2 Atlantic storms may soon collide. Rare ‘Fujiwhara effect’ shapes what happens next

The hottest couple in the Atlantic right now are tropical storms Philippe and Rina.

The two systems have been inching closer to each other for days, and with less than 500 miles separating them on Friday morning, forecasters have started predicting they’ll do something relatively rare in the meteorological world. It’s called the Fujiwhara effect.

That’s the formal name for the interaction between two tropical storms or hurricanes. When they get close enough, they begin “an intense dance,” as the National Weather Service puts it, around a common center.

And there can be a few different outcomes. The stronger storm can absorb the weaker one and whirl away a little more powerful. Or they can spin with each other for a bit before shooting off in two different directions again as independent storms. In rare cases, the pair can merge into an even bigger, stronger storm.

That makes forecasting what happens next tough, and the National Hurricane Center said Friday there’s “larger-than-normal uncertainty in Philippe’s future track.”

Bryan Norcross, hurricane specialist at Fox Weather, said Friday morning that Philippe and Rina were doing the do-si-do east of the Caribbean islands.

“The winner of the dance isn’t yet clear, but Rina is likely not a threat. Philippe is still a maybe, though most forecasts keep it away from the islands. Stay aware,” he posted on X, the social media site formerly known as Twitter.

The latest forecast calls for Philippe to basically halt over the Atlantic, while Rina veers north and ultimately dissipates over the open ocean. Philippe’s forecast path also curls it northeast, away from most land.