Tropical Storm Sandy formed in the western Caribbean Sea on Monday and put Jamaica, Cuba and Haiti on alert for severe weather over the next few days, the U.S. National Hurricane Center said.
The storm was centered about 395 miles (640 km) south-southwest of Kingston, Jamaica, and had top sustained winds of 40 miles per hour (65 kph).
The storm did not pose a threat to the Gulf of Mexico, where U.S. oil and gas operations are clustered.
A tropical storm watch was in effect for both Jamaica and Haiti, meaning residents should expect heavy rains and strong winds within 48 hours.
Computer models showed Sandy was expected to remain a tropical storm on a projected path that would carry it over Jamaica on Wednesday and then eastern Cuba and the Bahamas.
Sandy is expected to dump as much as 5 to 10 inches (12.5-25 cm) of rain across parts of Jamaica, Haiti, the Dominican Republic and eastern Cuba, forecasters said.