Tropical depression Fred was slowly strengthening and could regain tropical storm status sometime on Friday, forecasters said.
The system was dropping heavy rain over parts of Cuba in the early morning hours and was on a forecast track that would carry it toward South Florida by Saturday, the U.S. National Weather Service said.
The main threats were rain and flooding. Forecasters issued a tropical storm watch Thursday evening for the Florida Keys and the state’s southwest coast. The hurricane center said 3 to 6 inches (7.5 to 15 centimeters) of rain were expected across the Florida Keys and southern peninsula by Monday, with isolated maximums of 8 inches (20 centimeters).
The tropical storm watch also included the Cuban provinces of Ciego de Avila, Camaguey, Las Tunas, Holguin and Granma.
Once a tropical storm, Fred weakened back to a depression by its spin over Haiti and the Dominican Republic where it knocked out power to some 400,000 customers and caused flooding that forced officials to shut down part of the country's aqueduct system, interrupting water service for hundreds of thousands of people.
Local officials reported hundreds of people were evacuated and some buildings were damaged. There were no immediate reports of casualties.
Heavy rains on Thursday continued to pound Hispaniola which the two nations share.
The Miami-based U.S. hurricane center said Fred had maximum sustained winds of 35 mph (55 kph) Friday morning and was centered just north of Cuba's coast.
The system was about 410 miles (660 kilometers) east-southeast of Key West, Florida. That was also about 165 miles (265 kilometers) southeast of Southern Andros Island in the Bahamas.
Fred was headed west-northwest at 9 mph (15 kph).
The system was expected to produce 3 to 5 inches (7.5 to 12.5 centimeters) of rain across the Dominican Republic and the western Bahamas, as well as 1 to 3 inches (2.5 to 7.5 centimeters) over Haiti, the Turks and Caicos, the eastern Bahamas, and Cuba.
Fred became the sixth named storm of the Atlantic hurricane season late Tuesday as it moved past the U.S. Virgin Islands and Puerto Rico.
