The U.S. National Hurricane Centre said early Friday that Florence was about to make landfall in North Carolina, bringing with it life-threatening storm surge and hurricane strength winds.

The powerful storm already has inundated coastal streets with ocean water and left tens of thousands without power, and forecasters say that “catastrophic” freshwater flooding is expected over portions of the Carolinas as Hurricane Florence inches closer to the U.S. East Coast.

Florence’s eyewall is beginning to approach the North Carolina coast and is expected to cause life-threatening storm surge, the centre said at around 4:30 a.m. ET on Friday.

A man walks past a boarded-up business in Wilmington, N.C., ahead of the storm. The storm’s slowing forward movement and heavy rains had Gov. Roy Cooper warning of an impending disaster. (Carlo Allegri/Reuters)

It said that a gauge in Emerald Isle, N.C., recently reported 1.92 metres of inundation. Emerald Isle is about 135 kilometres north of Wilmington.

And about 74 kilometres north of Emerald Isle in New Bern about 150 people were waiting to be rescued from rising flood waters, WXII-TV reported. The city said early Friday that two out-of-state FEMA teams were working on swift-water rescues and more teams were on the way.

Screaming winds bent trees toward the ground and raindrops flew sideways as Florence’s leading edge whipped the Carolina coast to begin an onslaught that could last for days, leaving a wide area under water from both heavy downpours and rising seas.

The storm’s intensity diminished as it neared land. But that, combined with the storm’s slowing forward movement and heavy rains, had North Carolina Gov. Roy Cooper warning of an impending disaster.

“The worst of the storm is not yet here but these are early warnings of the days to come,” he said. “Surviving this storm will be a test of endurance, teamwork, common sense and patience.”

12,000 in shelters

Cooper requested additional federal disaster assistance in anticipation of what his office called “historic major damage” across the state.

Michael Nelson floats in a boat made from a metal tub and fishing floats after the Neuse River went over its banks and flooded his street during Hurricane Florence in New Bern, N.C., Thursday. The homes of about 10 million were under watches or warnings for the hurricane or tropical storm conditions. (Chip Somodevilla/Getty Images)

More than 80,000 people were already without power as the storm began buffeting the coast, and more than 12,000 were in shelters. Another 400 people were in shelters in Virginia, where forecasts were less dire.

Prisoners were affected, too. North Carolina corrections officials said more than 3,000 people were relocated from adult prisons and juvenile centres in the path of Florence, and more than 300 county prisoners were transferred to state facilities.

Watch this video about the science behind Hurricane Florence:

Officials said some 1.7 million people in the Carolinas and Virginia were warned to evacuate, but it’s unclear how many did. The homes of about 10 million were under watches or warnings for the hurricane or tropical storm conditions.

The Canadian government has warned citizens against travel to the stretch of the U.S. East Coast that is expected to be hammered by Florence.

9-metre waves

Spanish moss waved in the trees as the winds picked up in Wilmington, and floating docks bounced atop swells at Morehead City. Ocean water flowed between homes and on to streets on the Outer Banks. Waves crashed against wooden fishing piers.

Jamie Thompson walks through flooded sections of East Front Street near Union Point Park in New Bern, N.C. Forecasters said conditions will deteriorate throughout Friday. (Gray Whitley/Sun Journal via AP)

Coastal towns in the Carolinas were largely empty, and schools and businesses closed as far south as Georgia.

A buoy off the North Carolina coast recorded waves nearly nine metres high as Florence churned toward shore.

90 cm of rain possible

Forecasters said conditions will deteriorate as the storm pushes ashore near the North Carolina-South Carolina line and makes its way slowly inland. Its surge could cover all but a sliver of the Carolina coast under as much as 3.4 metres of ocean water, and days of downpours could unload more than 90 centimetres of rain, touching off severe flooding.

Once a Category 4 hurricane with winds of 225 km/h, the hurricane was downgraded to a Category 1 on Thursday night.

Forecasters said that given the storm’s size and sluggish track, it could cause epic damage akin to what the Houston area saw during Hurricane Harvey just over a year ago, with floodwaters swamping homes and businesses and washing over industrial waste sites and hog-manure ponds.

The hurricane was seen as a major test for the country’s Federal Emergency Management Agency, which was heavily criticized as slow and unprepared for Hurricane Maria in Puerto Rico last year.

Trump says FEMA ‘supplied and ready’

As Florence drew near, U.S. President Donald Trump tweeted that FEMA and first responders are “supplied and ready,” and he disputed the official conclusion that nearly 3,000 people died in Puerto Rico, claiming the figure was a Democratic plot to make him look bad.

Not everyone was taking Florence too seriously: About two dozen locals gathered Thursday night behind the boarded-up windows of The Barbary Coast bar as Florence blew into Wilmington.

“We’ll operate without power; we have candles. And you don’t need power to sling booze,” said owner Eli Ellsworth.

Others were at home hoping for the best.

“This is our only home. We have two boats and all our worldly possessions,” said Susan Patchkofsky, who refused her family’s pleas to evacuate and stayed at Emerald Isle with her husband. “We have a safe basement and generator that comes on automatically. We chose to hunker down.”

With files from CBC News