The storm is now expected to make landfall in the lower Outer Banks of North Carolina early Friday morning or possibly stay in the ocean before making a shift to the left toward SC.
The Category 4 storm has maximum sustained winds of around 130 miles per hour.
Deal's declaration Wednesday covers comes as the National Weather Service's storm forecast shows a chance that Florence's track might turn toward the southwest as it approaches the Carolinas later this week.
Long lines formed at service stations, and some started running out of gas as far west as Raleigh, with bright yellow bags, signs or rags placed over the pumps to show they were out of order.
"This is not a storm that people need to ride out", Cooper told reporters. Florence is expected to also be a rainmaker, with totals of 35 inches possible in some areas.
Its expected sluggishness is becoming more common, possibly a result of climate change, said National Oceanic and Atmospheric Administration climate scientist and hurricane expert Jim Kossin.
Duke Energy, the nation's No. 2 power company, said Florence could knock out electricity to three-quarters of its 4 million customers in the Carolinas, and outages could last for weeks. "It's one of those situations where you're going to get heavy rain, catastrophic, life-threatening storm surge, and also the winds".
Forecasters in Wilmington, North Carolina, are emphasizing the potential for what they're calling "unbelievable damage from wind, storm surge, and inland flooding".
"Our sand dunes are healthy but they're not going to be able to keep back a wall of water like that", he said.
If the hurricane continues in a southwesterly direction, the Georgia coastline and inland counties will experience the outer bands of the storm, meteorologists said.
Melody Rawson evacuated her first-floor apartment in Myrtle Beach and arrived at Atlanta Motor Speedway in Hampton, Georgia, to camp for free with three other adults, her disabled son, two dogs and a pet bird.
He cited forecasts showing Florence was likely to stall over North Carolina, "bringing days and days of rain".
The latest data suggests at least 20 to 30 inches will fall on southeastern North Carolina including the Wilmington, Jacksonville, and Crystal Coast from Thursday through the weekend.
"Warming oceans, a more rapidly warming arctic, melting ice sheets are all contributing in various way to conditions like what we're observing now", Francis said.
South Carolina Governor Henry McMaster on Monday ordered the mandatory evacuation of one million coastal residents. "If you have to make large scale evacuations, make the call early".