Tornadoes are becoming more frequent east of the Mississippi River, putting more people at risk
States in the Midwest and South have already seen many deadly tornadoes so far this year. These parts of the country are also where the number of severe events are steadily increasing.
“In like a lamb, out like a lion” goes the old saying about March.
The night of March 31 in southwest Indiana’s Sullivan County — the weather roared. An EF3 tornado touched down killing three people and destroying more than 200 structures.
“It was coming right at us and that sound they say that you hear of the train. That is something I’ll never get out of my head,” said Sullivan County Councilwoman Jackie Monk. “We just don’t experience this. I mean we get straight line winds, things like that, but this is just unheard of.”
Portions of the Midwest and South have already gotten a heavy dose of tornadoes this year; 22 people in Mississippi, 10 in Tennessee and nine in Alabama have died from the storms. Arkansas, Missouri, Illinois and Indiana each have recorded a handful of deaths from tornadoes.
These parts of the country, especially those east of the Mississippi River, are also where the frequency of tornadoes is increasing, according to Victor Gensini, an associate professor of meteorology at Northern Illinois University, who studies the kinds of storms that produce tornadoes.
“We are essentially more vulnerable as we move further east, because we have greater population density, we have more assets, a bigger human exposure,” Gensini said.
He first published research in 2018 identifying this eastward trend and said the findings have remained consistent since. That means the threat of tornadoes is present in areas less accustomed to the dangerous weather events.
“We need to get away from this notion of ‘I live in Tornado Alley versus you don’t’ or ‘It’s December, let’s not worry about tornadoes,’” he said. “All it takes is one.”
Councilwoman Monk said she heard from many people in and near Sullivan who were surprised the storm hit their community. Many have thought they were protected by the 200 foot tall Merom Bluff on the Wabash River a few miles to the west.
“I don’t know if it’s an old wives’ tale, but many generations have always heard that a storm will bounce off that bluff and go north or south,” she said.
The storm that hit Sullivan County was the worst tornado event on record there, according to historic historical data from the National Oceanic and Atmospheric Administration. An F3 tornado swept through the region in 1963 but the historical report doesn’t list any deaths or injuries.
Monk, whose own house was spared with only minimal damage, said in the days since the tornado there’s been an outpouring of support from within Sullivan and the surrounding community to help with the area’s recovery.
“Many people have just opened up their hearts and their homes,” she said. “We have a long road ahead of us. This isn’t going to be something that we can fix in a couple months. It’s going to be a year or better getting through all this.”
Forecasting challenges and successes
Already, 2023 is one of the most deadly years for tornadoes in the past decade, according data to NOAA’s storm prediction center — and that’s before April, May and June when tornadoes most frequently form.
But that doesn’t guarantee the rest of the spring will be as intense.
“Seasonal forecasting is very difficult, especially in the spring,” said Herald Brooks, a senior research scientist at NOAA’s National Severe Storm Laboratory.
Tornadoes need two specific weather conditions to form: warm moist air near the ground with cool dry air above and wind speeds that get stronger and change direction the higher they are in the atmosphere, he said.
Spring is the time of year when these conditions are generally more present, but, critically, tornadoes won’t form without both, Brooks added.
“Are we having lots of wind shear when the moisture is available or not?” he said. “Because it’s possible to have it be warmer than normal on average and have more wind shear on average, but if you look at the day-to-day combinations, they’re out of phase with each other.”
The scale of tornado destruction also complicates sweeping predictions or characterizations about the number or intensity of tornadoes over a course of a single season or entire year, Brooks said.
“I don’t think the people in Little Rock, Arkansas, that were impacted by a tornado really care if the season is going to be above or below average,” he said. “They were hit.”
While scientists gravitate toward measuring the frequency and intensity of storms, Gensini argues that in many ways that misses the point.
“At the end of the day what really matters is casualties, number of businesses and homes impacted, insured losses,” he said. “That’s what really impacts society.”
To that end, Gensini said his field has made major advancements in shorter-term predictions. Forecasters are now able to accurately anticipate severe weather events in multi-state regions as many as 10 days in advance, thanks to leaps in computational power and the ability to use computers to simulate the atmosphere, he said.
“We would never be able to be thinking about doing that 30 years ago,” he said. “Ten years ago it would have been a pipe dream. Here we are a decade later and we’re making skillful, accurate forecasts.”
That’s helping save people’s lives, Gensini said, because social media, radio and TV all communicate the potential for severe weather. There’s still some room for improvement, but he said he’s encouraged by conversations he had in recent weeks with non-meteorologists who knew of the tornado threat far ahead of time.
This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest. It reports on food systems, agriculture and rural issues. Follow Harvest on Twitter: @HarvestPM.