MIAMI (CBSMiami) — Tropical Storm Rafael strengthened Saturday as it continued north across the eastern Carribean.

At 8 p.m. Saturday, the storm was 25 west-southwest of St. Martin, or 85 miles east of St. Croix. Rafael had top sustained winds of 50 mph and the storm was moving north at 12 mph.

Some strengthening is forecast during the next 48 hours, and Rafael could become a hurricane by late Monday. Rafael is expected to return to a north-northwest track on Sunday.

Tropical-storm-force winds can be expected across Puerto Rico overnight and into Sunday.

Rafael is expected to produce total rainfall amounts of 3 to 5 inches, with isolated totals of 10 inches, over the Lesser Antilles, the Virgin Islands, Culebra and Vieques.

A Tropical Storm Warning is in effect for the Culebra, Vieques, the U.S. Virgin Islands, the British Virgin Islands, Anguilla, Barbuda, St. Kitts, Nevis, Antigua, Montserrat, Saba, St. Eustatius, St. Maarten, St. Martin, Guadeloupe, Desirade, Les Saintes and Marie Galante. The warning means tropical storm conditions are expected within the warning area…in this case within 12 to 24 hours.

A Tropical Storm Watch is in effect for Puerto Rico. This means that tropical storm conditions are possible within the watch area.

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