"This storm is big and it's vicious", North Carolina Governor Roy Cooper said on NBC's "Today" Show on Wednesday. "You're going to be displaced from your home in coastal areas".
Predictions now have the storm stalling and making a slight southward turn after it makes landfall.
The latest meteorological predictions show that Hurricane Florence will have the strongest impact in the Carolinas, particularly in SC. After Florence's rain starts to fall this week, he said, the rainfall could continue through Monday.
It was located 925 kms east-southeast of Cape Fear, North Carolina, and moving at 28 kph in a west-northwest direction.
Georgia Governor Nathan Deal declared a state of emergency in the southern USA state on Wednesday ahead of the arrival of Hurricane Florence. Georgia Gov. Nathan Deal followed suit on Wednesday.
The NHC said Florence's official track forecast could be adjusted further south soon, reflecting increasing pressure from this ridge pushing the storm more toward SC and Georgia.
The culprit, according to the National Hurricane Center, is a developing pressure ridge that will slow Florence down near landfall and after landfall and push the storm as it downgrades into a tropical storm and then a tropical depression inland down through SC and into Georgia Saturday, Sunday and early Monday. Strong winds can in themselves be very damaging, leading to roof damage, tree damage, and even mass structural damage.
"This will likely be the storm of a lifetime for portions of the Carolina coast", the National Weather Service in Wilmington, North Carolina, said in its forecast.
Those included Topsail and North Topsail beaches in Pender and Onslow counties; Carolina, Kure and Wrightsville beaches in New Hanover County; and "low lying areas and sub-standard housing" in Brunswick County.
In addition to those dangers, the hurricane center said in its 2 p.m. ET update, "A few tornadoes are possible in eastern North Carolina beginning late Thursday morning".
As of Tuesday, more than 1.7 million people in the Carolinas and Virginia were warned to clear out.
Storm surge flooding does not include floods caused by the heavy rain from the hurricane, such as what happened previous year in Houston with Hurricane Harvey and in North Carolina in 2016 during Hurricane Matthew.
In Charleston, S.C., the local government said that after giving out 53,000 sandbags, "there is no longer any sand available at any city of Charleston location".
Walking his dog along empty streets, Belli said he's well stocked with food and water. It may drift around the South Carolina/North Carolina border for about 24 to 36 hours. Florence is now heading for ocean water with surface temperatures of around 85 degrees, meaning it will likely strengthen on its way to the East Coast.
Forecasters: Depression becomes Tropical Storm Michael
Michael is the 13th named storm of the 2018 hurricane season, according to hurricane center spokesman Dennis Feltgen. Another important factor is where and when the storm begins to turn from heading due north to northeast.
If these projections hold, University of Miami hurricane researcher Brian McNoldy says "it's exceptionally bad news, as it smears a landfall out over hundreds of miles of coastline, most notably the storm surge".
Satellite images show the storm has maintained a distinct eye, and it's well organized. Its maximum sustained winds are expected to top 145 miles per hour before losing some steam near the coast.
"Plan for extreme wind of equivalent CAT 3 hurricane force or higher due to possible forecast changes in track, size, or intensity", the National Weather Service says.
"Been through it!" Belli said, referring to Hurricane Hugo, which caused widespread damage in SC in 1989. "So Florence is kind of spreading out, becoming a much larger, more stable hurricane".
The storm is expected to arrive on the East Coast as early as Thursday, and is expected to ride north for several days.
Forecasters in Wilmington, North Carolina, are emphasizing the potential for what they're calling "unbelievable damage from wind, storm surge, and inland flooding".
In the Charleston region, Walmart closed 10 of its outlets in the area at midnight on Monday after Gov. Henry McMaster issued an evacuation order for the coast of SC.
"This is a hurricane event followed by a flood event", said South Carolina Governor Henry McMaster.
The tropical storm-force winds extend 280 miles across the Atlantic Ocean, which is far enough to reach from Boston to Philadelphia.
Byard added that this "is not going to be a glancing blow. It's a big one", he said.
To back up that point, Graham cited a sobering statistic: "50 percent of the fatalities in these tropical systems is the storm surge - and that's not just along the coast".
Another 25 percent of deaths are related to rain, he said.
"We are already experiencing heavily impacted traffic on some of the evacuation routes", said Jeff Byard, the associate administrator for response and recovery at the Federal Emergency Management Agency (Fema).