'Little change was expected in the storm's strength in the next couple of days'
Isaias, downgraded from a hurricane but still a powerful tropical storm, churned close to Florida on Sunday, set to brush the state's east coast with strong winds, drenching rain and potential coastal flooding.
By 1200 GMT, Tropical Storm Isaias was about 70km east-southeast of West Palm Beach, heading northwest with top sustained winds of 100 kph per hour, the National Hurricane Centre (NHC) said.
On its current path, Isaias will move near or over Florida's east coast during Sunday, the Miami-based NHC said. On Monday and Tuesday, its centre would move from offshore of the coast of Georgia into the southern mid-Atlantic states.
Little change was expected in the storm's strength in the next couple of days, the NHC said.
Parts of the US East Coast from south Florida to Cape Fear in North Carolina could be hit by storm surges - when a storm pushes tidal levels above normal - of up to 4ft, the NHC said.
Rainfall could total as much as 6 inches in parts of Florida.
Isaias was not expected to affect the return home on Sunday of two Nasa astronauts who rode to the International Space Station aboard SpaceX's new Crew Dragon.
They were heading for a splashdown in the Gulf of Mexico, off Florida's northwest coast, capping a two-month voyage in space that marked Nasa's first crewed mission from home soil in nine years.
The storm is heading to Florida at a time when the state is grappling with one of the country's worst coronavirus outbreaks.
Isaias lashed parts of the Bahamas with what was expected to be as much as 1ft of rain en route to the United States.
It caused at least two deaths in the Dominican Republic and knocked out power for thousands of homes and businesses in Puerto Rico, according to media reports.