MIAMI, Florida (CNN) -- Erika was drifting over the Leeward Islands Thursday morning, barely hanging on to her status as a tropical storm.
A tropical storm is a cyclone with maximum sustained winds between 39 mph (63 km/h) to 73 mph to (117 km/h), but Erika's winds were 40 mph (64 km/h), gusting to 50 mph (80 km/h), the National Hurricane Center said.
Erika could be downgraded to a tropical depression later Thursday morning, and approach the U.S. and British Virgin Islands and Puerto Rico later in the day, forecasters said.
At 8 a.m. ET, Erika was located 40 miles (64 km) southwest of St. Kitts and about 220 miles (350 km) east-southeast of San Juan, Puerto Rico. The storm was moving west-northwest at 7 mph (11 km/h). Parts of Puerto Rico could see as much as 8 inches (20 cm) of rain, with 3 (8 cm) to 5 inches (13 cm) elsewhere in the U.S. territory over the next few days, forecasters said.
A tropical storm warning was in effect for the Caribbean islands of Dominica, Guadeloupe, St. Martin, St. Barthelemy, Antigua, Barbuda, Montserrat, St. Kitts, Nevis, Anguilla, St. Maarten, Saba and St. Eustatius.
Tropical storm watches continued for Puerto Rico, the United States and the British Virgin Islands.
The barely tropical-storm force winds extended outward up to 230 miles (370 km) from Erika's center.
The Hurricane Center is describing Erika as "disorganized," because it has no well-defined center of closed circulation.
Erika is expected to start moving west-northwest later in the day and should pass over Puerto Rico Friday morning.
As it moves toward the Turks and Caicos Islands on Sunday, the storm is expected to dissipate, although heavy rain is still possible over the U.S. and British Virgin Islands through Friday evening.
Erika is expected to produce total rainfall accumulations of 2 inches (5 cm) to 4 inches (10 cm) over much of the Lesser Antilles.
-- CNN meteorologist Sean Morris contributed to this report.
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