After Florence makes landfall, that ridge, now over Washington and NY, will move east - but be replaced by another one forming over the Great Lakes that will likely keep the storm stuck, McNoldy said. According to the US National Hurricane Center, Florence is expected to strengthen further as it is ready to move over the southwestern Atlantic between Bermuda and the Bahamas on Tuesday and Wednesday.
Florence is so wide that a life-threatening storm surge was being pushed 480km ahead of its eye, and so wet that a swath of states from SC to OH and Pennsylvania could get deluged.
Byard, the FEMA official, said "this storm is not going to be a glancing blow". It may move a little north into Virginia or a little south into SC.
Hurricane Katrina intensified to a Category 5 with winds up to 175 miles per hour in the Gulf of Mexico, before striking Louisiana as a Category 3 storm.
US President Donald Trump said the "storm looks very bad" and urged people to take precautions.
"Some strengthening is expected during the next day or so, and Florence is expected to be an extremely risky major hurricane through Thursday night".
Florence interrupted her stay on North Carolina's Outer Banks.
The Federal Emergency Management Agency (FEMA) is warning residents on the eastern seaboard ahead of Hurricane Florence, calling it a "dangerous" and life-threatening storm.
According to the National Hurricane Center, Florence is expected to produce 15 to 20 inches of rain from a "prolonged and exceptionally heavy rain event" that may extend for "hundreds of miles" inland, with isolated totals to 30 inches over parts of North Carolina, Virginia and northern SC through Saturday.
The U.S. National Hurricane Center (NHC) has started sending out coastal advisories for Hurricane Florence at 8 a.m. on September 11.
Mr Graham said: "The water could overtake some of these barrier islands and keep on going".
Since then, the coastal population has grown by thousands of people.
"With time, the wind pushes the water into every nook and cranny you can think of".
"As there is a mandatory evacuation order in place for our region, our plant is now closed until further notice, a Volvos spokesperson told us".
Florence's projected path includes half a dozen nuclear power plants, pits holding coal-ash and other industrial waste, and numerous hog farms that store animal waste in huge lagoons.
"I would say everybody should get out, he said". Ryan Moser, a spokesman for the North Carolina-based electricity company Duke Energy, said operators would begin shutting down nuclear plants at least two hours before hurricane-force winds arrive. As previously reported by Heavy, the GFS model is still keeping the eye of the storm right on the coast.