Doll said that people living in low-lying areas next to streams, creeks and rivers, especially in farther inland areas, need to pay attention and evacuate in case rivers start flooding.
The center of the eye of the hurricane made landfall in Wrightsville Beach, North Carolina, and was moving slowly westward just south of Wilmington.
Trump, who plans to visit the region next week and he tweeted his "deepest sympathies and warmth" to the families and friends of those who had lost their lives.
Florence flattened trees, buckled buildings and crumpled roads.
North Carolina's governor Roy Cooper said: "Know that water is rising fast everywhere, even in places that don't typically flood".
The Neuse is expected to crest at more than nine feet (3 meters) above flood stage Monday and Sheehan said the company expects the same ash basins are likely to be inundated again.
At least 14 deaths from the storm have been confirmed, including a man and a woman in Houry County who died from carbon monoxide poisoning. "This system is unloading epic amounts of rainfall". Swansboro, a town near North Carolina's coast, received 30.58 inches of rainfall as of Saturday morning, setting a record for tropical storm-associated rainfall in the state, meteorologist David Roth said.
Emergency workers went door to door urging people to flee Florence's rising waters and used inflatable boats to rescue others as the storm practically parked itself over land and poured on the rain Saturday, raising fears that North Carolina could be in for the most disastrous flooding in its history.
Charles Rucker, a retired teacher, had only spent five nights in his newly-purchased house, built in 1830, when Florence struck. Nothing I ever experienced before, I was truly scared, ' he told AFP. More than 22,600 people were housed in 150 shelters statewide.
"I have never seen flash flooding like this in our state", said state North Carolina Transport Secretary Jim Trogdon. In Pender County, a woman died of a heart attack after paramedics trying to reach her were blocked by debris.
In Washington, President Donald Trump was briefed by telephone Saturday on Florence's impact.
A resident stops his vehicle to look at the statue of a bear, the city's symbol, that was dropped in the middle of the street by storm surge produced by Hurricane Florence Sept. 15, 2018, in New Bern, North Carolina.
Cooper said others should not follow suit. Disaster response efforts are underway.
Besides federal and state emergency crews, rescuers were being helped by volunteers from the "Cajun Navy" - civilians equipped with light boats, canoes and air mattresses - who also turned up in Houston during Hurricane Harvey to carry out water rescues.
Florence already has proven deadly with its almost nonstop rain, surging seawater and howling winds, and the threats are days from ending as remnants from what was a major hurricane swirl over the Carolinas.
Hurricanes usually drive people away from Florida, but Florence is making the Sunshine State into a refuge for people from the Carolinas.