Tropical Storm Sandy a threat to Jamaica, Cuba, Haiti

Tropical Storm Sandy, strengthening rapidly Monday in the warm waters of the Caribbean Sea, was expected to bring heavy rains to Jamaica, Cuba and Haiti over the next few days.

The National Hurricane Center predicted Sandy would remain well off the coast of Florida, but the state and much of the East Coast potentially could still feel ripple effects of gusty winds and pounding surf as the storm passes by far offshore.

Both Jamaica and Haiti were placed under tropical storm warnings for Sandy, the 18th named storm of the 2012 Atlantic hurricane season. At 5 p.m., the storm was drifting about 400 miles southeast of Kingston, with maximum sustained winds of 40 mph.

Forecasters expected the storm to run into stronger wind shear in a few days, which could keep it just below hurricane strength as it approaches Jamaica on Wednesday morning. It was still a potentially dangerous storm for island countries, particularly Haiti, which are prone to deadly flooding and mudslides. Forecasters said rainfall could average from five to 10 inches, and reach 16 inches in isolated spots.

NHC spokesman Dennis Feltgen said computer models were in good agreement that high-pressure systems to the north and west would begin to steer Sandy to the north and northeast across Jamaica and eastern Cuba before emerging into the Southern Bahamas by Friday. That “squeeze’’ between pressure systems, not Sandy itself, also could generate strong winds and waves across South Florida in coming days.

Another depression also formed in the far-off Atlantic on Monday. Forecasters expected it to strengthen into Tropical Storm Tony over the next few days but said it did not pose a threat to land. The hurricane season ends Nov. 30.