Florence could strengthen some over open water and then weaken as it nears land, but the difference won't make it any less risky, forecaster Stacy Stewart wrote in a National Hurricane Center discussion.
Florence's large size - tropical storm force winds extend 170 miles from the center in all directions - means its fury will arrive long before the center of the storm comes ashore, Graham said. The National Hurricane Center is calling for 20 to 30 inches (50 to 75 centimeters) of rain in North Carolina, with spots up to 40 inches (100 centimeters).
Jeff Byard of the US Federal Emergency Management Agency said it was imperative locals heed the evacuation warnings.
News that the storm could plow through SC after landfall came shortly after McMaster lifted his mandatory-evacuation order for Beaufort County and many other areas south of Charleston. Governors of those states have already declared states of emergency, as have the governors of Virginia and Maryland. In Myrtle Beach, S.C., and nearby areas, the surge could hit 6-9 feet.
North and SC residents are running out of time to evacuate before Hurricane Florence roars in with pounding surf and driving rain that will bring potentially deadly flooding, officials warn.
The storm is expected to hit the Carolinas hard later this week.
"They told me to bring a pillow and blanket", Whisler said. By late Wednesday, authorities in North Carolina reported almost 7,000 evacuees staying in 71 emergency shelters throughout the state.
Hurricane Florence makes landfall in Carolinas, threatens catastrophic flood
Hurricane-force winds extended 130 kilometres from its centre, and tropical-storm-force winds up to 315 kilometres. Ocean water flowed between homes and on to streets on the Outer Banks; waves crashed against wooden fishing piers.
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Forecasters said "catastrophic" freshwater flooding was expected along waterways far from the coast of the Carolinas. Roy Cooper said Friday that Florence is "wreaking havoc" and he's concerned "whole communities" could be wiped away.
Dominica prepares for passage of Hurricane Isaac
Isaac is forecast to gradually weaken over the next few days and could degenerate into a tropical wave at any time. Winds of 40 mph extend outward up to 115 miles (185 km) from the center of the tropical cyclone.
The Charleston International Airport will close Wednesday night at 11:59 p.m. until further notice, reports George Kearns of South Carolina Public Radio.
The New York Army National Guard is ready to deploy four helicopters - two CH-47 Chinooks and two UH-60 Blackhawks - to help storm response efforts.
As of 8:00 am (1200 GMT), it was packing sustained winds of 130 miles (210 kilometers) per hour, the Miami-based National Hurricane Center (NHC) said.
Masters said there's a tug-of-war between two clear skies high pressure systems - one off the coast and one over MI - and the more the Great Lakes one wins, the more southerly Florence will be.
Predictions now have the storm stalling and making a slight southward turn after it makes landfall.
The lingering storm could bring days of heavy rains, which could spark intense floods from SC to Virginia.
Moreover, high tides around noon and midnight these next few days will make the storm surges even worse, Samson said.
"We moved all the furniture up in case the water comes in but the water seems to be staying at the edge of the driveway", he said, adding that if the wind picks up and the rain keeps coming, that could change. "It's called Mother Nature".