Tropical Storm Matthew Strengthening in the Eastern Caribbean; Warnings Issued in Windward Islands

September 28,2016
Tropical Storm Matthew is now heading for the central Caribbean Sea and is forecast to strengthen into a hurricane, posing a threat to parts of the Caribbean basin and possibly parts of the U.S. later next week. Matthew was the 13th named storm of the 2016 Atlantic hurricane season.
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Matthew was located over 350 miles south-southeast of San Juan, Puerto Rico, as of Wednesday night.

Current Storm Status

On Wednesday morning, a Hurricane Hunter reconnaissance mission found a sufficient low-level circulation to upgrade the former Invest 97L into a tropical storm, based on flight-level winds measured over 60 mph.
Tropical storm conditions will continue across portions of the Windward Islands into early Thursday morning.
A wind gust to 89 mph was reported in St. Pierre, Martinique, Wednesday evening. Some stations are elevated at 50 to 100 feet. Sustained winds of 39 mph were reported on the island of Barbados.

Tropical storm warnings have been issued for parts of the Lesser Antilles, including Guadeloupe, Martinique, St. Lucia, Dominica, St. Vincent and the Grenadine Islands. Winds over 40 mph are likely there into early Thursday morning.
Tropical storm watches have been issued for Aruba, Bonaire, and Curaçao. Winds of 40 mph or greater are possible there within 36 to 48 hours.

Current Watches/Warnings

Rainfall accumulations of 4 to 8 inches are expected across the Windward Islands and the southern Leeward Islands through Thursday. Life-threatening flash flooding is possible.
Rainfall of 1 to 2 inches can be expected farther north across the northern Leeward Islands plus the Virgin Islands and Puerto Rico.
Accumulations will range from 1 to 3 inches across the Leeward Antilles, including Aruba, Bonaire and Curaçao through Friday.

Caribbean Questions

Given the southern track, there could be some outer bands of rain and gusty winds in the typically drier "ABC Islands" – Aruba, Bonaire and Curaçao – as well as parts of coastal Venezuela and Colombia Thursday through early Saturday.
Beyond that, uncertainty is still considerable on the critical details of this system.
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Over the next couple of days, Matthew should continue to move toward the west or just a smidge north of west as it rides the southern periphery of the Bermuda High westward.
In general, ensemble forecast guidance suggests Matthew should make a northwest or even northward turn in the Caribbean Sea sometime this weekend, as the system reaches the southwestern edge of the Bermuda high.

Projected Path and Intensity

Matthew could then threaten Hispañola, Jamaica or parts of eastern Cuba as soon as early next week, likely as a hurricane.

U.S. Threat?

Beyond that, it is far too soon to determine which parts of the U.S. may be in danger.
Ensemble forecast guidance includes scenarios where Matthew moves north, then northeast remaining well off the East Coast, but also includes tracks into the Gulf of Mexico next week.
(MORE: Why Long-Range Model Forecasts For the Tropics Can't Often Be Trusted)
The track will depend, in part, on the steering currents in the atmosphere.

• If high pressure aloft is stronger near or over the Eastern U.S., that may steer Matthew closer to some part of the U.S.
   
• Conversely, if a southward dip in the jet stream is in play over some part of the Eastern U.S., that could help deflect Matthew to the east.

For now, it appears the majority of our ensemble guidance has some form of high pressure aloft over some part of the East next week, implying a land threat for at least part of the U.S. coast.
There is also considerable uncertainty on how fast Matthew moves.
It's also worth noting interaction with land, including mountainous terrain in the Caribbean may also play a role in this system's future.
Colorado State University tropical scientist, Dr. Phil Klotzbach noted 60 percent of landfalling U.S. hurricanes from September 27 and beyond since 1900 have occurred in Florida. However, while lower probability, there have been landfalls this late in the season as far west as the Texas Gulf Coast.

Typical October named storm origin locations and tracks.

For now, all interests in the Caribbean Sea, Gulf of Mexico, Bahamas and U.S. East Coast should monitor the progress of Matthew. Check back with us frequently at weather.com for any important forecast updates.
Now is a good time to make sure you're prepared before the storm. Are you #HurricaneStrong?
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