From The Weather Channel

Potential Threat to Lesser Antilles Next Week
Hurricane Danny has Formed in Atlantic
As Tropical Storm Danny continues to move [WEST], it is expected to become a hurricane, and is expected to reach the Caribbean by the first of next week.
Danny has strengthened into the first hurricane of the 2015 Atlantic hurricane season.
Hurricane Danny was located about 1,090 miles east of the Windward Islands in the eastern Atlantic Ocean as of 11 a.m. EDT Thursday.
Maximum sustained winds are now 75 mph with higher gusts.
Some additional strengthening is possible as Danny moves west-northwest over the next several days.
It will be until early next week before Danny reaches the longitude of the Lesser Antilles.
Danny is then expected to weaken in the eastern Caribbean Sea.
Hurricane Danny finally intensified Thursday morning into the first hurricane of the 2015 Atlantic hurricane season, well to the east of the Lesser Antilles in the central Atlantic Ocean.

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.

Stronger wind shear indicated by purple and red contours.
Danny’s hurricane-force winds extended up to only about 10 miles from the center of circulation as of the 11 a.m. advisory from the National Hurricane Center, a tiny hurricane-force wind field.

Small circulations such as Danny are prone to sudden changes in intensity, which can be difficult to forecast.

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 may remain a hurricane through this weekend.

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.

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, but may still be at least minimal hurricane strength upon arrival.

It remains too early to get too specific on impacts to those islands. Interests in the Lesser Antilles, the Virgin Islands and Puerto Rico should monitor the progress of Danny.

IMAGES:
Storm Stats and Satellite
Water Vapor Image: Danny Orange and red colors indicate dry air.
Current Wind Shear Analysis
Projected Path

Senior meteorologists Nick Wiltgen and Jonathan Erdman and meteorologist Chris Dolce contributed to this report.

For more on this story and video go to: http://www.weather.com/storms/hurricane/news/hurricane-danny-tropical-storm-danny-atlantic-2015

EDITOR: Two disturbances in Atlantic behind Danny.
From NHC

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT FRI AUG 21 2015
For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Hurricane
Danny, located over the central tropical Atlantic Ocean about a
thousand miles east-southeast of the Leeward Islands.

1. A broad non-tropical area of low pressure is located a couple
of hundred miles south of Bermuda. This system is interacting with
an upper-level low and is producing a large area of showers and
thunderstorms mainly to the east of the surface low. Environmental
conditions could support some tropical or subtropical development
while this system moves slowly northward over the western Atlantic
Ocean through the weekend.
* Formation chance through 48 hours…low…20 percent
* Formation chance through 5 days…medium…60 percent

2. A tropical wave located just off of the west coast of Africa is
producing disorganized showers and thunderstorms. Some slow
development of this system is possible during the next several days
while the wave moves westward at 15 to 20 mph over the eastern and
central tropical Atlantic.
* Formation chance through 48 hours…low…10 percent
* Formation chance through 5 days…low…30 percent

3. Another tropical wave is expected to move off the west coast of
Africa in a couple of days. Some development of this system is
possible early next week while it moves westward over the eastern
tropical Atlantic Ocean.
* Formation chance through 48 hours…low…near 0 percent
* Formation chance through 5 days…low…20 percent

Forecaster Beven

Additional images
NHC
http://www.tropicaltidbits.com/storminfo/04L_tracks_latest.png