At that point the storm was centered about 1,170 miles (1,880 km) east-southeast of Cape Fear, North Carolina, the NHC said.
North Carolina Governor Roy Cooper also urged his state's residents to get ready, noting the storm already was generating swelling waves and unsafe currents along the coast.
A National Hurricane Center graphic showing the potential track for Hurricane Florence, as of 11 a.m. The storm could impact anywhere from northern Florida to north of the Washington, D.C., area, producing life-threatening conditions.
In Virginia, mandatory evacuations begin 8 a.m. Tuesday for about 245,000 residents in a portion of Hampton Roads and the Eastern Shore area, Gov. Ralph Northam said Monday.
President Donald Trump declared an emergency in North Carolina, allowing it to access federal funds.
The governor urged residents to begin making their preparations as the entire SC coast remains in the cone of uncertainty.
Dare County officials ordered everyone to leave Hatteras Island on Monday.
Residents of coastal areas boarded up homes and packed their bags as they braced for Florence's wrath.
The farther south the center of Florence is able to move, the windier it will be here in central Georgia.
Tropical Storm Florence, now about 765 miles from Bermuda and 1,500 miles from the East Coast, is expected to regain strength and return to hurricane status later in the day Sunday.
Florence rapidly strengthened into a potentially catastrophic Category 4 hurricane Monday as it closed in on North and SC, carrying winds and water that could wreak havoc over a wide stretch of the eastern United States later this week.
Emergency Management Director Steven Still said tropical-storm-force winds were expected Wednesday.
Tropical Depression Nine formed 1755 miles east of the Windward Islands Friday.
The hurricane center says Isaac is a very small hurricane and its intensity could fluctuate as it approaches the Caribbean. "That is a sign of a strengthening hurricane".
Tropical Storm Helene is just off the African coast and tropical storm warnings have been issued for the southern Cabo Verde Islands.
Still said it been "quite some time" since a storm of Florence's magnitude had approached Southeastern North Carolina.
As state agencies prepare, residents are advised to prepare for impacts from this storm.
If a major hurricane (Category 3 or higher) does make landfall along the southeast coast, the rarity of such an event is relevant.
Forecasters said it was too soon to tell where the storm would go. After the current round of storms, though, long-range models suggest a lull for several weeks.
Swells generated by Florence were affecting Bermuda and starting to reach parts of the U.S. East Coast. Meteorologists expect the tropical storm to evolve into a major hurricane by Tuesday night. People in coastal communities are taking all precautions.
The second week of September is the peak of hurricane season, so the flurry of activity is no surprise to forecasters.
The hurricane's path was still far from certain Monday. "10.html">the school said in a statement posted online.
The National Hurricane Center classified tropical storm Florence as a Category 1 hurricane, Sunday, warning that it would rapidly intensify into a major hurricane by Monday and could make the Thursday landfall as a Category 4 "extremely risky major hurricane". Florence, because of its weaker state, has been moving along toward the west.
The storm is forecast to move generally in a westward direction over the coming days, with an increase in forward speed during the early part of the week.
It would be the first Category 4 hurricane to do so since Hugo in 1989.
Forecasters said Florence was expected to become an extremely risky major hurricane sometime Monday, and remain that way for days.
Hurricane Isaac is holding steady in strength over the Atlantic.
The storm reached major hurricane status Wednesday, peaking with maximum sustained winds of 130 miles per hour. The storm was moving west at 13 miles per hour (20 kmh). NOAA NWS National Hurricane Center/Handout via REUTERSA photo taken from the International Space Station by astronaut Ricky Arnold shows Hurricane Florence over the Atlantic Ocean in the early morning hours of September 6, 2018.