A tropical storm has formed near Puerto Rico, the National Hurricane Center announced late Wednesday night. The storm, now known as Tropical Storm Isaias, spent much of the day lashing the eastern Caribbean with heavy rain.
The U.S. National Hurricane Center in Miami said the storm system was expected to pass south Puerto Rico on Wednesday night before making landfall in Hispaniola the following day on a path that could take it to the U.S. mainland by the weekend.
"I don't want people to lower their guards, because this system is quite dangerous," said Ernesto Morales with the U.S. National Weather Service in San Juan. "This is not (Hurricane) Maria, but it will bring a lot of rain."
President Donald Trump approved an emergency declaration request from Puerto Rico's governor, who also activated the National Guard.
As of 11 p.m. ET Wednesday, the storm system had maximum sustained winds of 50 mph. It was centered about 265 miles southeast of Santo Domingo, Dominican Republic, and was moving west-northwest at 20 mph.
The hurricane center said the system was expected to strengthen before it moved near or over the Dominican Republic on Thursday and eastern Cuba on Friday, although it cautioned that it was still unclear what it would do in upcoming days: "Simply put, there are a lot of hurdles in the system's way, so it is best to stay on the conservative side at the moment and continue to stress the large uncertainty after it leaves the Caribbean."
Forecasters issued tropical storm warnings for Puerto Rico, the British and U.S. Virgin Islands, St. Martin, St. Maarten, Saba, St. Eustatius, St. Barts, Turks and Caicos Islands and portions of Haiti, the Dominican Republic and the Bahamas. A tropical storm warning means that tropical storm conditions are expected within within 36 hours.
The forecast warned the islands could experience 3 to 6 inches of rainfall, with up to 10 inches in isolated spots.
Officials in Puerto Rico expressed concern about the potential for landslides and flooding and noted the U.S. territory is struggling with a spike inwhile also still recovering from 2017's and a earlier this year that damaged or destroyed hundreds of homes in the island's south.
Multiple power outages were reported across Puerto Rico on Wednesday night, with at least 96,000 customers without electricity. Puerto Rico's power grid was destroyed by Maria and the rebuilt system is fragile and susceptible to failures.
On Tuesday, the island's power company and union leaders said electricity failed for more than 450,000 customers when a plant was knocked offline for unknown reasons. On Wednesday, the director of Puerto Rico's Electric Power Authority told WKAQ radio that he believed it was either sabotage or negligence. However, the head of transmission and distribution disputed those comments and told Radio Isla that it was too soon to make any conclusions.
Officials said more than 300 shelters across the island were prepared to receive people if needed and that more than 130,000 face masks were available.