SMART NEWS

Rare Tornado Spinning the ‘Wrong’ Direction Forms Over Oklahoma

A powerful anticyclonic tornado uprooted trees and damaged some buildings on the night of April 30, and a second unusual twister changed direction, doubling back on its path

Sarah Kuta

Daily Correspondent

Tornado debris and damage
The tornadoes uprooted and snapped some trees, but fortunately, no injuries or deaths have been reported. Tillman County Emergency Management

In the Northern Hemisphere, the vast majority of tornadoes spin counterclockwise. But in rare cases—just 1 to 2 percent of the time—they rotate the “wrong” way, moving clockwise instead.

That’s exactly what happened this week when powerful thunderstorms raged across southwestern Oklahoma. Meteorologists were surprised to see this rare weather phenomenon—called an anticyclonic tornado—on the evening of April 30 in Tillman County, just across the border from Texas.

Its unconventional spin aside, the anticyclonic tornado was also unusual because, for a while, it was “nearly stationary,” according to the National Weather Service (NWS). That alone is uncommon, as tornadoes typically move in the same path as their parent thunderstorm. And while most anticyclonic tornadoes are brief and feeble, this one was incredibly powerful, with radar showing it had lifted debris thousands of feet into the air, per CNN’s Mary Gilbert.

A popular explanation for the standard, counterclockwise spin of tornadoes has been forces related to Earth’s rotation, a phenomenon known as the Coriolis effect. But Jana Houser, a supercell thunderstorm and tornado radar analysis expert at Ohio State University, tells Smithsonian magazine’s Catherine Duncan that this idea is wrong. Tornadoes are too small and too short-lived to be affected by the Coriolis force.

Instead, she says, a tornado’s rotation comes from variations in the speed and height of vertical winds. Tornadoes sometimes spin clockwise because of “a very strong surge of air within the storm.”

The anticyclonic tornado wasn’t the only unusual feature to result from Tuesday’s thunderstorms in Oklahoma. Separately, another tornado behaved abnormally when it circled back and retraced its own path north of Loveland, Oklahoma, around 10 p.m.

Tornadoes usually move from west to east, since that’s the direction of the prevailing winds in the United States. After traveling east, however, this particular tornado slowed down, turned north and then began traveling west, recrossing the route it had just taken. Looping tornadoes, like this one, have the potential to cause catastrophic destruction, as one did in Greensburg, Kansas, in May 2007.

At one point, both of the unusual tornadoes—the anticyclonic and the looping tornado—were briefly spiraling at the same time.

“You certainly don’t see this every day,” says Rick Smith, a meteorologist with the National Weather Service in Norman, Oklahoma, to CNN.

Fortunately, the area where the tornadoes struck was mostly farmland, and no injuries or deaths have been reported. However, the storm did snap or uproot some trees, flooded county roads and damaged a few buildings at the local golf course and airport, according to Tillman County Emergency Management. The storm also damaged a historic hangar used by the WWII Airborne Demonstration Team, a nonprofit that honors World War II veterans.

Spring kicks off tornado season in the United States, though dangerous twisters can form all year long, FOX Weather’s Brian Donegan reported in March. May tends to be the most active month, followed by April and June. More than half of all tornadoes recorded between 1991 and 2020 took place in April, May and June. On average, the U.S. sees roughly 1,333 tornadoes per year.

This year, however, weather experts are predicting an especially busy year for tornadoes. The anticipated uptick is due, at least in part, to El Niño’s likely transition to La Niña in the coming months.

“We’re coming off a very strong [El Niño], but we’re forecast to fade out very quickly,” says Victor Gensini, a meteorologist at Northern Illinois University, to the Washington Post’s Matthew Cappucci. Scientists don’t have many examples of this kind of transition, “but those that we do have generally support above-average activity,” he adds. As for exactly where this tornado activity may appear, experts aren’t yet sure.

At least 300 tornadoes were recorded in April, which far outpaced the April average of 182, reports the Washington Post’s Ian Livingston. It was the second-highest number of tornadoes ever recorded for the month, trailing only behind 757 in April 2011.

Editor’s Note, May 6, 2024: This article has been updated to emphasize the scientific consensus that the spin of a tornado is largely not determined by the Coriolis effect.

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Sarah Kuta

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.