A tropical storm warning, indicating the expectation of conditions below hurricane-strength winds, is in effect for coastal areas north of the Virginia border to Cape Charles Light, Va., and in Chesapeake Bay, south of New Point Comfort, Va.
The NHC said Florence is expected to be an "extremely unsafe major hurricane" when it makes landfall in the Carolinas late Thursday or early Friday, bringing life-threatening storm surge to coastal areas.
It is expected approach the North Carolina coast late Thursday night as a powerful and destructive hurricane.
The Carolinas, Virginia, Maryland, and Washington DC have all declared states of emergency.
Residents prepared by boarding up their homes and stocking up on food, water and other essentials, stripping grocery store shelves of merchandise.
"You're going to get heavy rain, catastrophic life-threatening storm surge, and also the winds", Graham said. Electricity supplies are also expected to be threatened by the wind.
"That's the million dollar question and, right now, we just don't have an answer to it", he said.
The last hurricane rated a Category 4 on the five-step Saffir-Simpson to plow directly into North Carolina was Hazel in 1954, a devastating storm that killed 19 people.
McMaster has already declared a state of emergency in SC and asked President Donald Trump for a federal declaration ahead of the storm, which intensified Monday to a potentially catastrophic Category 4 hurricane with maximum sustained winds near 130 miles per hour (195 kph). Jeff Byard of the Federal Emergency Management Agency (FEMA) invoked a former boxing champion to warn residents that it would bring "a Mike Tyson punch to the Carolina coast".
U.S. President Donald Trump on Twitter warned of the storm's dangers and praised his administration's handling of past hurricanes, rejecting criticism for its response to Hurricane Maria a year ago in Puerto Rico.
President Donald Trump has insisted that the government is "absolutely, totally prepared" for the arrival of the hurricane.
All of this means that, in addition to very strong winds and storm surge beginning Thursday along the Carolina coasts, the southeastern United States will have to prepare for a major, and perhaps historic, flooding event. Over the weekend, authorities undertook more than two dozen rescues at Wrightsville Beach in North Carolina.
Airlines are beginning to cancel flights ahead of the hurricane.
However, recent trends in the forecast models now indicate a rare-if not unprecedented for an Atlantic hurricane this far north and west-turn to the southwest before Florence resumes its west-northwest motion.
Southwest Airlines said travelers booked to fly from six cities from Baltimore to SC can rebook their flights within 14 days of their original dates with no additional cost.
The coastal surge from Florence could leave the eastern tip of North Carolina under more than 9 foot of water in spots, projections showed.
These are worrying times for the east coast of America.
"This will be a storm that creates and causes massive damage to our country".
"You are talking about the entire ocean level rising up as a storm of this size makes landfall", Barnes said. Any structures that are in the path of this surge will be damaged, if not completely destroyed.
"The current forecast for both the impact and aftermath of the hurricane would require those officials to divert critical resources from what could be much more significant duties", UNC athletics director Bubba Cunningham said in a statement.