A weather feature called the Central American Gyre is the main reason a tropical system could develop near the Gulf next week. If you haven't heard of this term before, you're not alone. Research from the State University of New York only coined the term "Central American Gyre" in 2017.
Central American Gyres are broad areas of counterclockwise winds rotating around a weak zone of low pressure. The center of the gyre can form over land or water, but is almost always within 600 miles of the coast of Central America. These gyres are many hundreds of miles across and influence the weather across the entire western Caribbean and Gulf of Mexico, including Florida. These gyres typically move slowly from southeast to northwest across Central America and cause heavy rain and flooding. One or two gyres form per year on average, most often in May through June and September through November.
Why do Central American Gyres matter to us? Quite often, they aid or even cause tropical development. Tropical storms or hurricanes can form on the east side of the gyre in the Caribbean or the west side of the gyre in the Pacific. We saw an example of this just last year. Hurricane Nate was the fourth storm to hit the U.S. in 2017 and developed on the east side of a Central American Gyre on October 4th. Nate was the deadliest storm in the history of Costa Rica and caused an estimated $225 million in damage in the United States.
Exactly one year after Nate, we are seeing another Central American Gyre take shape according to this analysis. Strong winds out of the west in the Pacific have helped form this gyre, which is now centered over Nicaragua. Forecast models show heavy rain is expected across the region from Costa Rica to Jamaica to Mexico as the gyre slowly tracks northwest over the next ten to twelve days.
The question remains though, will there be tropical trouble for our region because of this gyre? The NBC2 First Alert Hurricane Tracking Team gives a feature on the east side of the gyre a 40% chance to develop through the weekend, but these odds will likely increase next week as conditions become more favorable.. As the gyre moves northwest this weekend it will run smack dab into strong wind shear which should keep anything from spinning up in the short term.
Next week the moisture and storm activity from this gyre will be entering the Gulf of Mexico and forecast models are indicating that wind shear may not be as strong. The water in the Gulf, as always, will be more than warm enough to fuel a system. However, it's just too far out and there are too many variables to know if all the pieces will come together for a named storm. Still, by this time next week, there's a decent chance we could be tracking a system in Gulf of Mexico, so make sure to keep a close eye on the forecast over the next several days.
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