Millions of Americans are preparing for what could be one of the most catastrophic hurricanes to hit the eastern seaboard in decades.
Hurricane Florence’s top winds dipped to 130mph on Tuesday morning, but it remains a Category 4 storm and is expected to approach Category 5 status as it slows and strengthens over warm ocean water off the coast of North and South Carolina.
The centre of the storm is forecast to meander Thursday, Friday and Saturday over a stretch of coastline saturated by rising seas, inundating several states with rainfall and triggering life-threatening floods.
“Please be prepared, be careful and be SAFE!” President Donald Trump tweeted on Monday evening.
Mandatory evacuations are under way for parts of three east coast states, and the mayor of Washington DC declared a state of emergency as the capital prepares for heavy rain and flooding.
South Carolina’s governor ordered the evacuation of the state’s entire coastline on Tuesday and predicted that a million people would flee as major roads reverse directions.
Virginia’s governor ordered a mandatory evacuation for some residents of low-lying coastal areas, while some coastal counties in North Carolina have done the same.
North Carolina governor Roy Cooper said his state is “in the bullseye” and urged people to “get ready now”.
The centre of that bullseye may be Camp Lejeune, a sprawling Marine Corps training base. Tuesday’s forecast showed 20in or more falling there, part of a wide stretch of rainfall that could total 10in or more over much of Virginia and drench the nation’s capital. Some isolated areas could get 30in, forecasters said.
Florence could hit the Carolinas harder than any hurricane since Hazel packed 130mph winds in 1954.
That Category 4 storm destroyed 15,000 buildings and killed 19 people in North Carolina. In the six decades since then, many thousands of people have moved to the coast.
The storm’s first effects were already apparent on barrier islands as dangerous rip currents hit beaches and seawater flowed over a state highway — the harbinger of a storm surge that could wipe out dunes and submerge entire communities.
Watches are already in effect for a storm surge that could reach up to 12ft at high tide on a stretch from Cape Fear to Cape Lookout in North Carolina, forecasters said.
A hurricane watch was in effect for Edisto Beach, South Carolina, to Virginia’s southern border, with the first hurricane-force winds arriving late on Thursday.
If Florence slows to a crawl just off the coast, it could bring torrential rain all the way into the Appalachian mountains and as far away as West Virginia, causing flash floods, mudslides and other dangerous conditions in places that do not usually get much tropical weather.
Craig Fugate, former director of the Federal Emergency Management Agency, said: “This is going to produce heavy rainfall, and it may not move very fast. The threat will be inland, so I’m afraid, based on my experience at Fema, that the public is probably not as prepared as everybody would like.”
National Hurricane Centre director Ken Graham warned that Florence is expected to linger once onshore, downing trees, knocking out electricity and causing widespread flooding.
Mr Graham warned that the “staggering” size of the storm means its impacts will be felt far and wide.
The storm’s potential path also includes half a dozen nuclear power plants, pits holding coal-ash and other industrial waste, and numerous pig farms that store animal waste in massive open-air lagoons.
Airlines including American, Southwest, Delta and JetBlue are letting affected passengers change travel plans without the usual fees.
A warm ocean is the fuel that powers hurricanes, and this area of the ocean is seeing temperatures peak near 30C, hurricane specialist Eric Blake wrote.
With little wind shear to pull the storm apart, Florence’s hurricane-strength winds are expanding, reaching 40 miles from the eye of the storm, with tropical storm-force winds reaching up to 150 miles.
On Tuesday morning, Florence was centred about 905 miles east-south-east of Cape Fear, North Carolina, and moving west-north-west at 16mph.
Its centre will move between Bermuda and the Bahamas on Tuesday and Wednesday and approach the coast of South Carolina or North Carolina on Thursday.
Two other storms are spinning in the Atlantic as the 2018 hurricane season reaches its peak. Isaac became a tropical storm again approaching the Caribbean, while Hurricane Helene was veering northwards, posing no threat to land.
In the Pacific, Olivia became a tropical storm again on a path to hit Hawaiian islands early on Wednesday.
South Carolina governor Henry McMaster said an estimated one million people would be fleeing his state’s coast, with eastbound lanes of major routes reversed to ease the exodus.
Virginia governor Ralph Northam’s evacuation order applies to about 245,000 people, including parts of the Hampton Roads area and Eastern Shore.