Pittsburgh ? As much as a foot of snow fell from the Plains across the Midwest on Saturday, snarling road and air travel, as the second big winter storm in a week barreled through on its way to New England.

Tens of thousands of people still lacked electricity after the first storm slammed Oklahoma, Kansas and Missouri earlier in the week. That storm was blamed for at least 38 deaths, mostly in traffic accidents.

Winter storm warnings and watches extended Saturday from Missouri across parts of Illinois, Indiana, Michigan, Ohio, Pennsylvania, New York, Vermont, New Hampshire and Maine, the National Weather Service said. As much as 15 inches of snow was forecast in parts of southern Michigan, with 10 inches possible in Detroit.

Snow started falling early in the afternoon in Pittsburgh, accumulating to about an inch before tapering off. Light rain and freezing rain took over later.

“We’ll have little bit of everything before the night is over,” said Bill Drzal, a Weather Service meteorologist in Pittsburgh.

Areas to the north and east of the city could see as much as 12 inches through tonight, according to the Weather Service.

More than 200 flights were canceled because of the weather Saturday at Chicago’s O’Hare International Airport, one of the nation’s busiest, and all other flights were delayed an hour, said Chicago Department of Aviation spokesman Gregg Cunningham.

Road travel also became tricky in northeastern Illinois, including Chicago’s suburbs, where officials reported spinouts and cars in ditches.

“It’s coming down steady,” said Mike Claffey, spokesman for the Illinois Department of Transportation.

Flakes were also falling by late Saturday in traditionally snow-prone Buffalo, N.Y. Accumulations of a foot or more were predicted for much of New York state.

Residents across New England packed stores to stock up before getting slammed. The winter weather days earlier caught many people unawares, stranding commuters and school buses as it made some of the nation’s busiest highways impassable.

Concern about the approaching storm led the University of Connecticut to cancel today’s winter commencement ceremony. About 850 undergraduates had expected to receive diplomas today, but school spokesman Richard Veilleux said officials were concerned about the safety of the students and their families and other guests on slippery roads.

Freezing rain was the culprit in the Plains days earlier, coating streets, windshields, tree limbs and power lines with ice as thick as an inch in Kansas, Oklahoma and Missouri.

Oklahoma, hardest hit by the earlier storm, got only cold, light rain early Saturday that turned into just a few inches of snow.

Officials in Oklahoma had worried the new snow could hamper power restoration efforts, but it turned out not to be a problem.