Forecasters said wind speeds have dropped from a high of 140 miles per hour to 110 miles per hour, reducing it from a Category 4 storm to a Category 2, and additional fluctuations and weakening were likely as it swirled toward land.
Besides inundating the coast with wind-driven storm surges of seawater as high as 13 feet (4 meters) along the Carolina coast, Florence could dump 20 to 30 inches (51-76 cm) of rain, with up to 40 inches in parts of North Carolina, the NHC said.
The storm was downgraded to category three with maximum sustained winds of 120mph (195km/h), but officials say it is still "extremely dangerous".
Weather Underground meteorology director Jeff Masters said Florence eventually could strike as merely a Category 1 hurricane with winds less than 100 miles per hour, but that's still enough to cause at least $1 billion in damage.
He added that half of fatalities during hurricanes are caused by storm surges, and another quarter of deaths are due to inland rains and flooding. Tidal creeks throughout Brunswick, New Hanover, and Pender counties will also be at risk.
With Hurricane Florence, numerous coastline will see water levels from the storm surge rise over 3 feet, with some families seeing over 9 feet of water near their homes. For comparison, Hurricane Irene caused a 7-foot surge in 2011, and Hurricane Hazel caused an 18-foot surge in Calabash and Carolina Shores in 1954.
Three feet of storm surge moving onto the coastline will result in higher tides and higher water moving onshore. And Florence remained capable of unleashing rain-fueled catastrophic flooding of rivers and low-lying areas across a wide region. The first tropical-storm-strength winds are now expected to hit on Thursday at 2 p.m. and last throughout the weekend.
Wilmington, North Carolina, just north of where the hurricane is expected to come ashore, was sunny around midday yesterday as the town appeared to be emptying.
The latest flash flood predictions for Friday and Saturday.
The video was recently captured by scientists with the National Oceanic and Atmospheric Administration (NOAA) aboard a specialized four-engine aircraft.
An area from Virginia Beach to Charleston can also expect closer to 6 inches.
The enormous waves were recorded in the northeast quadrant of the hurricane, which is the strongest area of the storm.
The most recent predictions no longer have Florence traveling north, along the Atlantic coast.
Instead, the storm is now expected to make landfall over Wilmington, traveling south over Myrtle Beach between Friday and Saturday, and then traveling through SC and North Carolina to the Tennessee border through Sunday into Monday.