Updated at 2:30 p.m. ET
Puerto Rico and parts of the Dominican Republic are now under a hurricane watch because of Tropical Storm Dorian, meaning those places could see dangerous conditions within 48 hours.
Dorian's maximum sustained winds weakened to 50 mph from 60 mph overnight, according to the National Hurricane Center. As of 2 p.m. ET, the compact storm was about 70 miles west-northwest of Martinique, after crossing into the eastern Caribbean Sea on Tuesday morning.
"Slow strengthening is forecast during the next 48 hours," the NHC says, "and Dorian is forecast to be near hurricane strength when it moves close to Puerto Rico and eastern Hispaniola."
Dry air around Dorian has tamped down the storm's strength. And the hurricane center says the system could also weaken substantially when it passes over large land masses in Puerto Rico and Hispaniola.
Questions remain about what Dorian might do after that point, but it seems likely that the storm will persist as it moves to the northwest, toward the U.S. mainland.
"The threat of winds and heavy rains later this week into this weekend in the Turks and Caicos, the Bahamas, and Florida is increasing," the National Hurricane Center says. It predicts that the storm's center will move near the Turks on Thursday night.
In its latest forecasts on Tuesday morning, the hurricane center says Dorian's winds are likely to weaken but then strengthen somewhat over the next four days. Its sustained winds are expected to top 70 mph shortly after passing over Puerto Rico.
The current forecast calls for Dorian to reach Florida's southeastern coast in the early hours of Sunday morning.
Despite maintaining a compact, roughly circular shape, Dorian has not developed a well-defined core. It began the day Tuesday as it did Monday, with tropical-storm-force winds that extend outward for only 45 miles from the center.
Dorian passed by Barbados late Monday night, apparently without causing any severe damage or injury. The island announced an all-clear at 5 a.m. local time.
"We need to give thanks," Prime Minister Mia Amor Mottley said at a news conference, noting that "from all reports, there is virtually no damage."
Fewer than 10 weather-related incidents were reported on Barbados as of Tuesday morning, Mottley said, and those cases mainly involved fallen trees. While noting that there was inclement weather, she added, "it's the kind of inclement weather we're accustomed to."
Early Tuesday, St. Lucia discontinued its tropical storm warning, though it did not lift a mandatory shutdown order.
Dorian isn't likely to strengthen into the sort of fearsome cyclones that recently ravaged Puerto Rico and other islands, but it still poses a threat to vulnerable areas because of heavy rains and high winds. It's expected to drop 2 to 4 inches of rain in Puerto Rico, St. Croix and the Dominican Republic, with 6 inches of rain possible in isolated spots.
"Flooding and landslides are likely during this storm," the government of St. Lucia said around midnight Tuesday. The island remained under a national shutdown until 10 a.m. local time, when it announced an all-clear.