Winds have dropped to about 40 miles per hour (65 kph) since it roared ashore along the USA mid-Atlantic coast on Friday as a hurricane and it is crawling west over two states at 6 mph (9 kph), the National Hurricane Center in Miami said early Sunday.
Water levels along the North and SC coasts are gradually receding as of Saturday night, the National Hurricane Center said.
Florence "will produce catastrophic flooding over parts of North and SC for some time", NOAA official Steve Goldstein said.
Officials in New Bern, which dates to the early 18th century, said more than 100 people were rescued from floods and the downtown was under water by Friday afternoon.
"We face walls of water at our coasts, along our rivers, across our farmland, in our cities and in our towns".
The storm dumped "epic" amounts of rain on North and SC as it trudged inland on Saturday.
Hurricane Florence made landfall Friday in Wrightsville Beach, North Carolina, after stalking the coastline for days.
And weather officials said more is coming, labeling as "extreme" the impacts from storm surge and flash flooding.
At 11 a.m. Saturday, Florence was centered about 40 miles (65 kilometers) west of Myrtle Beach, South Carolina, moving west at 2 mph (4 kph), not even as fast as a person can walk. It has 3½ times more storms that reach major hurricane strength of 111 miles per hour (178 kph), and three times more accumulated energy out of those hurricanes, an index that measures not just strength and number of storms but how long they last, according to more than 65 years of storm data.
"Amazing. They did awesome", said Knox, who was stranded with seven others, including a boy carried out in a life vest.
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Additionally, "inspectors have checked 150 drainage hotspots, and 200 slopes known to have caused problems in the past". However, it's not too late to prepare for Hurricane Florence - or any other storm that may move through Coweta County.
Tornadoes remain a threat, with the NHC saying that "a few tornadoes are possible in southeastern North Carolina and northeastern SC". Electricity remained out for much of the city, known for its historic mansions, with power lines lying across roads like wet strands of spaghetti.
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. But with half of the storm still out over the Atlantic, Florence continued to collect warm ocean water and dump it onshore.
Across the Trent River from New Bern, Jerry and Jan Andrews returned home after evacuating to find carp flopping in their backyard near the porch stairs.
"The shelves are pretty empty, and we don't expect our first truck until Sunday, maybe, if they can get through", she said.
"The slow motion of the storm will make this a very prolonged flood event", Reid Hawkins, science officer for the National Weather Service office in Wilmington, said in a briefing. "We're trying to educate and protect Floridians so they don't fall victim to Irma for a second time".
High winds and storm surge from Hurricane Florence hits Swansboro N.C., on September 14, 2018.
Munich Re's Rauch said about 30 to 50 percent of storm damage is usually insured in the United States but often less than 10 percent in developing countries, meaning nine-tenths of the people hit will end up shouldering a bigger economic burden.
SC authorities said law enforcement officers were guarding against looting in evacuated areas, while Wilmington set a curfew on Saturday evening in response to looting in one area.
"WE ARE COMING TO GET YOU", the city tweeted during the height of the storm.