Sandy was stationary about 395 miles south-southwest of Kingston, Jamaica, the National Hurricane Center in Miami said in its 5 p.m. EDT advisory.
The storm packed maximum sustained winds of 40 miles per hour with higher gusts. Additional strengthening is expected, with the possibility of a hurricane warning for Jamaica by Monday night.
Sandy was expected to begin moving toward the north and north-northeast over the next couple of days, with the center reaching Jamaica by Wednesday.
Tropical storm-force winds extended 70 miles from the center. Jamaica, Haiti, the Dominican Republic and eastern Cuba could see 5 to 10 inches of rain from Sandy, with localized amounts reaching 16 inches. The rains could produce life-threatening flash floods and mudslides.
Meanwhile, Tropical Depression No. 19 developed over the central Atlantic Ocean Monday about 750 miles east-northeast of the Leeward Islands. The depression showed maximum sustained winds of 35 mph, and it could strengthen into a tropical storm by Monday night.