As the storm continues toward Southeastern North Carolina, it will bring life-threatening storm surges, flooding and risky waves to the coast, the briefing said.
Florence's winds had dropped from a peak of 140 miles per hour (225 kph) to 105 miles per hour (165 kph) by midmorning, reducing the hurricane from a terrifying Category 4 to a 2.
That's because the weather systems that usually push and pull a storm are disappearing as Florence nears land around the border between North and SC.
Roy Cooper warned residents to not let their guard down ahead of Hurricane Florence's landfall later this week.
The NHC said the first tropical storm-force winds of at least 39 miles per hour would hit the region early on Thursday with the storm's center reaching the coast Friday.
Trouble began brewing last week, when three hurricanes-Florence, Isaac, and Helene-starting churning up the North Atlantic.
The News & Observer reports that the storm's path shifted early Wednesday and it is now bearing down on southern North Carolina and northern SC, where it could dump up to 40 inches of rain in places.
Florence's weakening as it neared the coast created tension between some who left home and authorities who anxious that the storm could still be deadly. Technically this means Florence is no longer a "major" hurricane, and may not be when it reaches the North Carolina coast early on Friday morning. "Once these winds start blowing at that tropical storm rate, it will be virtually impossible for the rescuers to get in to rescue you".
Will Epperson, a 36-year-old golf course assistant superintendent, said he and his wife had planned to ride out the storm at their home in Hampstead, North Carolina, but reconsidered due to its ferocity.
The full impact of storm surge on the coast will depend on whether the storm's arrival coincides with high tide.
Florence's worst aspect: its slowing down and stalling over coastal areas, causing up to 19-foot storm surges, and dropping from 6 to 40 (!) inches of rain.
Roslyn Fleming, 56, said her granddaughter was baptized in the inlet near where she lives in the coastal community of Sea Breeze and on Thursday morning she used her iPad to make a video of the scene.
Where exactly the zone of heaviest rain sets up as the storm meanders inland is more uncertain, but models suggest that it may concentrate in southern North Carolina and northern SC through the weekend.
"If you're going to leave. you should leave now because time is running out", McMaster said on Thursday. Tornadoes are possible Thursday in eastern North Carolina.
"What to do when a hurricane is barreling towards you, school is cancelled for the week, + kids are faaaareaking out?" she wrote on the social media site.
Boeing evacuated several new 787-10 Dreamliner jets from its factory in North Charleston, South Carolina, to protect them from the storm.
As of 2 a.m. Thursday, was about 235 miles east southeast of Wilmington, N.C., and about 280 miles east southeast of Myrtle Beach, S.C., moving northwest at 17 mph.
A power outage model run at the University of MI projects that 3.2 million customers will be without electricity because of the storm, mostly in the eastern half of North Carolina.