Can two tropical systems collide? The Fujiwhara Effect explained

Hurricanes Imelda and Humberto are churning in the western Atlantic. As of Tuesday morning, they are located a little over 400 miles from one another.

Initially, it could appear that the two storms will merge to generate a mega-hurricane, but this is not the case, due to the Fujiwhara Effect. 

So why does this happen? In short, the two low pressure systems rotate around a common center point. 

What is the Fujiwhara Effect?

Named for Sakuhei Fujiwhara, a Japanese meteorologist who first noticed storms’ interactions in the 1920s. He theorized that two storms could rotate around a common point and influence tracks of the storms. Fujiwhara was proven correct.

In some instances these storms look like they are “dancing” with one another. 

Bay News 9’s Chief Meteorologist Mike Clay says we should not be concerned about these storms colliding and forming a mega-hurricane. “In the Atlantic, if two tropical systems are close enough, they can ruin the environment for both, just like we are seeing right now with Humberto and Imelda. There just isn’t enough ocean space.”

The smaller or weaker storm will usually circle around the bigger one, as the larger storm will eventually dominate or potentially even fully absorb the smaller system.

Imelda, in this case, is the larger storm and is expected to fully absorb Humberto over the next day or so. Wind shear, or the change in wind speed and direction with height, is usually created from the interaction, killing one or both storms.

2023 Atlantic Ocean Fujiwhara Effect

Clay says this effect is rare and commonly occurs in the Pacific Ocean because it is the larger ocean, but it can happen in any ocean. 

Nearly two years ago, a similar occurrence was taking place in the Atlantic Ocean, albeit with weaker storms. Tropical Storms Philippe and Tropical Storm Rina were both located east of the Leeward Islands. 

They began to do the “dance” of the Fujiwhara Effect and eventually, the stronger storm – Philippe weakened Rina. 

For interests in the tropics, here is what we are currently tracking. 

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