The storm's potential path also includes half a dozen nuclear power plants, pits holding coal-ash and other industrial waste, and numerous eastern pig farms that store animal waste in massive open-air lagoons.
Where is the hurricane now?
Horry and Georgetown counties shifted their operating conditions at noon Monday as Hurricane Florence continued to strengthen and head toward the Carolina coast.
Hurricane-force winds extend outward up to 30 miles from the center and tropical-storm-force winds extend outward up to 140 miles.
Florence bloomed into a category 4 monster on Monday as it made its way west across the Atlantic Ocean toward a possible landfall somewhere along the North Carolina coast late Thursday or early Friday.
As it nears the U.S. Atlantic shore, Florence will also benefit from "very warm" sea surface temperatures of up to 85 degrees, the NHC said.
Cooper and state emergency management officials held a media briefing about the state's preparation for Hurricane Florence, which strengthened to a category 4 storm.
Forecasters said Florence could become an extremely unsafe major hurricane sometime Monday and remain that way for days.
What else should I know?
South Carolina's state emergency management agency said on Sunday that it is "preparing for the possibility of a large-scale disaster".
Trump says government is 'absolutely, totally prepared' for Hurricane Florence
Also, looking like a direct hit on North Carolina, South Carolina and Virginia. "We are taking Hurricane Florence seriously". Florence's forecast cone for the next 48 hours has narrowed, indicating high confidence in the forecast track.
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In South Carolina alone, more than 1 million residents and tourists are expected to flee from coastal areas, Gov. Henry McMaster said Monday, vowing that state officials "are not going to gamble" with people's lives.
As of 5 a.m., Florence was centred about 625 miles southeast of Bermuda, moving west at 9 miles per hour.
As of 12pm EST, the storm was centered approximately 1,230 miles from Cape Fear, North Carolina.
It may bring catastrophic levels of rain and flooding to coastal and inland regions.
Maps of the storm's trajectory showed it likely to come ashore somewhere near the border of North Carolina and SC.
Since reliable record-keeping began more than 150 years ago, North Carolina has only been hit by one Category 4 hurricane: Hazel, with 130 miles per hour winds in 1954.
Current forecast models indicate that Florence could strike the Carolinas and enter central Virginia, possibly stalling and dropping more than 20 inches of rain in some areas. "I'd say get ready".
Florence went through significant strengthening and intensification Monday morning, starting the day as a Category 2 hurricane and strengthening to Category 4 by afternoon.
Some meteorologists are already predicting that Florence "could be one of the worst storms in USA history". Like Haley, McMaster also closed schools and government offices across the Midlands region of SC in order to allow roadways to accommodate the exodus from the coast. Of the two other storms, which remain far from land, Isaac poses the most immediate risk.
"Florence is a threat well beyond our coast", Cooper said.