Forecasters watching for rare March subtropical storm near Puerto Rico

Caribbean satellite

An area of disturbed weather north of Puerto Rico may develop into a subtropical system early next week. (Credit: NOAA)

Off-season Hurricane Alex surprised weather watchers with an appearance in January 2016. Now, a named Atlantic system may pop up on the map in the waning days of March.

Saturday runs of the major forecast models, including NOAA’s GFS, the European (ECMWF) and the Canadian show a tropical or subtropical system spinning up just north of Puerto Rico late Sunday and into Monday. They move the system to the northwest before taking it east out into the open Atlantic toward mid-week.

If anything tropical or subtropical does develop beyond depression status it would get the name Arlene.

The GFS has the low cranking up to a 997 mb storm east of Bermuda while the European is a bit more aggressive with a 984 mb low on the map by Thursday. That would usually translate to a fairly strong subtropical storm or even a system close to hurricane strength.

The Canadian takes it down to a 982 mb system — with all forecasts well out into the Central Atlantic.

At Weather Underground, however, Category 6 bloggers Jeff Masters and Bob Henson say 75-degree water temperatures east of the Bahamas are “barely warm enough to support formation of a subtropical depression or subtropical storm.”

“We give five-day odds of 10 percent of this low becoming a subtropical depression or subtropical storm,” they said Friday.

March cyclones are so rare that only one has ever formed in recorded history — a Category 2 hurricane in the Caribbean that reached peak wind speed of 100 mph on March 8, 1908. It battered the U.S. Virgin Islands before losing its punch in the Caribbean on March 9.

The hurricane began as a low pressure system northeast of the islands and moved in a south-southwesterly direction while intensifying.

A second off-season hurricane formed in May of that year and came within about 100 miles of Florida’s East Coast. That storm formed north of Hispaniola on May 24 and moved northwest just east of the Bahamas at tropical storm strength. It turned north-northeast well east of Daytona Beach.

It hit eastern Long Island, New York with winds of 40 mph on May 30 and made landfall on the coast of Connecticut.

The hurricane season officially runs from June 1 to November 30. As of Saturday the season was still 67 days away.


Author: jnelander

Freelance writer and editor

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