It's now considered a Category 4 hurricane, but the NWS expects the storm to strengthen over the next day or so. The storm now has sustained winds of roughly 130 miles per hour.
The US Coast Guard closed ports in Wilmington and Morehead City, North Carolina and Hampton Roads, Virginia to inbound vessels greater than 500 tonnes and was requiring vessels of that size to leave if they did not have permission to be in the ports.
More than a million people are expected to flee low-lying areas, as SC and Virginia ordered mandatory evacuations of coastal areas starting on Tuesday.
The storm's first effects were already apparent on barrier islands as unsafe rip currents hit beaches and seawater flowed over a state highway - the harbinger of a storm surge that could wipe out dunes and submerge entire communities.
Storm surges up to 13ft are expected, according to the National Hurricane Center in Miami. "Additional watches and warnings may be required tonight or Wednesday", officials cautioned.
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U.S. President Donald Trump is expressing confidence the federal government is prepared for this week's onslaught of Hurricane Florence, which is predicted to be one of the most powerful storms in almost three decades to slam into the mid-Atlantic region.
Federal forecasters expect the storm to make landfall on Friday with 130 mile-per-hour (215 kph) winds and massive waves, with rains taking a heavy toll inland.
Hurricane Florence is expected to blast America's eastern seaboard tomorrow with winds over 140mph and "monumental" rainfall in possibly one of the most catastrophic storms in decades. "Don't bet your life on riding out a monster".
U.S. President Donald Trump speaks during an Oval Office meeting on hurricane preparations for Hurricane Florence at the White House in Washington, U.S., September 11, 2018.
"The safety of American people is my absolute highest priority", Trump said in the Oval Office at the conclusion of a briefing by the heads of the Department of Homeland Security and the Federal Emergency Management Agency. He also declared a state of emergency in Virginia.
"Specifically, FEMA is authorized to identify, mobilize, and provide at its discretion, equipment and resources necessary to alleviate the impacts of the emergency".
President Donald Trump has declared states of emergency for North and SC and Virginia, saying the U.S. government is "absolutely, totally prepared" for Florence.