The storm, which complicated travel and busted plans for the three-day weekend across much of the country, caused problems from Kansas, where the governor declared an emergency, to New England, where forecasters predicted up to 2 feet of snow and warned of avalanches.

The fallout was bleak: Flights canceled by the thousands, extensive power failures and stern warnings to stay off the roads in cities like Chicago.

At midday Saturday, the heaviest snow stretched from northern Illinois into Ohio and southern Michigan, according to Rich Otto, a National Weather Service meteorologist. To the west, where the storm had hit Friday, more than 1 foot had been recorded in parts of South Dakota, Minnesota and Iowa.

As the storm sped eastward, where it is forecast to worsen, Otto said he expected most of the snow to fall in a band from northern Pennsylvania through central New York and into New England’s inland areas. Other places, especially those to the south and closer to the coast, were expected to get a wintry cocktail of snow, sleet, rain and ice, followed by plummeting temperatures.

The storm continued to move briskly and was not expected to linger in the Northeast. Otto said he expected the worst to move past New York City, where only 2 or 3 inches were forecast, by Sunday morning. In New England, the storm was expected to pass by Sunday night.

The snowstorm’s impact has proved frightening, especially on transportation.

A United Airlines plane slid off a concrete surface at Chicago O’Hare International Airport on Saturday, while the plane was turning off a runway. Airline officials said no injuries were reported.

The night before, at Eppley Airfield in Omaha, a Southwest Airlines plane slid off the runway after landing.

In Kansas, the state Department of Transportation said one of its drivers died Saturday morning in a crash south of Kansas City.

More than 3,200 flights have been canceled so far, according the flight tracking site FlightAware.