UNITED STATES NEWS

Study says warming-fueled supercells to hit South more often

Mar 27, 2023, 10:37 PM

America will probably get more killer tornado- and hail-spawning supercells as the world warms, according to a new study that also warns the lethal storms will edge eastward to strike more frequently in the more populous Southern states, like Alabama, Mississippi and Tennessee.

The supercell storm that devastated Rolling Fork, Mississippi is a single event that can’t be connected to climate change. But it fits that projected and more dangerous pattern, including more nighttime strikes in a southern region with more people, poverty and vulnerable housing than where storms hit last century. And the season will start a month earlier than it used to.

The study in the Bulletin of the American Meteorological Society predicts a nationwide 6.6% increase in supercells and a 25.8% jump in the area and time the strongest supercells twist and tear over land under a scenario of moderate levels of future warming by the end of the century. But in certain areas in the South the increase is much higher. That includes Rolling Fork, where study authors project an increase of one supercell a year by the year 2100.

Supercells are nature’s ultimate storms, so-called “Finger of God” whoppers that are “the dominant producers of significant tornadoes and hail,” said lead author Walker Ashley, a professor of meteorology and disaster geography at Northern Illinois University. Tall, anvil-shaped and sky-filling, supercells have a rotating powerful updraft of wind and can last for hours.

Supercells spawned the 2011 super outbreak that killed more than 320 people in Alabama, Mississippi and Tennessee, the Mid-South.

The study used computer simulations to predict what will happen by the end of the century with different levels of global carbon pollution levels. But Ashley said that stormier future seems like it’s already here.

“The data that I’ve seen has persuaded me that we are in this experiment and EF-4 tornado killed more than 20 people in Mississippi on Friday. “What we’re seeing in the longer term is actually occurring right now.”

Ashley and others said although the Mississippi tornado fits the projected pattern, it was a single weather event, which is different than climate projections over many years and a large area.

Ashley and study co-author Victor Gensini, another meteorology professor at Northern Illinois University and a longtime tornado expert, said they are watching the potential for another supercell blow-up in the Mid-South on Friday.

Past studies have been unable to forecast supercells and tornadoes in future climate simulations because they are small-scale events, especially tornadoes, that global computer models can’t see. Ashley and Gensini used smaller regional computer models and compensated for their reduced computing power by spending two years running simulations and crunching data.

Three scientists not connected to the study said it makes sense. One of them, Pennsylvania State University tornado scientist Paul Markowski, called it a promising advance because it explicitly simulated storms, compared to past research that only looked at general environments favorable to supercells.

While the study finds a general increase in supercell counts, what it mostly finds are large shifts in where and when they hit — generally, more east of Interstate 35, which runs through east central Texas, Oklahoma and Kansas, and fewer to the west.

In moderate warming – less warming than the world is headed for based on current emissions – parts of eastern Mississippi and eastern Oklahoma are projected to get three more supercells every two years, with eastern Texas, Arkansas, Louisiana, Alabama, western Tennessee and eastern Georgia getting one more supercell every other year.

With worst-case warming — more than the world is presently on track for — the study projects similar changes but with worsening supercells over eastern Oklahoma, Arkansas and southern Missouri.

Cities that should see more supercells as warming worsens include Dallas-Fort Worth, Little Rock, Memphis, Jackson, Tupelo, Birmingham and Nashville, Ashley said.

The moderate warming simulation projects 61% more supercells in March and 46% more in April, while the more severe warming scenario has 119% more in March and 82% more in April. They see double-digit percentage point drops in June and July.

In the mid-South, including Rolling Fork, the study projects supercell activity peaking two hours later, from 6 to 9 p.m. instead of 4 to 7 p.m. That means more nighttime supercells.

“If you want a disaster, create a supercell at night where you can’t go outside and visually confirm the threat’’ so people don’t take it as seriously, Gensini said.

The eastward shift also puts more people at risk because those areas are more densely populated than the traditional tornado alley of Kansas and Oklahoma, Ashley and Gensini said. The population coming under more risk is also poorer and more frequently lives in mobile or manufactured homes, which are more dangerous places in a tornado.

What’s likely happening as the climate warms is the Southwest United States is getting hotter and drier, Ashley and Gensini said. Meanwhile, the Gulf of Mexico, which provides the crucial moisture for the storms, is getting hotter and the air coming from there is getting juicier and unstable.

The hot dry air from places like New Mexico puts a stronger “cap” on where storms would normally brew when air masses collide in spring time. That cap means storms can’t quite boil over as much in the Great Plains. The pressure builds as the weather front moves east, leading to supercells forming later and farther eastward, Gensini and Ashley said.

Because February and March are getting warmer than they used to be this will happen earlier in the year, but by July and August the cap of hot dry air is so strong that supercells have a hard time forming, Ashley and Gensini said.

It’s like playing with a pair of dice loaded against you, Ashley said. One of those dice is making the odds worse because of more people in the way and the other one is loaded with more supercells “increasing the odds of the perils too, tornadoes and hail.”

___

Follow AP’s climate and environment coverage at https://apnews.com/hub/climate-and-environment

___

Follow Seth Borenstein on Twitter at @borenbears

___

Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

United States News

Two women hug as Muslim and Jewish women gather at an interfaith workshop on the Israeli-Palestinia...

Associated Press

In US, some Muslim-Jewish interfaith initiatives are strained by Israel-Hamas war

Shireen Quaizar was wracked with doubt. For years, the school psychologist has been active in Muslim-Jewish interfaith dialogue, but the Israel-Hamas war left her reeling. “What are we doing with talking to each other?” she recalled thinking, frustrated by a conversation about the exact number of Palestinians killed in an Israeli airstrike. “This doesn’t work.” […]

2 hours ago

FILE - Rep. George Santos, R-N.Y., leaves the Capitol after being expelled from the House of Repres...

Associated Press

Republicans had New Yorkers lead the way in expelling Santos. Will it help them keep the majority?

WASHINGTON (AP) — George Santos is gone from the House, but his name is certain to pop up in key congressional races across New York next year. Democrats are targeting five seats held by first-term Republicans and looking to associate them with their former colleague in the state’s congressional delegation as often as they can. […]

2 hours ago

This photo provided by Mattel shows a Barbie doll of Wilma Mankiller. Toy maker Mattel is honoring ...

Associated Press

Barbie doll honoring Cherokee Nation leader is met with mixed emotions

OKLAHOMA CITY (AP) — An iconic chief of the Cherokee Nation, Wilma Mankiller, inspired countless Native American children as a powerful but humble leader who expanded early education and rural healthcare. Her reach is now broadening with a quintessential American honor: a Barbie doll in the late Mankiller’s likeness as part of toymaker Mattel’s “Inspiring […]

10 hours ago

Notes from students expressing support and sharing coping strategies paper a wall, as members of th...

Associated Press

Lacking counselors, US schools turn to the booming business of online therapy

Trouble with playground bullies started for Maria Ishoo’s daughter in elementary school. Girls ganged up, calling her “fat” and “ugly.” Boys tripped and pushed her. The California mother watched her typically bubbly second-grader retreat into her bedroom and spend afternoons curled up in bed. For Valerie Aguirre’s daughter in Hawaii, a spate of middle school […]

10 hours ago

Associated Press

Authorities identify suspect in killing of 3 homeless men in Los Angeles

LOS ANGELES (AP) — A Los Angeles man already in custody in connection with another shooting investigation has been identified as the suspect in three recent killings of homeless men, police said Saturday. Los Angeles Police Chief Michel Moore said Jerrid Joseph Powell, 33, was identified as the suspect in the three killings after authorities […]

16 hours ago

Associated Press

Report: Contaminants being removed from vacant Chicago lot where migrant housing is planned

CHICAGO (AP) — High levels of mercury and other contaminants are being removed from a vacant Chicago lot where a tent camp housing 2,000 migrants is planned, a report from a consultant hired by the city said. The Chicago Tribune reported that the nearly 800-page assessment by Terracon Consultants released Friday night said high levels […]

17 hours ago

Sponsored Articles

(KTAR News Graphic)...

KTAR launches online holiday auction benefitting Boys & Girls Clubs of the Valley

KTAR is teaming up with The Boys & Girls Clubs of the Valley for a holiday auction benefitting thousands of Valley kids.

...

Dierdre Woodruff

Interest rates may have peaked. Should you buy a CD, high-yield savings account, or a fixed annuity?

Interest rates are the highest they’ve been in decades, and it looks like the Fed has paused hikes. This may be the best time to lock in rates for long-term, low-risk financial products like fixed annuities.

Follow @KTAR923...

West Hunsaker at Morris Hall supports Make-A-Wish Foundation in Arizona

KTAR's Community Spotlight this month focuses on Morris Hall and its commitment to supporting the Make-A-Wish Foundation in Arizona.

Study says warming-fueled supercells to hit South more often