MIAMI — Tropical Depression Eighteen has formed in the eastern Atlantic Ocean and will become a hurricane by this weekend. However, it’s uncertain whether it will strike the Leeward Islands next week.
This new system is about 2,000 miles east-southeast of the northern Leeward Islands in the eastern Atlantic Ocean and is moving west around 15 mph.
Satellite-based wind data Wednesday found a low-level circulation had developed and thunderstorms had persisted to allow it to be classified as a tropical depression by the National Hurricane Center.
Once its maximum sustained winds reach 40 mph, it will become Tropical Storm Sam, the eighteenth named storm of the 2021 Atlantic hurricane season. It currently has maximum sustained winds of 35 mph.
An Uncertain Future For Leeward Islands
It’s not yet clear if Sam will ever threaten land, but it will take its time.
According to the latest computer forecast models, Sam may not reach the longitude of the Lesser Antilles until the middle of next week.
Whether it passes over parts of the islands or bypasses them to the north is unclear, at this time.
Beyond that, the large majority of computer model forecasts eventually curl Sam away from the U.S. East Coast late next week.
That’s because they’re forecasting a weaker, less expansive Bermuda high over the Atlantic Ocean and a stronger trough, or southward plunge of the jet stream, near the East Coast, as described in a previous article here.
That pattern would cause Sam to curl north, then northeastward into the central Atlantic Ocean, rather than simply plowing westward.
However, it’s far too soon to completely rule out Sam as a potential U.S. threat.
Sam Could Become a Strong Hurricane
What is of higher confidence is that Sam will have an environment conducive for intensification into at least early next week, including low wind shear and increasingly warm water.
In this environment, Sam will likely become a hurricane by this weekend east of the Lesser Antilles, and could become a stronger hurricane by early next week.
Sam will be the second earliest “S” storm in Atlantic Basin history, behind only 2020’s Sally, according to NHC hurricane specialist Philippe Papin.
