(NBC NEWS) A storm packing heavy, wet, travel-snarling snow threatened the Midwest on Tuesday with its hardest punch of the winter, and forecasters said it could curl through the major cities of the Northeast later this week.

Chicago expected up to a foot of snow, the most there since a blizzard in 2011. Almost 1,000 flights were canceled into and out of O’Hare and Midway airports before the sun came up. Minneapolis-St. Paul reported delays up to an hour.

The city of Chicago and the Illinois Tollway, a tangle of highways around the city, deployed their full fleets of snowplows, 466 in all. Dozens of school systems closed for the day. The evening rush hour was expected to be brutal.

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