Florence is expected to turn west and then north moving through the Carolinas and the Ohio Valley by Monday, the hurricane center said.
North Carolina Governor Roy Cooper told a news conference that the "historic" hurricane would unleash rains and floods that would inundate nearly the entire state in several feet of water.
Still, the storm has the capacity for huge destruction. Weather forecasters also warn that the threat of tornadoes is increasing as the system draws closer to land.
"Gradual weakening is forecast while Florence moves farther inland during the next couple of days, and it is expected to weaken to a tropical depression" by Saturday night, the center said in a bulletin.
The storm is moving in a northwesterly direction at about 9 km/h. The forecasters say the slow speed will give Florence time to pound the Carolinas with bands of heavy rain.
"A slow motion across portions of eastern and central SC is forecast Friday night through Saturday night".
Twice a day for the past week, Michael Sprayberry, the Director of North Carolina's Division of Emergency Management has briefed officials working out of the sprawling glass and steel building that is serving as the state's emergency response hub ahead of Hurricane Florence.
In Jacksonville, North Carolina, next to Camp Lejeune, firefighters and police fought wind and rain as they went door-to-door to pull dozens of people out of the Triangle Motor Inn after the structure began to crumble and the roof started to collapse.
The remainder of SC and North Carolina into southwest Virginia could see 6 to 12 inches, with some isolated areas seeing 15 inches.
On Thursday, Florence was a Category 3 hurricane on the five-step Saffir-Simpson scale with 120-mph winds (193 km). Parts of the Carolinas could see 50 cm to 76 cm, with isolated areas getting 101 cm, over seven days along the coast.
Florence is battering the North Carolina coast - flooding beach town roads from the Outer Banks to Carolina Beach.
According to meteorologists, Florence could be quite deadly-and with climate change making hurricanes more common and more catastrophic, there are going to be a lot more storms like Florence.
"Your time is running out", he warned.
Conditions are rapidly deteriorating along the coast of the Carolinas as Florence approaches.
Authorities typically say those who ignore evacuation orders are "on their own" should an emergency occur before first responders can be deployed. "Leaving is such a problem with the traffic going out", Jennie told VOA Thursday afternoon as she strolled along the shore of Carolina Beach near Wilmington, North Carolina.
"WE ARE COMING TO GET YOU", the city tweeted around 2 a.m. "Storms of this magnitude have struck the USA coastline in the past, in some cases causing $10 billion or less in total damage", Myers said.
In a new demonstration of the network's CGI capabilities, hosts have presented from the centre of a digital storm surge to demonstrate the hurricane's damaging potential.
At least 12,000 people have filled 126 shelters across the state.
Washington, DC, Mayor Muriel Bowser and the governors of North Carolina, South Carolina, Virginia, Georgia and Maryland have declared states of emergency. "There is overwash but nothing we are not used to", she said. "We're fully prepared. Food, medical, everything you can imagine, we are ready".