What to Know Hurricane Florence is expected to hit the Carolinas at the end of the week as a Category 4 hurricane

The system is forecast to move inland and dump rain on the D.C. area for up to six days

States of emergency are in effect for D.C., Maryland and Virginia.

Motorists streamed inland on highways converted to one-way evacuation routes Tuesday as about 1.7 million people in three states were warned to get out of the way of Hurricane Florence, a hair-raising storm taking dead aim at the Carolinas with 140 mph winds and potentially ruinous rains.

The latest models show a southbound trend that takes the Washington, D.C., region out of the most serious impact zone, but Storm Team4 is tracking up to six days of rain that could cause flooding.

News4's Jim Handly reports from North Carolina. Many residents have evacuated, but others are wondering if they should ride out the storm.

If Hurricane Florence’s path changes, serious rain, flooding and winds could hit the Washington metro area, prompting officials in Maryland, D.C. and Virginia to prepare for the worst.

Eighty first responders with Maryland Task Force One had truckloads of gear, including boats, rescue supplies, cases of water and packed suitcases, ready to go when they got the directions to head to South Carolina. They leave Wednesday morning at 6 a.m.

An unusual combination of other weather systems are likely to stall Florence when it hits the Carolinas, allowing it to sit for days and dump huge amounts of rain on several states.

"The longer it stays, the more wind, the more rain. That means the more trees that could fall, the more power outages," National Hurricane Center Director Ken Graham said.

At 11 p.m., the storm was centered 670 miles southeast of Cape Fear, North Carolina, moving at 17 mph. It was a potentially catastrophic Category 4 storm but was expected to keep drawing energy from the warm water and intensify to near Category 5, which means winds of 157 mph or higher.

Rain, Floods Threaten D.C. Area

Storm Team4 continues to track heavy rain and floods and advises those in normal areas of flooding to prepare for more.

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The good news on Tuesday is that Hurricane Florence will likely be blocked from the D.C. metro region by the same area of high pressure that brought wet weather and floods during the weekend and early week. Areas farther south in Virginia, from Roanoke to Danville to Farmville, are still in line to be slammed with 10 to 15 inches of rain.

"People need to take heed, take precautionary steps now," Chief Scott E. Goldstein told News4. "Hurricane Florence is a very formidable enemy. A very dangerous storm."

Waterfront areas in the metro area, including Georgetown and Alexandria, have been grappling with flooding since Sunday. The

Coastal flood advisories are already in effect into Wednesday morning for parts of Anne Arundel, Arlington and St. Mary’s counties and Washington, D.C., Alexandria and Falls Church.

Flood warnings extend into Wednesday for Virginia counties of Loudoun and Fairfax and Maryland counties of Frederick and Montgomery.

How Much Rain Florence May Bring

This map shows how much rain is expected to fall within seven days.

Storm Team4 is tracking rain from Hurricane Florence beginning late Thursday or early Friday. Rains could hover for between four and six days, dropping 3 to 4 inches of rain on the area. Flooding and downed trees are the biggest concerns. Less rain could be seen to the north; to the south, Virginia is preparing for dangerous weather.

Evacuation Ordered in Virginia

President Donald Trump declared states of emergency for North and South Carolina and Virginia, opening the way for federal aid. He said the federal government is "absolutely, totally prepared" for Florence.

All three states ordered mass evacuations along the coast. Gov. Ralph Northam announced a mandatory evacuation that began Tuesday morning in Virginia for residents of low-lying coastal areas as state officials warned residents across the entire state to brace for a potential once-in-a-generation storm, catastrophic floods and days-long power outages.

Northam said the evacuation order applies to parts of the Hampton Roads area and Eastern Shore. State officials say 245,000 people live in the affected area. The evacuation order went into effect Tuesday at 8 a.m.

Northam said Virginia's evacuation zone includes the most flood-prone coastal areas. He said inland flooding could be severe and urged residents around the state to prepare for floods and loss of power.

"This is a serious storm and it's going to affect the entire state of Virginia," Northam said.

Potential Florence Storm Surge

This map shows how high the storm surge from Hurricane Florence has a 1 in 10 chance of reaching, measured in feet above ground and with the tide. Click a location to see the possible storm surge height there.

Virginia officials said they are taking several steps to prepare for the storm, including activating 1,500 National Guardsmen and asking other states to send rescue teams.

State officials said they have a tiered system for evacuating and are so far only requiring residents of the most flood-prone areas, known as "Zone A," to leave their homes.

The affected zone includes parts of Norfolk, Virginia Beach, Hampton and the Eastern Shore. It also stretches north to include parts of the Northern Neck and Middle Peninsula. A detailed map is available on the state's website.

The Virginia Department of Transportation is lifting temporary lane closures on major routes where possible, the agency said Tuesday. Express Lanes tolls in the Hampton Roads area have been suspended until further notice.

News4's David Culver is in Virginia, where the state is preparing for some towns to be slammed by Hurricane Florence.

State Coordinator for Emergency Management Jeff Stern said the state may order additional evacuations if the storm's projected path changes. The next tier of potential evacuees, Zone B, has about 300,000 residents.

Officials said they are continuing to work on details about where evacuees can seek shelter and additional details will be provided in the near term.

"The simplest answer is: go to higher ground and inland," Northam said.

State officials offered the following preparation tips:

Gather needed items for emergency kits for your home and vehicle. Virginia has tips on what to include for your family, home and pets online here.

Clear any debris from any drainage facilities on your property to prepare for heavy rain. You can find more about drainage in your neighborhood here.

Get your car road-ready and fill your gas tank for potentially lengthy travel in the event of an evacuation.

Virginia Department of Transportation workers began clearing drains Tuesday, which are waterlogged after a high level of rains.

Missing Attachment Storm Team4 meteorologist Tom Kierein has the forecast for Jan. 30, 2014.

Rainfall will be extremely heavy, dumping up to 10 to 20 inches over the next 7 days over much of North Carolina and Virginia, and even 30 inches in some places. Combined with high tides, the storm surge could reach 12 feet at the center of the storm, forecasters said Tuesday.

The size of Florence is "staggering," National Hurricane Center Director Ken Graham warned.

"We could cover several states easily with the cloud cover alone," Graham said. "This is not just a coastal event."

DC and Maryland in State of Emergency

D.C. Mayor Muriel Bowser on Tuesday joined Maryland and Virginia in declaring a state of emergency as the East Coast awaits the arrival of Hurricane Florence.

Mayor Muriel Bowser announced the move Tuesday morning, describing it as a necessary step to "ensure we have the resources and support" to handle several days of torrential rain.

Bowser said the District is anticipating flooding, heavy rain, wind and the possibility of power outages. She urged residents to prepare everything they need ahead of the storm.

Flooding is the biggest concern for the D.C. area in the days ahead: Florence is forecast to move inland and stall for several days, dumping rain on waterlogged ground.

D.C. officials say they will monitor conditions to determine whether they will need to deploy the levee on 17th Street NW for the first time.

Maryland Gov. Larry Hogan declared a state of emergency as a precaution on Monday afternoon.

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"At this time, there is still some uncertainty about the track of this storm and its potential impact, but we are preparing for any possible outcome, including the potential of historic, catastrophic and life-threatening flooding in Maryland," Hogan said. "Our state is taking every precaution, and I urge all Marylanders to do the same."

Travel Impacts

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

Charlotte, Raleigh, Wilmington: Residents of these cities are leaving home and many of them are headed to D.C. News4's Adam Tuss reports on the massive migration ahead of Hurricane Florence.

Only a trickle of vehicles was going in the opposite direction, including pickup trucks carrying plywood and other building materials.

Amtrak announced Tuesday that it will modify train service on several of its lines from Wednesday through Sunday. The Northeast Regional will suspend service south of D.C. starting Thursday, a spokeswoman confirmed to NBC Washington. See the latest information on Amtrak's website. Amtrak is waiving extra charges for riders who will need to change their trains.

D.C. area airports will see some delays and cancelations, even if the area isn't slammed, Metropolitan Washington Airport Authority spokesmen Rob Yingling said.

"Because we're talking about the East Coast, that will affect airports other than the one where the hurricane has the most direct effects," Yingling said.

He says American Airline flights rely on a Charlotte, North Carolina, hub.

Ongoing construction also poses a risk, and crews are sandbagging the area to hold the sites together.

Charleston International Airport in South Carolina is tweeting that it expects runways to close by midnight Wednesday as it monitors Hurricane Florence.

On many roads, crews are lifting lane closures to get drivers away from the coast.

Cancellations and Closures

As evacuation in the state got underway, the University of Mary Washington in Fredericksburg, Virginia, announced that it would be closing all of its campuses at 5 p.m. Wednesday. The university will reopen Monday morning.

Some festivals in the D.C. area, including the H Street Festival and Alexandria’s King Street Arts Fair, were rescheduled.

Hurricane Florence has forced the cancellation of several Top 25 games this weekend, including No. 13 Virginia Tech's home game against East Carolina, No. 14 West Virginia's trip to North Carolina State and No. 18 UCF's game at North Carolina.