Tropical Storm Danny Better Organized, May Become a Hurricane Later This Week; Potential Threat to Lesser Antilles Next Week

August 20,2015

• Tropical Storm Danny was located about 1,200 miles east of the Windward Islands in the eastern Atlantic Ocean as of 5 a.m. EDT Thursday.
• Maximum sustained winds remained at 50 mph with higher gusts.
• The tropical storm is forecast to gradually strengthen as it moves west-northwest over the next several days. Danny is forecast to become a hurricane later this week.
• It will be until early next week before Danny reaches the longitude of the Lesser Antilles.
• Danny is expected to weaken in the eastern Caribbean Sea.

Storm Stats and Satellite

Tropical Storm Danny continues to spin and hold its own, well to the east of the Lesser Antilles in the central Atlantic Ocean.

(MORE: Expert Analysis | Hurricane Central)

Microwave satellite imagery indicates Danny's convection looks to be more solidly organized around its center of circulation Thursday morning than it was Wednesday, notes hurricane specialist, Michael Lowry. 

(INTERACTIVE: Satellite Loop of Danny)

Water Vapor Image: Danny

Current Wind Shear Analysis

Small circulations such as Danny are prone to sudden changes in intensity, and this may be a sign Danny is finally on its long-anticipated strengthening.

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Dry air will be a continual challenge to Danny over the next several days, as water vapor imagery indicates an ample reservoir of dry air north of Danny extending westward into the Caribbean Sea.

Dry air hampers tropical cyclones by encouraging the development of stronger thunderstorm downdrafts, which then either squelch nearby thunderstorms from forming or push them away.

This dry air is also stable, meaning it suppresses upward vertical columns of air needed to maintain or form new thunderstorms.

Wind shear, namely, the change in wind speed with height either in speed and/or direction, can blow convection away from the center from a tropical cyclone. If strong enough, this can rip apart existing tropical cyclones.

Despite what had been a rather hostile atmosphere featuring record mid-July through mid-August Caribbean wind shear, Danny will remain far enough south over the next couple of days to remain in an environment of rather light wind shear.

So, assuming the atmosphere immediately surrounding Danny remains somewhat moist, Danny is forecast to strengthen to the first hurricane of the 2015 Atlantic hurricane season possibly as soon as Friday night or Saturday.

Danny will move generally toward the west-northwest the next several days. Computer model forecast guidance shows that it may not reach the longitude near the eastern Caribbean Sea (about 61 degrees West longitude) until Monday.

Projected Path

As a result, we have plenty of time to monitor its progress.
Given the aforementioned dry air and wind shear in place over the eastern Caribbean Sea, it's possible that this system will be weakening once it reaches the vicinity of the Lesser Antilles.
In summary, it's far too early to know if this system will bring any significant impacts to those islands in the long-term future. Interests in the Lesser Antilles, the Virgin Islands and Puerto Rico should monitor the progress of Danny.
(MORE: Satellite Maps)
Stay tuned to The Weather Channel and check back with weather.com for updates on this system.
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Senior meteorologists Nick Wiltgen and Jonathan Erdman and meteorologist Chris Dolce contributed to this report.

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