"It truly is really about the whole size of this storm", National Hurricane Center Director Ken Graham said. The power company has warned that up to 3 million people could be left without power for an extended period of time following Hurricane Florence. More than 26,000 hunkered down in shelters.
The latest rainfall projections warn of 20-40 inches of rain from coastal North Carolina into northeastern SC - amounts that could bring "catastrophic flash flooding", the hurricane center said. As of Saturday, about 676,000 homes and businesses were without power in North Carolina, along with 119,000 in SC.
"This is going to be a Mike Tyson punch to the Carolina coast", said Jeff Byard, associate administrator for response and recovery at the Federal Emergency Management Agency.
SC authorities reported one death.
Trump, who plans a visit to the region next week, tweeted his "deepest sympathies and warmth" to the families and friends of those who had lost their lives.
As of 8 p.m., Florence was centered about 85 miles (135 kilometers) southeast of Wilmington, its forward movement slowed to 5 mph (7 kph).
President Trump spoke with the senators of North Carolina and SC, telling them they have the full support of the federal government and the feds will be there to help with anything their states may need.
The forecast calls for as much as 102cm of rain over seven days along the coast, with the deluge continuing even as the centre of the storm pushes its way over the Appalachian Mountains.
A hurricane warning is in effect for a big chunk of the Carolina coast, from the South Santee River below Myrtle Beach, S.C., to Duck, N.C. - part of the Outer Banks. Officials say people refusing to evacuate could end up alone, drenched and in the dark, as rescue crews won't go out to help in winds above 50 miles per hour (80 kph).
"The worst is yet to come", he added. When Hurricane Floyd made landfall near Cape Fear in 1999 as a Category 2 storm, bloated carcasses of hundreds of thousands of hogs, chickens and other drowned livestock bobbed in a nose-stinging soup of fecal matter, pesticides, fertilizer and gasoline so toxic that fish flopped helplessly to escape it. "So will the power lines, as the trees fall down". Florence's heavy rains could cause an environmental disaster if waste from hog manure pits, coal ash dumps and other industrial sites washes into homes or threatens drinking water supplies.
The hurricane, whose strength has been compared to a direct hit by Mike Tyson, advances with maximum sustained winds of 175 kilometres per hour. Isolated tornadoes could also occur along North Carolina's coast on Thursday, according to the National Weather Service in Wilmington.
In New Bern, about 90 miles northeast of Wilmington at the confluence of two rivers, Florence overwhelmed the town of 30,000 and left the downtown area under water. The Charleston area is under a storm surge watch. Local officials will let the public know when it's safe to return, she said.
Wind and the tidal surge will be the biggest issues for airports in the coastal Carolinas, FlightAware's Orsi said.