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

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.

Researchers have long attributed the standard, counterclockwise spin of tornadoes to 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 explanation is wrong.

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