Hurricane Dorian is back up to a Category 3 storm, and has begun raking the Southeast US seaboard, threatening to inundate low-lying coasts from Georgia to southwest Virginia with a dangerous storm surge after its deadly mauling of the Bahamas.

Dorian had crashed into the island nation as its strongest hurricane on record leaving widespread devastation and at least 20 people dead.

However, 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 about 12 hours or so, but guidance is showing shear increasing, and that should result in gradual weakening Thursday and Friday, according to the National Hurricane Center.

Dorian still boasted dangerously high winds of 185 km/h as it churned north toward the Carolinas while pushing crashing ocean waves onshore.

More than 1,500 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.

Though weakened, 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.

Late on Wednesday the distinct eye of the hurricane churned about 168 kilometres south of Charleston, moving north at 11 km/h off the coast.

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.

Hundreds of thousands also were ordered off the Georgia 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, four meters, was set by Hugo in 1989.

Hurricane Dorian has gone back up to Category 3 strength with 115 mph winds as it continues to approach the South Carolina coast https://t.co/thCuMcLYmA pic.twitter.com/zWJlEP4Fcz

— CNN Breaking News (@cnnbrk) September 5, 2019

Georgia’s coastal islands were also at risk, Governor Brian Kemp said Wednesday, adding “We are very worried, especially about the barrier islands getting cut off.”

The approach of Dorian has left the cobblestone streets of Savannah, Georgia’s downtown historic district largely deserted. But there were still places to find a hurricane party. More than 30 people gathered at Pinkie Master’s Lounge on Wednesday evening, as wind gusts from the offshore hurricane bent tree tops in Savannah – nearly 32 kilometres inland.

In North Carolina, where authorities said an 85-year-old man died after falling from a ladder while getting ready for Dorian, Governor Roy Cooper warned of the threat of storm surge and flash flooding from heavy rains. The Outer Banks barrier islands were particularly exposed.

Duke Energy said Dorian could cause more than 700,000 power outages in easternmost parts of North Carolina and South Carolina, and Georgia Power said about 2,800 homes and businesses were already without electricity.

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 4,000 federal responders; 6,000 National Guard members; and 40,000 utility workers were on standby.

-AAP