Update: Invest 97L likely to become ‘Matthew’ later this week in the Caribbean Sea
MIAMI - A tropical disturbance, Invest 97L, well east of the Windward Islands, is now likely to develop into the next Atlantic tropical depression or storm within the next day or two, and may pose a threat into next week in the Caribbean basin and possibly beyond.
For now, this tropical disturbance is located about 700 miles east-southeast of the Windward Islands. It's a tropical "wave" because winds at the surface do not exhibit a closed low-pressure circulation, but rather shift from northeasterly ahead of the wave to southeasterly behind the wave.
The National Hurricane Center has tentatively scheduled the first Hurricane Hunter mission into Invest 97L for Tuesday afternoon.
First Stop: Windward Islands
Steered by the subtropical ridge of high pressure known as the Bermuda-Azores high, Invest 97L will arrive in the Windward Islands, bringing showers, some locally heavy rain and gusty winds beginning late Tuesday or Wednesday, according to our latest forecast.
The National Hurricane Center has given this system a high chance for formation into a tropical depression or storm over the next two days as it nears the Lesser Antilles into the Caribbean Sea. The next named storm in the Atlantic would be Matthew.
It should be noted this disturbance is starting out at a fairly low latitude, south of 10 degrees. Therefore, showers and gusty winds are expected in such locations as St. Vincent and the Grenadines, Grenada, Trinidad and Tobago, and perhaps even coastal Venezuela later this week.
By Thursday, the system, either still a tropical wave, depression, or Tropical Storm Matthew, will be in the eastern Caribbean Sea.
Again, given the potential for southern track, there could be rain and gusty winds in the typically drier "ABC Islands" – Aruba, Bonaire, and Curaçao – Thursday and Friday, perhaps lingering into Saturday.
Beyond that, uncertainty is high on this system's future.
There are currently west to northwest winds aloft over the Caribbean Sea, providing some wind shear, which is typically hostile to the development and intensification of tropical cyclones.
However, that wind shear is not much stronger than average for late September. Assuming the shear diminishes, the "future Matthew" may be able to intensify in the Caribbean Sea.
The reason that this tropical system has generated so much interest is model guidance has been indicating for several days that an intensifying tropical cyclone would be in the Caribbean Sea.
"The science tells us there’s no skill in seven-to-ten day forecasts of tropical systems that haven’t formed (like invests)."
Therefore, it's much too early to tell what other areas of the Caribbean Sea may be impacted by this system and whether any mainland U.S. locations will eventually be threatened.
Now is a good time to make sure you're prepared, before the storm.