Breakdown: Why one hurricane can change the path of another

Breakdown: Fujiwhara Effect

MEMPHIS, Tenn. (WMC) - This hurricane season, there were two tropical pretty close to one another, storms Marco and Laura. Both made landfall along the Gulf Coast and took similar paths. Many asked the question, if they would collide and form one monstrous storm. That’s not exactly the case but systems can and do interact with each other, if they are close enough.

The Effect is called the Fujiwhara Effect. It was discovered by a Japanese Meteorologist back in 1921. Believe it or not, it isn’t as rare as you may think but we often don’t notice it. It usually occurs with a bigger system that overtakes a weaker unorganized system.

If two storms get close or are less than 900 miles apart, they can start to orbit one another or dance around each other. What happens after they orbit, will depend on size and intensity. If they are similar size and strength the two storms will rotate around a central point between the two. On rare occasions, storms can change directions of one or both of the cyclones.

An example of the Fujiwhara effect from the eastern Pacific Ocean. This satellite animation shows Hurricanes Irwin and Hilary rotation around each other in the east Pacific in late July 2017 before dissipating as they moved farther northward.
An example of the Fujiwhara effect from the eastern Pacific Ocean. This satellite animation shows Hurricanes Irwin and Hilary rotation around each other in the east Pacific in late July 2017 before dissipating as they moved farther northward. (Source: NOAA/National Weather Service)

The exact results will also depend on the prevailing atmospheric conditions.

If there is one stronger storm and a weaker one, then the weaker will rotate around the stronger storm. The bigger storm can absorb the smaller storm but that doesn’t mean it will become a massive or bigger storm.

This effect doesn’t apply to just tropical systems but to low pressure systems and other vortices as well.

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