A mandatory evacuation will start at noon Tuesday for eight coastal counties, McMaster said in a press conference Monday afternoon.
The storm's first effects were already apparent on barrier islands as risky rip currents hit beaches and seawater flowed over the road. "Probably not too much better, but most likely safer than here", she said.
The storm's potential path also includes half a dozen nuclear power plants, pits holding coal-ash and other industrial waste, and numerous pig farms that store animal waste in massive open-air lagoons.
Hurricane Florence is packing maximum sustained winds of 140 miles per hour and higher gusts on Tuesday morning.
With little wind to pull the storm apart, Florence's hurricane wind field is expected to expand over coming days, increasing its storm surge and inland wind threats.
"To the incredible citizens of North Carolina, South Carolina and the entire East Coast - the storm looks very bad!"
Carrying winds of up to 220 km/h, Hurricane Florence - a Category 4 storm - is expected to strengthen and possibly become Category 5 on Tuesday.
Other top officials involved in last year's hurricane season, including Long and Nielsen, also remain in place.
Preparations for Florence are intensifying up and down the densely populated coast. Currently, Florence has winds of 140 miles per hour (220 kilometers/hour), making it a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale, the National Hurricane Center reported.More news: Rat causes Chinese restaurant chain to lose £145 million in value
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North Carolina's governor declared a state of emergency on Sunday, one day after SC.
A hurricane warning is in effect from the South Santee River in SC to Duck, North Carolina. Schools, state government offices and medical facilities, including nursing homes in those counties, will be evacuated as well, McMaster said.
"People are getting frantic, I know some people were upset when we were out of gas", Schrock said in a phone interview.
The Atlantic hurricane season officially began June 1, but cooler water and higher wind shear - winds moving at different speeds and directions - early in the season are less than ideal for tropical systems to gain and maintain strength.
Manning adds hundreds of troops are ready to deploy at a moments notice, while the Federal Emergency Management Agency is setting up operations at Fort AP Hill, in Virginia.
The Robert T. Stafford Disaster Relief and Emergency Assistance Act, 42 U.S.C. §§ 5121-5207 (the Stafford Act) §401 states in part that: "All requests for a declaration by the President that a major disaster exists shall be made by the Governor of the affected State".
Several meteorologists said Florence could approach what Hurricane Harvey did previous year over Texas, dumping days of rain over a wide area.
The University of North Carolina at Wilmington, near the shore, canceled its upcoming alumni weekend and all classes starting at noon Monday, encouraging its students to leave campus for a safer location.
The event, called "Shooting Guns at Hurricane Florence To Scare It Away", is scheduled from September 11 to 15 in Richmond, Virginia, and is hosted by Ryan Stumpf.