Tropical Storm Dorian spun directly over St. Lucia on Tuesday, dropping rain and gusting winds as it heads through the eastern Caribbean Sea toward Puerto Rico.
The storm is expected to strengthen over the next 24 hours, and the threat of winds and heavy rains reaching Florida this weekend is increasing, the National Hurricane Center said.
Florida residents "should monitor the progress of Dorian and ensure that they have their hurricane plan in place," the weather service said Tuesday.
Puerto Rico was under a hurricane watch Tuesday. At 11 p.m. EDT, the storm was about 275 miles east-southeast of Ponce, Puerto Rico, with maximum sustained winds around 50 mph.
Forecasters expected Dorian to continue moving northwest and pass over or near Puerto Rico on Wednesday. The storm could strengthen to bring hurricane conditions to the U.S. territory.
Four to 6 inches of rainfall are forecast for Puerto Rico and the Dominican Republic; isolated areas could get up to 8 inches. Martinique to St. Vincent could see 3 to 6 inches of rain, and the U.S. Virgin Islands may get 1 to 3 inches, forecasters said.
The hurricane center warned that the rains could cause "life-threatening flash floods."
However, the storm's interaction with the land masses of the Caribbean islands make it hard to predict how strong it will be if it roars north toward the Turks and Caicos and the Bahamas – and eventually Florida.
By Wednesday, it should be clearer how Dorian will run the gauntlet in the Caribbean, said Ryan Truchelut, chief meteorologist at WeatherTiger.
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Dorian is a small storm, and the dry air now surrounding it and the wind shear that tend to tear storms apart will affect how Dorian develops, Truchelut said. He said there's a 30% chance the storm dissipates over the eastern or central Caribbean in the coming days.
It could slip by Hispaniola without major disruption, however, which would bring a stronger storm near the Bahamas. That could mean the storm shifting west toward Florida on Friday and Saturday.
In that case, Dorian would be a stronger tropical storm or hurricane in the vicinity of the Bahamas to start the weekend. Truchelut gave that scenario a 40% chance of developing.
Dorian dumped heavy rain on the Windward Islands on Tuesday. In Barbados, crews were clearing downed trees, and much of the island's northern region was without power, Jackie Marshall-Clarke, a spokeswoman for Barbados Light & Power, said on state-owned TV.
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Cruise lines sailing out of Port Canaveral, Florida, started rerouting their ships from the eastern to the western Caribbean to avoid the storm.
Residents of Puerto Rico, where about 30,000 homes with blue tarps provide a reminder of the devastation caused by Hurricane Maria nearly two years ago, lined up at stores to stock up on supplies such as food, generators and bottled water.
Puerto Rico Gov. Wanda Vázquez on Monday declared a state of emergency and provided a list of all the new equipment that public agencies have bought since Hurricane Maria.
"I want everyone to feel calm," she said. "Agency directors have prepared for the last two years. The experience of Maria has been a great lesson for everyone."
Public schools closed Tuesday afternoon, and the island's 360 shelters will remain opened for those without proper roofs, she said.
Florida Gov. Rob DeSantis said on Twitter that he was briefed by Florida Division of Emergency Management and is working to ensure that the state is ready for harsh conditions brought by Dorian.
He encouraged residents to prepare by securing at least a week's worth of food, water and medicine.
Based on the current track of #TropicalStormDorian, all residents on the East Coast should prepare for impacts, including strong winds, heavy rain and flooding. Make sure to have your supplies ready and follow @FLSERT and local media for the latest updates on the forecast.
— Ron DeSantis (@GovRonDeSantis) August 27, 2019
Barbara Behrens, 67, has lived in South Florida for more than two decades. She's seen hurricanes that have forced her to evacuate, and more tropical storms than she can count.
She's trying to stay informed on Dorian's whereabouts but so far, she said, she isn't very concerned.
"We've been through so many," Behrens said, "this doesn't look all that bad."
Hurricane prep feels almost routine to her now, Behrens said. "You get tired of it."
But it doesn't make her want to move away from South Florida. She used to live in fear of tornados in Ohio — and would often get no warning before one hit. At least with hurricanes and tropical storms, Behrens said, residents are warned in enough time to prepare.
Contributing: Olivia Sanchez, Cheryl McCloud and Doyle Rice; The Associated Press. Follow Ryan Miller on Twitter: @RyanW_Miller
This article originally appeared on USA TODAY: Dorian: Tropical storm forecast to hurl toward Caribbean islands