Fierce winds and massive waves are expected to lash the coasts of North and SC and Virginia even before Florence makes landfall by early Friday, bringing a storm surge as much as 13 feet (4 meters), the National Hurricane Center in Miami warned.
The storm will likely hit the East Coast as a powerful Category 4 or possibly Category 5 hurricane, and its impact is expected to be life-threatening.
The large and powerful hurricane has prompted evacuation orders in North and SC and Virginia, as officials urge residents in coastal and low-lying areas to prepare for strong winds, a deep storm surge and a deluge of rainfall.
President Donald Trump declared states of emergency for North and SC and Virginia, opening the way for federal aid.
He has also cancelled campaign events Thursday and Friday in anticipation of the storm.
The storm rapidly intensified to Category 4 status Monday with sustained winds of 140 miles per hour.
Rain will overspread Virginia on Friday with tropical storm force winds possible on Saturday, especially across Southside Virginia. After that point, it would be hard for people in the storm's path to either finish preparations or flee affected areas.
"Florence is moving toward the west near 13 miles per hour".
It is then forecast to close in on North or SC on Thursday, hitting a stretch of coastline that is vulnerable to rising sea levels due to climate change.More news: 36% Less Likely to Buy Nike Products After Kaepernick Ad
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More news: Hurricane Florence: Your guide to the story
In girding for Florence, FEMA is making preparations in areas from SC to DE, with inland areas and mid-Atlantic states also expected to be inundated with what Long described as "copious amounts of rainfall". "We are totally prepared, we're ready, we're as ready as anybody's ever been", Trump told reporters in the Oval Office on Tuesday.
"There's 25% more people living between Charleston (South Carolina) and Morehead City (North Carolina) than there were when Hugo was making landfall", Myers said.
"That's good news and bad news", he said.
With so much focus on Florence, Porter is urging people to be wary of another storm developing in the Gulf of Mexico that could bring heavy rain and flooding to east Texas. "We're just a strip of land - we're a barrier island", she said.
"Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls".
In addition to flooding the coast with wind-driven storm surges of seawater as high as four metres, Florence could dump 38-64cm of rain, with up to 90cm in some spots, forecasters said. "So will the power lines, as the trees fall down". He said electric power could be out for weeks.
A ideal storm of unfortunate circumstances means Florence will likely be catastrophic for parts of the Southeast. It is now blowing with 130 miles per hour winds. At that level, it would still cause "devastating damage", according to the Saffir-Simpson scale.
MILLIONS of Americans are preparing for what could become one of the most catastrophic hurricanes to hit the eastern seaboard in decades, with Florence on the brink of a Category 5 and barrelling towards the US East Coast.
South Carolina Governor Henry McMaster ordered as many as one million coastal residents to leave their homes ahead of the storm's projected arrival on Thursday.