A state of emergency has been declared in Maryland, North Carolina, South Carolina, Virginia and Washington amid concern over potential torrential rain and flooding.
Trump declared states of emergency for North and SC and Virginia, opening the way for federal aid.
Landfall is expected late Thursday or early Friday, and the National Hurricane Center fears the storm "will slow considerably or stall, leading to a prolonged and exceptionally heavy and unsafe rainfall event Friday-Sunday". Then it is likely to hover along the coast Saturday, pushing up to 13 feet (nearly 4 meters) of storm surge and unloading water on both states.
Florence will bring large rainfall totals through Saturday in North Carolina, north SC and Virginia, causing catastrophic flash flooding. A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area.
Forecasters said Florence's eye could come ashore early Friday around the North Carolina-South Carolina line. "In light of the storm's forecasted southward track after making landfall, I encourage Georgians to be prepared for the inland effects of the storm as well as the ensuing storm surge in coastal areas".
The governors of Virginia, Maryland, North Carolina and SC have also declared a state of emergency for their states in preparation for Florence's arrival.More news: How Hurricanes like Florence Impact Consumer Spending
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Forecasts generally project Florence to make landfall in southeastern North Carolina on Friday as a Category 3 or 4 hurricane.
"The National Hurricane Center forecasts additional strengthening for Florence before it reaches the coastline of North Carolina and SC early Friday, Sept. 14", NASA wrote in the description of the video.
The impact of storm surge on the coast will depend on whether the storm's arrival coincides with high tide. Those areas are expected to experience tropical storm conditions and rainfall amount of up to 8 inches, and Puerto Rico and the Virgin Islands facing possible isolated amounts on 4 inches.
"Watch out, America! #HurricaneFlorence is so enormous, we could only capture her with a super wide-angle lens", German astronaut Alexander Gerst tweeted this morning, along with the photos to prove it. "Get prepared on the East Coast, this is a no-kidding nightmare coming for you".
That system could develop into a tropical depression by Thursday night.