(CNN) -- Latest developments:
• More than 4,600 flights scheduled for Thursday and Friday have been canceled due to the storm menacing the East Coast, the flight tracking website flightaware.com reported around 7 a.m. ET on Friday. There are roughly an equal number called off Friday and preemptively for Saturday.
• The National Weather Service's blizzard warning now includes Philadelphia and New York City, which had been under a less dire blizzard watch. This means that "severe winter weather conditions" -- falling and blowing snow, strong winds and whiteout conditions -- "are expected or occurring."
• Snow is covering roads in and around several major cities in North Carolina, including Asheville and Greensboro. The local National Weather Service office said the state's Research Triangle, which includes Raleigh, Durham and Chapel Hill, will see a mix of snow and sleet Friday morning, with sleet and freezing rain expected in the afternoon.
• Washington, D.C., is forecast to start getting snow late Friday afternoon and then get hit hard that night, when 10 to 14 inches of snow could fall. Another 9 to 13 inches is possible Saturday before the precipitation wraps up sometime after midnight. The snow will be accompanied by sustained winds of up to 30 mph and gusts of 10 or more miles per hour stronger than that.
The next government shutdown is coming soon -- compliments of a snowstorm. Around noon, federal agencies will shutter ahead of a blizzard headed for Washington.
But that's a minor moment in the massive winter storm raking over at least a dozen states with 75 million people in its path. It will dump 2 feet or more on the capital, then it will take similar fury up to the Northeast at least as far as New York City.
It has already begun paving an icy blotch of freezing rain, sleet or snow from Little Rock, Arkansas, through the Mid-Atlantic while stirring trouble as far south as Florida.
"There's more to this storm than just the snow and ice that we're predicting," said CNN meteorologist Derek Van Dam. Along its southernmost fringes, it could throw down thunderstorms and large hail.
Even tornado watches spread across the Gulf Coast.
States of emergency have been called in Pennsylvania, Tennessee, Maryland, Virginia and North Carolina, and they stretch as far south as the northernmost counties of Georgia.
Washington worst case
On Thursday, a dusting of snow during morning rush hour caught Washington off guard.
When motorists drove over it, the snow packed down and froze solid, turning streets into parking lots. Some drivers abandoned their cars, leaving them stranded.
Homeland Security is worried that things could get much worse. "There are predictions going off the map for it," emergency management spokesman Chris Geldart told CNN's John Vause
By Sunday, Washington could break its all-time snow record. Twenty-eight inches fell in the "Knickerbocker Storm" of 1922, named after a theater that collapsed under the weight of snow, killing 100 people.
With the weight of so much snow falling at once over the weekend, "we're concerned that we will perhaps get some collapsed roofs," Geldart said.
Ice and snow could snap tree limbs, downing electrical lines. "It is a very real chance that we are going to see some very high numbers for power outages," Geldart said.
Big snow dump
The blizzard is expected to hit Baltimore just as hard. The heaviest snow warning from the National Weather Service covers more than 15 counties in the region.
Moving outside the storm's Washington-Baltimore bull's-eye, snow will pile up a foot or two in eastern Kentucky, West Virginia, Virginia, southern Pennsylvania and New Jersey, the CNN Weather Center said.
Philadelphia and New York City were placed under blizzard warnings early Friday. Before the storm's path began to firm up, at least one prediction model said the storm might veer over the Atlantic and spare much of the Northeast the worst.
Virginia also got a dangerous preview Thursday, when cars slid off course, and police untangled 767 accidents and tended to 392 stalled motorist calls. A man died in Maryland, when a snowplow hit him.
Virginia Gov. Terry McAuliffe has called out 500 National Guard members to face the coming storm. "We have the equipment, we have the folks, they're mobilized, they're ready. We've been out for 24 hours. We like to get out early," he told CNN affiliate WJLA.
Residents have wiped supermarket shelves clean of basic staples like milk, bread and beer.
Heaters, shovels and sleds sold at a frenzied pace in Silver Spring, Maryland. Ice melt chemical, too.
"They know (the storm is) coming," Roy Washington, a manager at Strosniders Hardware, told WJLA. "They hear the forecast, and they want to be prepared for it."
Ahead of the storm's arrival on the East Coast, airlines have canceled more than 4,600 flights, and anticipated troubles at regional airports are resulting in flight delays and cancellations elsewhere in the country.
United Airlines announced it would suspend flights at its Washington Dulles International Airport hub and other Mid-Atlantic airports starting Friday afternoon.
Amtrak also announced a modified schedule in the Northeast because of the storm, and Washington said its Metrorail system would close all day Saturday and Sunday.
"This is not a storm that anyone should take lightly, and I would urge all residents to plan to get to a safe place before the storm arrives Friday afternoon," said Metro CEO Paul J. Wiedefeld.
At Reagan International Airport near Washington, long lines formed as people got out of town early. Airport workers prepped for the looming blizzard.
"We're checking our chemical levels, our equipment, and also calling in our snow removal teams," said Washington airports spokeswoman Kimberly Gibbs.
And farther south, a mix of wintry precipitation is icing a swath from eastern Arkansas through Tennessee, Kentucky, north Georgia and the Carolinas.
Tennessee was hit early, and a 19-year-old man died Wednesday after his car slid off a road "due to weather and speeding," authorities said. Two people died in North Carolina late Wednesday in crashes along snow-covered roads.
In Charlotte, North Carolina, host to the NFC professional football championship on Sunday, the North Carolina Panther Pride parade was canceled.
And American Airlines nixed some flights in and out of the city ahead of the storm, which is expected to dump freezing rain there.
The Panthers face the Arizona Cardinals in the championship.
Some Arizona fans took flights early to beat any cancellations, AZ Central reported. But the team has not changed travel plans and will be on a Delta Air Lines flight out of Phoenix late Saturday.
North Carolina Gov. Pat McCrory said his state is doing "everything we can" to ensure public safety if worst-case scenarios come true. Several schools, churches and courts around North Carolina had been ordered closed Friday.
"Our goal with this potential winter storm ... is to be overprepared and hopefully underwhelmed," McCrory said.