Invest 97L Likely to Become 'Matthew' Later This Week in the Caribbean Sea

Tom Moore and Jonathan Erdman
Published: September 26,2016
A tropical disturbance, Invest 97L, well east of the Windward Islands, is now likely to develop into the next Atlantic named storm later this week, and may pose a threat into next week in the Caribbean basin and possibly beyond.
(MORE: What is an Invest?)
For now, this tropical disturbance is located over 1100 miles east of the Lesser Antilles. 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.
(MORE: Why Tropical Waves Are Important in Hurricane Season)
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 by Wednesday, according to our latest forecast.

Five Day Possible Formation Area

The National Hurricane Center has given this system a high chance for formation into a tropical depression over the next 2 to 5 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, perhaps even coastal Venezuela later this week.
(MORE: Hurricane Central)

Caribbean Questions

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 far 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.

Current Satellite, Wind Shear

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.
(MORE: Just Because It's Fall Doesn't Mean We Shouldn't Pay Attention to the Tropics)
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.
However, as The Weather Channel hurricane expert, Michael Lowry eloquently put it in a recent blog post:

"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.
Since we have plenty of time to watch this system, check back with us at weather.com for the latest updates.
Now is a good time to make sure you're prepared, before the storm. Are you #HurricaneStrong?
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