"McMaster said he would reverse lanes on four main roads to facilitate the evacuation", The State reported.
Horry County will have two four-lane reversals along US 501 - from S.C. 544 to USA 378, and between S.C. 22 and S.C. 576 near Marion County.
The US military said it was sending an advanced team to Raleigh, North Carolina, to coordinate with federal and state partners and that about 750 military personnel will be set aside to provide support. Among the airports commonly mentioned are those in North and SC, as well as Norfolk and Richmond, VA and Savannah, GA. The president has spoken to the governors of both Carolinas and Virginia, the White House said Monday. The Carolina coast needs to brace for impact Thursday and Friday. "We will experience a significant and sustained rainfall event with flooding".
Evacuation shelter locations for those evacuating from the state's northern and central coastal counties will be available on scemd.org, McMaster said.
"Currently, the bulk of the rain is forecast to occur across eastern North Carolina and some places over 10 inches but if the track slows down or is just to the left then those high rain totals could cover a large portion of southeastern North Carolina versus staying to our north", said Pfaff.
S.C. Rep. Alan Clemmons, R-Horry, tweeted Monday afternoon that McMaster had told legislators he would order evacuations for the coast beginning at noon Tuesday.
The National Hurricane Center is calling the storm "extremely risky", and predicts it could still strengthen to near Category 5 intensity on Tuesday. It could potentially become the "Harvey of the East Coast".
The hurricane will weaken slightly before it makes landfall on Thursday as it encounters more wind shear, but Florence should still be a major hurricane at landfall along the central North Carolina coast.
Because Florence is expected to stall after landfall, the rain is forecast to hit the same area for a long period of time.
Hurricane watches and storm surge watches are expected to be issued Tuesday morning ahead of the arrival of Florence.
Florence was more than 400 miles wide early Monday, according to the NWS.
He wrote: "My people just informed me that this is one of the worst storms to hit the East Coast in many years".
To whip up a monstrous storm like the one chugging for the Carolinas you need a handful of ingredients - and Florence has them all.
State emergencies have already been declared in North Carolina, South Carolina, Virginia and Maryland.
The South Carolina National Guard also was called out to assist.
At 5 a.m. today, the storm was located 975 miles from Wilmington and was moving west-northwest at 15 mph at maximum sustained winds of 140 mph. Gen. Robert E. Livingston Jr., head of the National Guard.
The Transportation Department also has more than 3,000 employees ready to deploy, and more than 440 additional state law enforcement officers have been moved to the coast. Myrtle Beach Mayor Brenda Bethune urged people to secure their homes but said it was too early to know if evacuations will be ordered.