Trump tweeted about the danger to Georgia Wednesday, saying, "Hurricane Florence may now be dipping a bit south and hitting a portion of the Great State of Georgia".
And there's "a huge difference" in the size and type of damage Florence inflicts if it stays 50 miles (80 kilometers) off shore versus heading inland immediately, Landsea said.
We've pulled together some of the key elements that explain why officials are so anxious, and what damage Florence could cause.
The slow movement, combined with the massive amount of moisture this storm holds, will bring risky rains - from 20 to 30 inches in coastal North Carolina, with 40 inches possible in isolated areas, the weather service says.
An estimated 10 million people live in areas expected to be placed under a hurricane or storm advisory, according to the US Weather Prediction Center.
Up to 1.7 million people have been ordered to evacuate across South Carolina, North Carolina and Virginia.
There have been warnings that any flooding of hog manure pits, coal ash dumps and other industrial sites could have a lasting effect on communities, with tainted water possibly washing into homes and drinking supplies.
So how are these people preparing?
Florence became a risky Category 3 hurricane Wednesday afternoon before it downgraded to a Category 2 Wednesday night with winds at 110mph. The more it stalls, the more it rains.
According to analytics firm CoreLogic, the hurricane could wreak more than $170billion (£130billion) in havoc and damage almost 759,000 homes and businesses.
Duke Energy, a power company in the Carolinas, estimated that one million to three million customers could lose electricity because of the storm and that it could take weeks to restore.
If the storm lingers for a few days, the sheer amount of rainfall could lead to catastrophic flooding. "We're still going to have a Category 4 storm surge". Smaller enclaves of Gullah, referred to as Geechee in some areas, are scattered along the Southeast coast from North Carolina to Florida.
Officials in the potential path of Florence urged people to evacuate their coastal homes and directed drivers away from the coast.
"A lot of our storefronts are boarded up", said Lynn Davis, town manager for Belhaven which sits at sea level in northeastern North Carolina. In 1999, Hurricane Floyd barrelled into the region and flooded vast areas with toxic water. "It is imperative that everyone follow local evacuation orders". "We're trying to get those last stragglers off of the barrier islands". "What can you do?" "You can't stop Mother Nature".
"I've been through hurricanes before but never with kids", she said. "It's going to happen". We want to make sure everybody knows that we are out.