NHC has begun issuing advisories on Potential Tropical Cyclone Eighteen. It’s located over the Northwest Caribbean Sea about 305 miles (490 km) south-southwest of the Isle of Youth and about 415 miles (670 km) south-southwest of Havana, Cuba.

A Tropical Storm Warning is in effect for Isla de la Juventud, La Habana, Ciudad de la Habana, Matanzas, Cienfuegos, and Villa Clara, and the Northwestern Bahamas. A Tropical Storm Watch is in effect for the Central Bahamas. Tropical storm conditions are expected to first reach the warning area in Cuba Saturday and the northwestern Bahamas Saturday night. Interests in the Cayman Islands, South Florida, and the Florida Keys should monitor the progress of this system.

On the forecast track, the system will move across western Cuba late Saturday and move through then northwestern Bahamas Saturday night and early Sunday. Data from an Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds are near 40 mph (65 km/h) with higher gusts. However, the system does not yet have a well-defined center. Some strengthening is forecast during the next 24 to 36 hours. Environmental conditions are expected to be conducive for development, and the system is likely to become a tropical storm tonight or Saturday. When that occurs, it will be given the name “Philippe”.

The system has the potential to produce the following rainfall totals:
– Northern Honduras: Additional 1 to 3 inches tonight.
– Cayman Islands, western and central Cuba and the Northwest
Bahamas: 4 to 8 inches with maximum totals of 10 inches.
These rainfall amounts may produce life threatening flash floods and mudslides.
– South Florida, including the Florida Keys: 3 to 5 inches, with isolated maximum of 8 inches possible. These rainfall totals may produce flash flooding, especially in urbanized areas.