Gyre could jump-start tropical activity ahead of hurricane season

The first tropical storm of the year could spin up later in May before the official start of the Atlantic hurricane season begins on Sunday, June 1.

The first tropical storm of 2025 could spin up before the official start of the Atlantic hurricane season, kicking off what is predicted to be a dynamic year for hurricanes.

Around the middle of May, a large, slow-spinning area in the atmosphere could develop somewhere around Central America, overlapping with part of the Caribbean and eastern Pacific Ocean. This phenomenon, known as the Central American Gyre, can sometimes lay the groundwork for a tropical depression or tropical storm to take shape.

This is the best chance so far this year for the first named tropical storm of 2025 to develop, both in the Caribbean and in the eastern Pacific, although AccuWeather meteorologists currently say the odds of development are low.

"We're starting to get into that season where we need to kind of keep an eye out [in the Caribbean]," AccuWeather Lead Hurricane Expert Alex DaSilva said.

"At the very least, a wetter pattern down across Central America and then up into the Western Caribbean is expected," DaSilva added.

Tropical downpours could cause localized flooding across Central America, Jamaica, Cuba and other islands across the western Caribbean. Some downpours could also reach South Florida.

"We're coming out of the winter season, so we want people to start transitioning their mindset into tropical mode as we head to the end of May, because there could be something lurking down there in the middle to late portions of the month," DaSilva added.

Where would it go if something develops?

If the gyre does spawn a tropical depression or tropical storm in the Caribbean, it is likely to track northeastward.

"Given the pattern, I think the most likely is it would just cross, cross over Jamaica, Cuba, and then head out to sea," DaSilva said. "Right now, it does not look like it would be heading towards the United States."

Recent history of tropical activity in May

Outside of the traditional Atlantic hurricane season, which runs from June through November, May is the most common month for tropical storms to develop. Since 2015, there have only been four years when a tropical system did not spin up in May.

Warming water in late spring can set the stage for development, particularly in the Caribbean, eastern Gulf and western Atlantic. Additionally, a slow-moving cold front or a dip in the jet stream can reach far enough south and linger long enough for storms to form in these zones.

Tropical Storm Bertha was the most recent storm to make landfall in the United States in May after it hit South Carolina in 2020. This came less than two weeks after Tropical Storm Arthur made a close swipe along the coast of North Carolina, but the center of the storm never made landfall as it curved out to sea.

A closer look at the gyre

Whether or not a gyre takes shape over Central America could hinge on the jet stream.

"Essentially, what's happening is we're going to be getting a dip in the jet stream to come down into the southeastern United States during the middle of May," DaSilva explained. The question is whether the dip in the jet stream is strong enough and reaches far enough south to initialize the gyre and get it spinning.

He added that disruptive winds, known as wind shear, could also be lower—another reason AccuWeather forecasters are monitoring the region for potential tropical development.

Last June, a gyre helped with the formation of Tropical Storm Alberto, which made landfall along Mexico's Gulf coast shortly after the middle of the month.

A gyre also developed near the western Caribbean in June of 2023, although it did not lead to a named tropical storm.

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