Don't be fooled by the fact that Florence has weakened slightly to a Category 2 hurricane; categories only denote the speed of sustained winds. And the more it hovers just off shore - a distinct possibility - the more potentially deadly storm surge it pushes on-shore.
NHC Director Ken Graham warned that rivers up to 60km inland may flood. Potential threats from hurricanes include powerful winds, heavy rainfall, storm surges, coastal and inland flooding, rip currents, tornadoes, and landslides.
BMW of North America has a plant in Spartanburg, South Carolina, almost 300 miles (483 km) inland from the life-threatening hurricane's projected point of landfall on Friday, and automobile shipments were diverted.
Southwest Airlines has canceled all its flights in and out of RDU on Thursday and Friday and doesn't plan to resume operations until at least Saturday, according to the airport's website.
And it led to mixed signals from officials in SC, whose governor had canceled mandatory evacuation for several coastal counties.
Cooper and his SC counterpart, Henry McMaster, told the more than 1 million people who have been directed to leave that if they don't do so, they are on their own.
The storms path is promising to bring even more devastation than first predicted to the Carolinas and parts of Georgia.
In Virginia, where about 245,000 residents were ordered to evacuate low-lying areas, officials urged them to stay in safer locations despite forecast changes showing Florence's path largely missing the state.
Florence is so wide that a life-threatening storm surge was being pushed 485 km ahead of its eye, and so wet that a swath from SC to OH and Pennsylvania could get deluged.
Florence is expected to make landfall late Thursday night or early Friday morning, Mountain Time, somewhere between Atlantic Beach, NC and Savannah, GA.
"I'm not approaching Florence from fear or panic", said Brad Corpening, 35, who planned to ride out the storm in his boarded-up delicatessen in Wilmington.
"This is a very unsafe hurricane", Mr McMaster said, adding that the evacuation order for coastal counties was "mandatory, not voluntary".
"Get out of its way, don't play games with it, it's a big one, maybe as big as they've seen", Trump said.