Another 4 million people are under a tropical storm watch.
Major US military installments may be in the path of the Florence, including the largest Marine base at Camp Lejeune in North Carolina and the world's biggest Navy base in Norfolk, Virginia. "This is not just a coastal event".
Taking dead aim at the Carolinas, Storm Florence is likely to bring "life-threatening, catastrophic flash flooding and significant river flooding" when it sweeps in on Thursday and Friday, the National Weather Service (NWS) said. Unfortunately, the forecast is for the storm to stall out and drop a ton of rain in the Carolinas.
"The water could overtake some of these barrier islands and keep on going".
Standard guidance for impending weather emergencies is to ensure that you have enough non-perishable food and water for several days, flashlights and batteries, medications, and other essentials.
Rain measured in feet is "looking likely", he said.
Officials warned there was a chance of "life-threatening inundation from rising water" as the hurricane is due to hit land on Friday.
Its strong winds and storm surge had devastating consequences.
The National Hurricane Center says storm surge from Hurricane Florence could be up to 13 feet in some areas of North Carolina.
US President Donald Trump has authorised emergency measures to free up federal funds to help those responding to the storm.
South Carolina Gov. Henry McMaster ordered the evacuation to start at noon Tuesday as Hurricane Florence approaches. As it turns into southern SC.
On Wednesday and Thursday, Florence is predicted to move across a band of water that's around 84 degrees Fahrenheit (29 degrees Celsius), which is 3 or 4 degrees Fahrenheit (1.6 to 2.2 degrees Celsius) higher than average for this time of year.
"FEMA resources are going to the Virginia-Carolina area to be in place before the storm hits", Goldstein said. Author of "The Edge of Disaster: Rebuilding a Resilient Nation".
First comes the storm surge - a rise in sea levels caused by storm winds.
Preparations for Florence were intensifying up and down the densely populated coast.
Goldstein says the team should arrive in SC by dinnertime.
"I've been doing this since 1983", Roberts said as he completed an order for another 18-wheeler full of supplies. "This is the craziest one".
The storm is on track to land a rare direct hit on the Carolinas, similar to Hurricane Hugo, which slammed into SC, near Charleston, in 1989. "The biggest thing is you're always anxious about yourself and friends and family - and whether they'll have a place to come back to", he said.
"I'm telling them to go inland, but I'm anxious about the rain and tornadoes too", Roberts said.