CINCINNATI — A powerful winter storm system pounded the nation’s midsection Wednesday and headed toward the Northeast, where people braced for the high winds and heavy snow that disrupted holiday travel, knocked out power to thousands of homes and were blamed in at least six deaths.

Hundreds of flights were canceled or delayed, scores of motorists got stuck on icy roads or slid into drifts, and blizzard warnings were issued amid snowy gusts of 30 mph that blanketed roads and windshields, at times causing whiteout conditions.

“The way I’ve been describing it is as a low-end blizzard, but that’s sort of like saying a small Tyrannosaurus rex,” said John Kwiatkowski, a meteorologist with the National Weather Service in Indianapolis.

The system, which spawned Gulf Coast region tornadoes on Christmas Day, pushed through the Upper Ohio Valley and headed toward the Northeast. Forecasts called for 12 to 18 inches of snow from western New York into Maine. The storm left freezing temperatures in its aftermath, and forecasters also said parts of the Southeast from Virginia to Florida would see severe thunderstorms.

Schools on break and workers taking holiday vacations meant that many people could avoid messy commutes, but those who had to travel were implored to avoid it. Snow was blamed for scores of vehicle accidents as far east as Maryland, and about two dozen counties in Indiana and Ohio issued snow emergency travel alerts, urging people to go out on the roads only if necessary.

Some 40 vehicles got bogged down trying to make it up a slick hill in central Indiana, and four state snowplows slid off roads as snow fell at the rate of 3 inches an hour in some places.

Two passengers in a car on a sleet-slickened Arkansas highway were killed Wednesday in a head-on collision, and two people, including a 76-year-old Milwaukee woman, were killed Tuesday on Oklahoma highways. Deaths from wind-toppled trees were reported in Texas and Louisiana.

The day after a holiday wasn’t expected to be particularly busy for AAA, but its Cincinnati-area branch had its busiest Wednesday of the year.

By mid-afternoon, nearly 400 members had been helped with tows, jump starts and other aid, with calls still coming in, spokesman Mike Mills said.

Jennifer Miller, 58, was taking a bus Wednesday from Cincinnati to visit family in Columbus.

“I wish this had come yesterday and was gone today,” she said, struggling with a rolling suitcase and three smaller bags on a slushy sidewalk near the station. “I’m glad I don’t have to drive in this.”

Traffic crawled at 25 mph on Interstate 81 in Maryland, where authorities reported scores of accidents.

“We’re going to try to go down south and get below” the storm, said Richard Power, traveling from home in Levittown, N.Y., to Kentucky with his wife, two children and their beagle, Lucky.

He said they were well on their way until they hit snow in Pennsylvania, then 15 mph traffic on I-81 at Hagerstown. “We’re going to go as far as we can go. ... If it doesn’t get better, we’re going to just get a hotel.”

More than 1,200 flights were canceled by midday, according to FlightAware.com. Delays of more than an hour were reported Wednesday at the three New York City-area airports, the Federal Aviation Administration said.

In Arkansas, some of the nearly 200,000 people who lost power could be without it for as long as a week because of snapped poles and wires after ice and 10 inches of snow coated power lines, said the state’s largest utility, Entergy Arkansas. Gov. Mike Beebe sent out National Guard teams, and Humvees transported medical workers and patients.

Other states also had scattered outages. Duke Energy said it had nearly 300 outages in Indiana, with few left in Ohio by early afternoon after scores were reported in the morning.

As the storm moved east, New England state highway departments were treating roads and getting ready to mobilize with snowfall forecasts of a foot or more.

“People are picking up salt and a lot of shovels today,” said Andy Greenwood, an assistant manager at Aubuchon Hardware in Keene, N.H.

As usual, winter-sports enthusiasts welcomed the snow. At Smiling Hill Farm in Maine, Warren Knight was hoping for enough snow to allow the opening of trails.

“We watch the weather more carefully for cross-country skiing than we do for farming. And we’re pretty diligent about farming. We’re glued to the weather radio,” said Knight, who described the weather at the 500-acre farm in Westbrook as being akin to the prizes in “Cracker Jacks — we don’t know what we’re going to get.”