In their latest update at 2am AST (7am BST), the NHC placed the hurricane about 624 miles south-east of Cape Fear, North Carolina.
The swirling mass of severe winds and rain has been categorised as a category four hurricane on the Saffir-Simpson Hurricane Wind Scale.
With maximum sustained winds reaching 140mph with higher gusts, Hurricane Florence is predicted to cause devastation when the storm reaches land.
On the Saffir-Simpson Hurricane Wind Scale, a category four storm is described as causing heavy irreparable damage, long-lasting water and electrical outages and heavily flooded terrain.
Despite the prediction of some weakening on Thursday, the NHC predicts Florence will remain a “dangerous major hurricane” when the centre reaches the coast.
More than 1.5million residents have been ordered to evacuate their homes along the southeast coast of the US, with North Carolina Governor Ray Cooper warning of the storm’s ferocity.
He said: “This storm is a monster. It’s big and it’s vicious.
“It is an extremely dangerous, life-threatening, historic hurricane.
“I can’t emphasise enough the potential for unbelievable damage from wind, storm surge and inland flooding.”
Florence’s movements are predicted to stall as the hurricane hits land, meaning a cascade of rain and heavy winds will smash into the Carolinas.
Damaging winds and catastrophic flash flooding is likely according to the NHC, over the Carolinas and the Mid-Atlantic States.
The NHC warned Florence is expected to produce total rainfall of “15 to 25 inches with isolated maximum amounts of 35 inches near the storm’s track over portions of the Carolinas and The Mid-Atlantic States from late this week into early next week.”
Storm surge warnings are in effect for South Santee River South Carolina to Duck North Carolina and Albemarle and Pamlico Sounds, including the Neuse and Pamlico Rivers.
A Storm Surge Watch is in effect for Edisto Beach South Carolina to South Santee River South Carolina and North of Duck North Carolina to the North Carolina/Virginia border.
A Storm Surge Warning means that there is “danger of life-threatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations.”
Whilst a Storm Surge Watch is defined as “a possibility of life-threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours.”
The National Weather Service in Wilmington, North Carolina, are warning that parts of the state could face “the storm of a lifetime”.
A statement from the weather experts said: “Just Thursday night alone 8-10 inches of rain will probably fall in the Cape Fear area, with additional heavy rain continuing into Friday.
“This will likely be the storm of a lifetime for portions of the Carolina coast.
“That’s saying a lot given the impacts we’ve seen from Hurricanes Diana, Hugo, Fran, Bonnie, Floyd and Matthew.”