Blowing and drifting snow in Chicago forced the cancellation of at least 460 flights and may tie up commuters.United Continental Holdings Inc., the world’s largest carrier, canceled 200 flights at O’Hare International Airport, said Mary Ryan, a spokeswoman for the Chicago-based company. Southwest Airlines Inc. canceled 100 from Midway International Airport, while American Airlines and its American Eagle regional carrier scrubbed 166, according to e-mails from the airlines.

The heaviest snow will fall later today and accumulations may reach 8 inches in the Chicago area, said Charles Mott, a National Weather Service meteorologist in Romeoville, Illinois.The winds are going to increase, too, late this afternoon or evening, making the rush hour interesting, Mott said by telephone.The weather service has issued winter storm warnings and advisories stretching across the Midwest and extended them in the Appalachian Mountains.

A winter weather advisory means falling snow will make travel difficult. A winter storm warning means significant snowfall is expected and travel will be dangerous. The weather service advises limiting travel to emergencies and keeping a flashlight, food and water in vehicles.Mott said this is the first significant snowfall for Chicago in what has been a mild winter. As much as 14 inches may fall in northern Indiana, according to the weather service.The storm is expected to track across the Great Lakes and into southern Ontario, Mott said.

Snow in Toronto

Toronto is expected to get light snow and rain late today and tomorrow, according to Environment Canada’s forecast. Freezing rain warnings have been issued for the eastern end of Lake Ontario, including Kingston, Ontario.A winter weather advisory has been issued on the U.S. side of Lake Ontario, including Buffalo, New York, and an ice-storm warning has been issued for northern New York from Watertown to Massena, according to the U.S. weather service.Two to 4 inches of snow is expected in Buffalo tomorrow and Detroit may receive 2 inches. In addition to the Midwest storm, heavy snow is also falling across the northern New England states of Vermont, New Hampshire and Maine.As much as 8 inches of snow and 2 inches of sleet may fall by tomorrow in Berlin, New Hampshire, about 150 miles north of Boston.