The forecasted storm track covers a number of major airports -- including those in the Charlotte, Washington, Baltimore, Philadelphia and New York areas.
About 6,000 flights across the country scheduled for Friday and Saturday were canceled, the flight tracking website flightaware.com
reported Friday morning.
For example, airlines canceled all flights that were to depart or arrive Saturday at Philadelphia International Airport, the airport said.
The Washington area's Metrorail system
planned to suspend service from 11 p.m. Friday through Sunday, and the city's bus service was to stop from 5 p.m. Friday through the weekend.
The mayors of Washington and New York urged people to avoid roads during the storm.
"Get ready, get your supplies today," New York Mayor Bill de Blasio told CNN's "New Day" on Friday. "(Then) stay indoors, stay safe."
A lot of you are in its path
The storm system is expected to hit Friday and Saturday in areas where about 85 million live, from Arkansas eastward to the East Coast, and from the South to parts of the Midwest, the Mid-Atlantic, New York and southern New England.
Snowfall accumulations of at least 10 inches were possible for parts of Kentucky, eastern Tennessee, southern Ohio, North Carolina, West Virginia, Virginia, Maryland, southern Pennsylvania, northern Delaware, New Jersey and New York City.
As of Friday morning, blizzard warnings were in effect for Washington, Baltimore, Philadelphia and New York City, and watches were in place in nearby areas -- covering nearly 30 million people.
The Washington area could see about 24 inches of snow from Friday evening through Saturday, with potentially 28-mph winds (and gusts up to 38 mph), making for poor visibility.
Even more snow -- up to 30 inches -- was possible just to the west, in northern Virginia and parts of Maryland.
The Philadelphia area may have up to 14 inches.
There was more uncertainty for New York City -- up to 1 foot was expected as of Friday morning.
The city could see more if the storm tracks farther than expected to the north, or less if it goes south.
Record-breaker for Washington?
The nation's capital hasn't seen too many snowfalls of more than 17 inches in 130 years
, so this storm could be of historical significance.
The "Knickerbocker Storm" of 1922 dumped 28 inches and killed nearly 100 people when the roof of a theater by that name collapsed under the weight of snow.
More recently, there was "Snowmageddon"
-- the February 5-6 storm of 2010 that the National Weather Service says dropped 17.8 inches in the city. News reports at the time, however, said higher amounts -- about 25 inches -- were recorded at Washington's American University.
According to the National Weather Service, Washington has received only five snow events totaling more than 17 inches of snowfall over a maximum three-day period since record-keeping began in 1884.
Ice could leave many without power
Snow won't be the only problem in the South.
Ice accumulation is a major concern in two chunks of the south: an area covering parts of Arkansas, Tennessee and Kentucky, and one including northeast Georgia, the Carolinas and parts of Virginia.
Up to 1 inch of ice accumulation is possible from northeast Georgia into the Carolinas. That's potentially terrible news for drivers, and the weight of the ice can snap power lines or bring down trees that will do the same.
Charlotte and Raleigh, North Carolina, and Greenville and Spartanburg, South Carolina, were among the cities with significant ice accumulation possible.
Severe thunderstorms and even tornadoes also were possible Friday in eastern Texas and parts of Louisiana and Mississippi.
, a Department of Homeland Security website, offers tips
on what to do before and during winter storms to keep safe.
These include having certain emergency supplies
The Centers for Disease Control and Prevention also offers online checklists
on how to prepare your home and car for storms.