It was expected to make landfall near Cape Fear, North Carolina, whose river was forecast by Monday to reach two feet above the record level it hit during Hurricane Floyd in 1999, the National Weather Service said.
More than 30,000 United States retail bank branches - 34% of the country's branch network - are now at risk of facing tropical storm force winds from Hurricane Florence over the coming days, according information compiled by data analytics firm Qlik.
"We're a little anxious about the storm surge so we came down to see what the river is doing now", said Linda Smith, 67, a retired nonprofit director.
In less than 24 hours, Florence has dropped from category 4 to category 2.
So what exactly is a storm surge and how is it created?
Aside from wind-shear dangers, concerns are now shifting to flooding and storm surge issues. Projections as of 5:00am EST on September 13, 2018. This implies that water, even more so than wind, is the most risky element of a major storm. Like a giant hair dryer, these winds push seawater into low-lying marshland and delta areas. Its surge could cover all but a sliver of the Carolina coast under as much as 11 feet (3.4 meters) of ocean water, and days of downpours could unload more than 3 feet (0.9 meters) of rain, touching off severe flooding.
Roads and intersections on North Carolina's Outer Banks barrier islands were already inundated with water.
Gerst tweeted some more images and warnings to the people in the path of the storm. That makes it hard to project how the region will ultimately be affected.
SC governor issues evacuation for Grand Strand area
Stay with WTOC for the latest information on Lowcountry closings and weather as Hurricane Florence continues to draw closer. It is feared Florence could hit the Carolinas harder than any hurricane since Hurricane Hazel packed 209km/h winds in 1954.
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".
And there is also a major threat from freshwater, with warnings of "catastrophic" flooding from lakes, rivers and freshwater reserves expected over parts of the Carolinas and Virginia. His group, the Office of Water Prediction and Luettich's team are working together to build such models now. More flights were expected to be grounded and more airports were preparing to shut down operations as the storm moves inland.
After hitting the North Carolina coast, the hurricane will cut down into SC before sweeping into western North Carolina and north from there.
With South Carolina's beach towns more in the bull's-eye because of the shifting forecast, OH vacationers Chris and Nicole Roland put off their departure from North Myrtle Beach to get the maximum amount of time on the sand.
Will Epperson, a 36-year-old golf course assistant superintendent, said he and his wife had planned to ride out the storm at their home in Hampstead, North Carolina, but then reconsidered. Her team manages 32 wild horses living in the Rachel Carson Reserve near Beaufort, North Carolina.
"I have big, huge pine trees in my yard and a one story house with a lot of windows, so I'm really anxious what I'm gonna find when I get home", Morgan said.
Still, a storm surge can overwhelm the animals, as it did in 2003 when Hurricane Isabel killed five horses and swept three others a few miles away.