Hurricane Dorian, back to a Category 3 storm, has begun raking the southeast US seaboard and left tens of thousands without power as it threatened to inundate low-lying coasts from Georgia to Virginia with a life-threatening storm surge after its deadly mauling of the Bahamas.
Dorian squatted over the island nation as its strongest hurricane on record, leaving widespread devastation and at least 20 people dead.
But it weakened substantially in the days since, dropping from a Category 5 to a Category 2 storm before increasing again late Wednesday.
Dorian could maintain this intensity for several days before gradually weakening through Saturday, according to the National Hurricane Center.
As of early Thursday more than 68,700 customers in Charleston County and over 15,200 in Beaufort County were without power, according to Dominion Energy. Berkeley Electric Cooperative reports another 12,600 lost electricity in Charleston County.
Duke Energy in a news release Wednesday said it expected the storm to cause 700,000 outages in the Carolinas and that it brought in resources from 23 states and Canada to respond "as soon as it was safe to do so".
More than 1500 people sought refuge in 28 shelters in South Carolina, where sheets of rain began falling late Wednesday in the historic port city of Charleston, located on a peninsula prone to flooding.
As Dorian crept dangerously closer, winds picked up sending rain sheets sideways, thunder boomed in the night sky and power flickered on and off in places.
Dorian remained a force to be reckoned with, its swirling circle of winds and rain wrapped around a large, gaping eye visible on photos taken from space.
At 8am EDT Thursday the distinct eye of the hurricane churned about 115 kilometres south-southeast of Charleston, moving north at 13km/h off the coast with dangerously high winds of 185km/h extending about 95 kilometres outward.
Hurricane warnings were in effect for the coasts of both South and North Carolina. Forecasters said Dorian's centre could move over the coast of North Carolina Thursday night or Friday before gaining forward speed and moving off the coast of New England on Saturday.
In Charleston's downtown, stores and restaurants were boarded up with wood and corrugated metal and about 830,000 people were under mandatory evacuation orders on the South Carolina coast.
A flood chart posted by the National Weather Service projected a combined high tide and storm surge around Charleston Harbor of 3.1 metres. The record of four metres was set by Hugo in 1989.
Hundreds of thousands also were ordered off the Georgia coast. Georgia Governor Brian Kemp said "we are very worried, especially about the barrier islands getting cut off".
In North Carolina, where authorities said an 85-year-old man died after falling from a ladder while preparing his home for Dorian, Governor Roy Cooper warned of a coming storm surge and flash flooding from heavy rains.
In Florida, initially projected to take a direct hit, there was widespread relief Wednesday after Dorian passed by from a relatively safe distance offshore
The Navy ordered ships at its huge base in Norfolk, Virginia, to head to sea for safety, and warplanes at Langley Air Force Base in Hampton, Virginia, were being moved inland.
The commander of the Navy Region Mid-Atlantic issued an emergency evacuation order for military personnel and their dependents in five North Carolina counties.
The acting administrator of the Federal Emergency Management Agency, Peter Gaynor, said 4000 federal responders, 6000 National Guard members and 40,000 utility workers were on standby.
"We are ready to go," Gaynor said. "We'll follow Dorian up the coast until it is not a threat."
Australian Associated Press