(CNN) -- Officials in Bermuda urged residents to "prepare for the worst" as Hurricane Leslie headed toward the British territory, bringing with it powerful winds and heavy rain.
Meanwhile, the storm's effects were already being felt as far away as the U.S. East Coast, where forecasters issued warnings for life-threatening rip currents spawned by the distant storm.
In Bermuda, schools prepared to close Friday as residents got ready for the approaching storm.
"Leslie could be a historic storm for Bermuda as it is very large and forecast to intensify rapidly as it approaches," Bermuda's Emergency Measures Organization said in a statement. "The island could experience hurricane force winds for a sustained period of time, possibly up to two days."
The storm seemed to stall Thursday, moving just 10 miles (16 kilometers) since earlier in the day, the National Hurricane Center said. The storm was about 430 miles south-southeast of Bermuda, moving at 2 mph (3 kph), the center said.
It had maximum sustained winds of 75 mph (121 kph), the hurricane center said.
The storm wasn't expected to move much or significantly strengthen until Friday, the center said. Forecasters say it could affect Bermuda this weekend.
The storm is already dishing out heavy swells and dangerous currents in coastal areas of Bermuda, the Leeward Islands, Puerto Rico, the Virgin Islands and the U.S. East Coast from Florida to New York, the National Weather Service said Thursday.
Forecasters warned of potentially deadly rip currents that can pull even the strongest of swimmers out to sea quickly. The agency warned beachgoers to stay out of the surf until the danger passes.
Warnings were up in Florida, Virginia, Maryland, Delaware, New Jersey and New York.
The U.S. Coast Guard also warned boaters to use "extreme caution" through the weekend along the East Coast.
Another hurricane, Michael, formed late Wednesday in the eastern Atlantic. By early Thursday, it had become the first major hurricane of the season as it strengthened to a Category 3, with winds of near 115 mph.
Michael is the seventh hurricane of the 2012 season but posed no immediate threat to land, the hurricane center said.