The Rare World Of Anticyclonic Tornadoes

Did you know 90% of tornadoes spin in the same direction?

But every once in a while, nature flips the script.

These rare storms are called anticyclonic tornadoes, and they behave in a unique way.

Let's Break It Down

Most tornadoes are cyclonic, meaning they rotate in the same direction as the storm’s larger rotation. In the Northern Hemisphere, that means a counterclockwise rotation.

An anticyclonic tornado, on the other hand, spins clockwise.

They usually form in very specific setups where the atmosphere is already highly unstable and wind patterns are complex.

One of the most common ways they develop is within supercell thunderstorms, which are rotating storms with strong updrafts. 

Under certain conditions, smaller pockets of rotation can spin the opposite way. If one of those pockets tightens and reaches the ground, an anticyclonic tornado forms.

(MORE: Supercell Spawns Anticyclonic Tornado In Illinois)

Another important clue: They often form in areas where storm interactions are messy, like boundaries between different air masses or within storm splits.

Why Are They Uncommon?

The atmosphere has a bit of a “default setting” thanks to Earth’s rotation (the Coriolis Effect) and typical wind shear patterns. In most severe storms, that setup strongly favors cyclonic rotation.

For an anticyclonic tornado to form, unusual conditions have to line up just right:

• Abnormal wind shear structure
• Storm splitting in a specific way
• A rare balance of inflow and updraft dynamics

“We just don't typically see that set up in North America because of the way our weather patterns move and because of the direction of wind for a lot of these systems,” notes meteorologist Sara Tonks.

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Anticyclonic tornadoes frequently appear as satellite tornadoes, meaning they form near a larger, dominant tornado rather than on their own.

“Usually when you see an anticyclonic tornado, it's one of those smaller satellites,” explains Tonks. “While these are rated much lower intensity than the main tornado, it's still adding to the overall damage and threat.”

It's important to note that anticyclonic tornadoes can be just as strong, fast and capable of producing significant damage as their cyclonic counterparts.

Their rarity doesn’t make them less dangerous, it just makes them less common and harder to study.

The Takeaway

Anticyclonic tornadoes are rare, often short-lived and frequently overshadowed by larger storms nearby. But they are not harmless or unusual in behavior once they form.

“A tornado is a tornado, no matter what direction it is spinning. It is still extremely dangerous,” says Tonks. “There's a lot that we don't know, which means there's a lot to learn.”