
At least 25 million residents on the East Coast are at risk from Hurricane Florence which is expected to deliver a 'direct hit' this week, bringing 157 mph winds, devastating flooding and even the threat of a tainted water supply.

The 'life-threatening' hurricane has sparked mass evacuations with as many as 1.5 million people warned to seek shelter from the potentially catastrophic storm, while five million are under a direct hurricane warning.

CNN said more than 25 million people are in the 'forecast cone' from the storm though strong winds and flooding could hit even more people.

'This will likely be the storm of a lifetime for portions of the Carolina coast,' the National Weather Service said.

Florence was upgraded to a Category 4 hurricane on Tuesday and was packing deadly winds of 130 miles per hour, but it is expected to strengthen and turn into 'an extremely dangerous major hurricane' on Thursday night before making landfall.

The Federal Emergency Management Agency said the biggest danger was the storm surge - a wall of water from the sea which could reach 20ft high. Some areas could get deluged with 20 inches of rain.

At least 25 million residents on the East Coast are at risk from Hurricane Florence which is expected to deliver a 'direct hit' this week

People evacuate ahead of the forecasted landfall of Hurricane Florence as they seek shelter at Emma B. Trask Middle School in Wilmington, North Carolina, USA

Chuck Ledford (L), watches Looney-Tunes with his daughter Misty as they evacuate ahead of the forecasted landfall of Hurricane Florence as they seek shelter at Emma B. Trask Middle School in Wilmington,

The category four storm could be the strongest to strike the Carolina coast since Hurricane Hugo in 1989

The 'life-threatening' has sparked mass evacuations with as many as 1.5 million people warned to seek shelter from the potentially catastrophic storm, while five million are under a direct hurricane warning

'Storm surge has the highest potential to kill the most amount of people,' FEMA Administrator Brock Long told CNN. 'It also has the highest potential to cause the most destruction.'

FEMA said Florence is the strongest storm to hit the Carolinas and Virginia region 'in decades.'

'We cannot stress the importance to our citizens that are in evacuations to heed the local and state warnings,' added Jeffrey Byard of FEMA at a news conference.

'Hurricane Florence is the strongest storm to target the Carolinas and this part of our country in decades.'

Byard said that they are bracing for 'massive damage,' power outages and even fatalities.

'This storm will and has the potential to cause loss of life, and we cannot emphasize the importance to take action now,' said Byard.

On Tuesday night, the storm was about 350 miles southwest of Bermuda and is moving northwest, according to the National Hurricane Center.

Allison Violette, a resident of Fayetteville, North Carolina, told NBC that she and her husband were moving all their belongings to the second floor of their home in preparation for the hurricane.

She said they had learned their lesson after Hurricane Matthew flooded the house in 2016.

At least 25 million residents on the East Coast are at risk from Hurricane Florence which is expected to deliver a 'direct hit' this week

'It's devastating to walk into your house and have seen it flooded, and to lose everything. And to think that can happen again, I just don't, I just don't want to have that. And so anything I can save that's meaningful for us, I want to save it,' she said.

'I don't know if we would want to do that again, and experience it. It's just life-changing,' said her husband Cal Violette.

Hog farmers along the East Coast are also scrambling to drain their waste pools ahead of the storm. Hog farms each have open-air 'lagoons' filled with manure - which turn bright pink due to the bacteria festering in the lagoons.

If the rivers break their banks, or lagoons overflow, affecting local waterways, which could damage to local environment and put drinking water sources and public health at risk.

Flooding could also lead to the deaths of thousands of animals if they cannot be evacuated in time.

Marlowe Vaughan of Ivy Spring Creek Farm in Goldsboro, has spent most of day pumping liquid waste from her lagoons to make more room for incoming rainfall.

'We try to pump down as much as we can, but after that, it's kind of in God's hands. We're kind of at the mercy of the storm.'

On Tuesday, motorists streamed inland on highways converted to one-way routes and supermarket shelves were stripped bare as more than 1 million people in North Carolina, South Carolina and Virginia were ordered to flee their homes as the hurricane churns across the Atlantic Ocean towards the coast.

Marine Corps Recruit Depot Parris Island, S.C., prepare to evacuate to Marine Corps Logistic Base Albany following an evacuation order directed by Brig. Gen. James Glynn, the depot's commanding general, Tuesday

Dorothy Pope, 78, and her sister Clydie Gardner, 71, settle in to the home they share in Princeville, N.C., after a normal grocery run on Tuesday. They are keeping an eye on the storm but have no plans to leave unless they are threatened by flooding

A store's bread shelves are bare as people stock up on food in Myrtle Beach, South Carolina on Tuesday ahead of the arrival of Hurricane Florence

People drive over a drawbridge in Wrightsville Beach, N.C., as they evacuate the area in advance of Hurricane Florence

More than 1.5 million people were ordered to evacuate their homes in preparation. Vehicles lined up in heavy traffic (above) in Wallace, North Carolina on Tuesday

Rob Quinn boards up Lagerheads Tavern in Wrightsville Beach, North Carolina after 300,000 people were ordered to evacuate the state's coastal areas

Walker Townsend (right) and Dalton Trout (center) fill sand bags in Isle of Palms, South Carolina on Monday as the state's entire coastline was ordered to prepare for mandatory evacuations

Don Parrish, on vacation with his wife Barbara, from Finely Ohio, talks about his plans to ride out Hurricane Florence in his vacation rental in Kill Devil Hills in the Outer Banks of North Carolina on September 11

'This storm is going to be a direct hit,' added Byard.

Forecasters and politicians pleaded with the public to take the warnings seriously and minced no words in describing the threat for what could become one of the most catastrophic hurricanes to hit the Eastern Seaboard in decades.

Despite the evacuation order, South Carolina Department of Corrections decided not to remove inmates at the Ridgeland Correctional Institution.

SCDC spokesman Dexter Lee said: 'In the past, it's been safer to leave them there'.

'This storm is a monster. It's big and it's vicious. It is an extremely, dangerous, life-threatening, historic hurricane,' said North Carolina Gov. Roy Cooper.

'The waves and the wind this storm may bring is nothing like you've ever seen. Even if you've ridden out storms before, this one is different. Don't bet your life on riding out a monster.'

South Carolina Gov. Henry McMaster, who issued a mandatory medical evacuation of 177 hospitals and medical facilities in his state said: 'We know the evacuation order I'm issuing will be inconvenient.

'But we're not going to gamble with the lives of the people of South Carolina. Not one.'

Sailors cast off mooring lines to the Command hospital ship USNS Comfort as the ship evacuates Naval Station Norfolk in preparation for Hurricane Florence in Norfolk, Virginia

In anticipation of the arrival of Hurricane Florence, sailors of Helicopter Sea Combat Squadron (HSC) 28 prepare MH-60S Sea Hawk helicopters to evacuate Naval Station Norfolk to ensure personnel safety and prevent damage to Navy assets on September 11

Greg Cook carries belongings to a van as he evacuates days before the arrival of Hurricane Florence at Wrightsville Beach, North Carolina on September 11

Employees of Redix board up the front windows of the store in Wrightsville Beach, N.C., Tuesday, Sept. 11

People evacuate ahead of the forecasted landfall of Hurricane Florence as they seek shelter at Emma B. Trask Middle School in Wilmington, North Carolina

People evacuate ahead of the forecasted landfall of Hurricane Florence as they seek shelter at Emma B. Trask Middle School in Wilmington, North Carolina

A Walmart in Mt. Pleasant, S.C, is closed, and barricaded, after Gov. Henry McMaster ordered a mandatory evacuation

Several interstates will close from Wednesday as will state offices — including the University of South Carolina — and schools across 26 counties in the eastern part of the state. Some schools will be used as evacuation shelters officials said Monday.

'We don't want the school children in harm's way,' McMaster told The State. We know it's going to hit somewhere where it's going to have a dramatic impact on South Carolina. We're going to get a whole lot of water that we haven't seen in some time.'

McMaster previously issued a mandatory medical evacuation of 177 hospitals and medical facilities, including nursing homes, in the eight coastal counties.

North and South Carolina and Virginia have all ordered mass evacuations along the coast after declaring states of emergency.

Virginia issued a mandatory evacuation order for about 245,000 residents in flood-prone coastal areas beginning at 8am.

At least 250,000 more people were due to be evacuated from the northern Outer Banks in North Carolina on Tuesday after more than 50,000 people were ordered on Monday to leave Hatteras and Ocracoke, the southernmost of the state's barrier islands.

Getting out of harm's way could prove difficult and officials are already predicting the financial toll could reach $30 billion.

Sandbags sit in doorways as water floods outside buildings in Old Town Alexandria, Virginia on September 11

People cross the street as water floods outside buildings in Old Town Alexandria, Virginia on September 11, where more than a million people were under evacuation orders in the eastern United States Tuesday

Florence is so wide that a life-threatening storm surge was being pushed 300 miles ahead of its eye, and so wet that a swath of states from South Carolina to Ohio and Pennsylvania could get deluged.

People across the region rushed to buy bottled water and other supplies, board up their homes or get out of town.

A line of heavy traffic moved away from the coast on Interstate 40, the main route between the port city of Wilmington and inland Raleigh.

Between the two cities, about two hours apart, the traffic flowed smoothly in places and became gridlocked in others because of fender-benders.

Only a trickle of vehicles was going in the opposite direction, including pickup trucks carrying plywood and other building materials. Service stations started running out of gas as far west as Raleigh, with bright yellow bags, signs or rags placed over the pumps to show they were out of order.

Florence could hit the Carolinas harder than any hurricane since Hazel packed 130 mph winds in 1954. That Category 4 storm destroyed 15,000 buildings and 19 people in North Carolina. In the six decades since then, many thousands of people have moved to the coast.

The pumps at the Shell gas station on Western Boulevard featured 'out of gas' signs as people prepared to ride out Hurricane Florence on Tuesday

A gas station in Mt. Pleasant S.C. alerts motorist that it is out of gas due to the heavy demand caused by Hurricane Florence

Tarek Elshik, left, fills gas cans to fuel a generator to refrigerate insulin for his 10-year-old daughter Yasmeen Elshik's Type 1 diabetes treatment in case power goes out during Hurricane Florence

Food Lion employee Greg Partin helps a customer to her car on Monday, Sept. 10, 2018 at the Woodcroft shopping center in Durham, N.C

Wood boards and cardboard boxes block the entrance to a Walmart store in Kill Devil Hills in the Outer Banks of North Carolina on September 11

A man uses a drill to install storm shutters on a home in Kill Devil Hills in the Outer Banks of North Carolina on September 11

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.

Authorities warned of life-threatening coastal storm surges and the potential for Florence to unleash prolonged torrential rains and widespread flooding, especially if it lingers inland for several days.

National Hurricane Center Director Ken Graham warned of 'staggering' amounts of rainfall that may extend hundreds of miles inland and cause flash flooding across the mid-Atlantic region.

'This one really scares me,' Graham said.

The US military said it was sending an advance team to Raleigh, North Carolina, to coordinate with federal and state partners. The US Navy also ordered 30 warships out to sea from their port at Naval Station Norfolk in Virginia.

For many people, the challenge could be finding a safe refuge: If Florence slows to a crawl just off the coast, it could bring torrential rains 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 don't usually get much tropical weather.

'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 probably not as prepared as everybody would like,' said Craig Fugate, former director of the Federal Emergency Management Agency.

The storm's potential path also includes half a dozen nuclear power plants, pits holding coal-ash and other industrial waste, and numerous hog farms that store animal waste in massive open-air lagoons.

Airlines, including American, Southwest, Delta and JetBlue, have begun letting affected passengers change travel plans without the usual fees.

Amtrak trains are also being canceled or face schedule modifications from Wednesday to Sunday. The company is also waiving charges for reservation changes.

A warm ocean is the fuel that powers hurricanes, and this area of the ocean is seeing temperatures peak near 85 degrees (30 Celsius), hurricane specialist Eric Blake wrote. And with little wind shear to pull the storm apart, Florence's hurricane-strength winds were expanding.

'Unfortunately, the models were right. Florence has rapidly intensified into an extremely dangerous hurricane,' Blake wrote Monday evening, predicting that the hurricane's top sustained winds would approach the 157 mph threshold for a wost-case Category 5 scenario.

Tuesday morning's forecast still supports this, the National Hurricane Center said.

By 5am Tuesday, Florence was centered about 975 miles east-southeast of Cape Fear, North Carolina, and moving west-northwest at 15 mph. Its center will move between Bermuda and the Bahamas on Tuesday and Wednesday and approach the coast of South Carolina or North Carolina on Thursday.

Russell Meadows, left, helps neighbor Rob Muller board up his home ahead of Hurricane Florence in Morehead City, N.C

Larry Lynch selects a can of Armour Vienna Bites while grocery shopping in preparation for Hurricane Florence on Tuesday

Irene McNeil selects canned vegetables while grocery shopping in preparation for Hurricane Florence

A treasure hunter uses his metal detector on the beach in front of the surf before Hurricane Florence comes ashore

Two other storms were spinning in the Atlantic. Hurricane Isaac was expected to lose strength as it reaches the Caribbean, and Helene, much farther out to sea, may veer northward into the open ocean as the 2018 hurricane season reaches its peak.

In the Pacific, Hurricane Olivia triggered warnings for multiple Hawaiian islands, blowing westward and expected to arrive in the state as soon as late Tuesday or early Wednesday.

'Please be prepared, be careful and be SAFE!' President Donald Trump tweeted Monday evening.

He added on Tuesday it would be 'tremendously big, and tremendously wet.'

'The safety of the American people is my absolute highest priority. We are sparing no expense. We are totally prepared, we're ready, we're as ready as anybody's ever been,' Trump said.

'The places that are in the way and in the most jeopardy would be Virginia, North Carolina, South Carolina, that area. They haven't seen anything like what's coming at us in 25, 30 years, maybe ever. It's tremendously big and tremendously wet,' he added. 'Tremendous amounts of water.'

Just months ago, disaster planners simulated a Category 4 hurricane strike alarmingly similar to the real-world scenario now unfolding on a dangerously vulnerable stretch of the East Coast.

A fictional 'Hurricane Cora' barreled into southeast Virginia and up the Chesapeake Bay to strike Washington, D.C., in the narrative created by the Federal Emergency Management Agency and Argonne National Laboratory.

The result was catastrophic damage, which has some experts concerned that Hurricane Florence could produce a disaster comparable to 2005's Hurricane Katrina and in a part of the country that is famously difficult to evacuate.

The simulated hurricane knocked out power for most gas stations in the Mid-Atlantic region, damaged a nuclear power plant and sent debris into major shipping channels, among other problems, according to a Department of Energy simulation manual.

'What they were trying to do was create a worst-case scenario, but it's a very realistic scenario,' said Joshua Behr, a research professor at Virginia's Old Dominion University who is involved in disaster modeling and simulations.

Senior leaders from the White House, along with more than 91 federal departments and agencies, participated in the 'national level exercise' in late April and early May, FEMA said.

U.S. President Donald Trump speaks during an Oval Office meeting on hurricane preparations for Hurricane Florence at the White House in Washington, U.S., September 11

The fictional storm made landfall in the heavily populated Hampton Roads region, bringing a 15-foot storm surge and up to 9 inches of rain to some areas within the first six hours. That cut off main routes - used for escape as well as for rescuers - in the Hampton Roads area and elsewhere.

In the scenario, Cora also slammed hurricane-force winds into three nuclear power stations. One was damaged. Thirty-three major power substations were at risk from storm surge and major flooding.

Key roads and bridges were also damaged, and debris blocked the Newport News Channel and other waterways. Coast Guard Station Cape Charles lost power, and Coast Guard Station Chincoteague was severely damaged by high winds. The ferocious fictional storm also damaged and closed Reagan National Airport in Washington.

The make-believe hurricane threatened hundreds of cell towers, and the area where power was knocked out included 135 data centers in Virginia and another 60 in Maryland.

The Cora scenario projected hurricane-force winds inflicting 'catastrophic damage' to homes and significant damage to critical infrastructure within a 50-mile radius of the hurricane's center.

The manual makes no mention of deaths and injuries, focusing instead on infrastructure.

Another striking similarity between the scenario and Hurricane Florence's path: already saturated ground on that part of the Mid-Atlantic coast.

'What I fear is that saturation, combined with a storm that kind of stalls out,' said Behr, who has studied vulnerable populations in the paths of Hurricane Katrina on the Gulf Coast and in the Hampton Roads region.

If parts of the East Coast are deluged with water, it could result in a catastrophe on the scale of Katrina, Behr said. And recovering from a disaster in the Hampton Roads region would also parallel Katrina's aftermath, he added.

'I believe that those patterns are also going to manifest in Hampton Roads if and when a large storm hits,' he said. 'The vulnerability of our populations are quite similar to New Orleans. Displacement, pain, suffering, property loss. All those things are going to play out in a fashion that has parallels to how Katrina played out.'