To whip up a monstrous storm like the one chugging for the Carolinas you need a handful of ingredients - and Florence has them all. "This is a storm that is historic, maybe once in a lifetime".
The eastbound lanes of several major highways have been shut down to allow for a smooth flow of traffic inland.
The federal government has made similar warnings, with FEMA Administrator Brock Long saying Florence could knock out power for "weeks".
The slow-moving storm, the most severe hurricane to threaten the US mainland this year, was located about 785 miles (1,260 km) southeast of Cape Fear, North Carolina, at 4:30 p.m. EDT (2030 GMT), according to the NHC.
"We'll be asking people to prepare their emergency kit", he said.
Here's the latest on the storms projected path and when and where it will make landfall.
Meanwhile, the projections for rain are growing, adding to growing concerns about flooding across the two states: Coastal North Carolina now expects 20 to 30 inches, with isolated areas of 40 inches projected in SC. That includes growth ringing metro areas such as Myrtle Beach and Wilmington on the coast and Raleigh-Durham inland.
"This storm is going to be a direct hit". The storm will likely dump between 20 and 30 inches (50 to 76 centimeters) of rain over its track, causing serious flooding.
"Re-strengthening is forecast to occur during the next day or so, and Florence is expected to be an extremely unsafe major hurricane through Thursday night", said the National Hurricane Center in its latest update.
One million asked to evacuate as Hurricane Florence closes in
The last time the USA capital declared a state of emergency was in January 2016 when a winter storm dubbed "Snowzilla" blanketed the capital region in knee-deep snow.
This story will be updated as more information is available regarding the reopening of schools. She grew up on the island chain, and says this will be only the second time she's evacuated.
"I'm telling them to go inland, but I'm anxious about the rain and tornadoes too", Roberts said.
Hurricane warning: South Santee River South Carolina to Duck, North Carolina and Albemarle and Pamlico sounds. "Not anxious in the least".
"I've been doing this since 1983", Roberts said as he completed an order for another 18-wheeler full of supplies.
Officials have called for the mandatory evacuation of more than 1.4 million coastal residents across the Carolinas and Virginia.
On Tuesday, Washington D.C.'s mayor, Muriel Bowser, declared a state of emergency in the District ahead of the hurricane, effective immediately.
All three states ordered mass evacuations along the coast.
In Virginia, 245,000 coastal residents were ordered to evacuate including from the Eastern Shore, another popular beachfront destination. "If we try to leave, we'll just get stuck in the rain", she said. The weakening of the winds doesn't mean this isn't going to be a bad storm, though.
Florence is expected to produce total rainfall accumulations of 15 to 20 inches and possibly 30 inches in some spots along its track over portions of North Carolina, Virginia and northern SC through Saturday. The Virginia National Guard is planning to initially bring up to 1,500 soldiers and airmen to offer help in the state's response operations.
At this height of the Atlantic hurricane season, Florence was being trailed on east-to-west paths by two other storms, Hurricane Helene and Tropical Storm Isaac, but neither packs the deadly punch of Florence.