There were no immediate reports of any significant damage or injuries in the Caribbean islands as the center of the tropical storm churned toward the north-northwest at about 10 mph (17 kph). By late Sunday, it was about 225 miles (365 kilometers) north-northeast of San Juan, Puerto Rico, and was packing winds of roughly 65 mph (100 kph).
Forecasters at the U.S. National Hurricane Center in Miami said Rafael could strengthen into a hurricane by late Monday as it spins over the open Atlantic.
Rafael could then approach the wealthy British Atlantic territory of Bermuda late Tuesday. The Bermuda Weather Service issued a tropical storm watch for the storm-hardened territory of about 70,000 people late Sunday morning.
In the U.S. Virgin Islands, Elton Lewis, the territory's emergency management director, said authorities "don't anticipate any significant impact" from the passing storm. There were off-and-on showers during much of the day.
Tropical storm warnings have been discontinued for Caribbean islands. But the possibility of flooding and mudslides are still a concern in some islands, particularly in mountainous terrain, since Rafael has been forecast to dump between 4 to 8 inches of rain over the Lesser Antilles, small islands that include Dominica, Martinique and St. Lucia.
Rain ranging from 1 to 3 inches was expected in the U.S. Virgin Islands and the outlying Puerto Rican islands of Culebra and Vieques.
Swells generated by Rafael were expected to impact eastern-facing beaches of the Bahamas during the next few days. But forecasters said the storm's center will remain well east of the sprawling archipelago.