”

STORMY MIDDLEWEST

Hunter Vance, 27, of Lakeview, Ohio, was on the phone with a friend when the sirens started blaring. So he took shelter in his bathtub for twenty minutes. Then he came out to see the devastation.

He remembers last year’s bad weather, but not so early.

“And it’s never been worse than this,” he added.

Gensini has identified five tornadoes or major outbreaks in the Midwest or Great Lakes region in the past five weeks, which he said is unusual: Wisconsin gets its first-ever February tornado on Feb. 8; 32 tornadoes, including one a quarter mile from his home on February 27; large hail and a tornado around the Illinois-Iowa border on March 4; the 4-inch gorilla hail and several tornadoes on March 13 and the March 14 tornadoes that killed at least three people in Ohio and affected elsewhere in the Midwest.

Tornado activity is much more common this time of year in the south, and what’s happening “much further north than we normally expect,” Gensini said.

NOAA’s Elliott said it may be a little early, but this is about the time of year when severe storms start to build up in the Midwest, but they usually don’t peak until May.

What happened this week “is really a typical spring event,” Elliott said.

Even after Thursday, the year is running slightly below normal in the number of tornadoes and tornado fatalities, according to NOAA’s Storm Prediction Center. Before Thursday, tornadoes had killed only two people, which is far fewer than the fifteen-year average of twelve before March 14.

EL NINO FACTOR

What also makes the outbreaks in the Midwest unusual is that an El Nino is happening, even as it begins to fade. The natural El Nino, a warming of the central Pacific Ocean that is changing weather worldwide, often leads to fewer severe storms in the Midwest, especially in the spring, studies show.

That is not the case.

Gensini, who co-authored one of the studies, and Adam Sobel of Columbia University, who wrote another, both said the El Nino factor is just one of many variables and only slightly tilts the odds.

Brooks said he doesn’t really trust El Nino as a spring signal.

CLIMATE CHANGE

No one has done the traditional scientific studies linking specific tornado outbreaks to human-induced climate change. There are so many issues that make that difficult, including poor tornado records in the past and tornadoes being minor weather events for global climate models.

And among all the severe weather events like floods, hurricanes, droughts and heat waves, tornadoes are one of the trickier problems associated with climate change. There may be something there, but it’s probably only a minor factor, Brooks said.

But given the anomalous temperatures and other climate variables, Gensini said, “If there was ever a fingerprint of climate change on severe weather, it would be this year.”

Gensini has not done any formal attribution research, but said, “If you look at the recent February and Marches in terms of the number of tornadoes, it’s pretty easy to see that there’s a change happening,” compared to the effect of steroids on baseball. home runs in the 1990s and early 2000s.

MORE COMING SOON

Due to other natural climate factors, Gensini said there is a high chance of another outbreak of tornadoes in the Midwest in late March or early April.

After that, Gensini said it could be a busy tornado spring for the Midwest, but there’s also a chance the Midwest will skip spring and go straight to summer climate-wise and then the storms will subside.

Last year, tornado activity through April was as much as double the average and “then May was completely dead,” NOAA’s Elliott said.

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Joshua Bickel contributed from Lakeview, Ohio.

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