A winter storm headed east Friday after pounding the Plains and Midwest with more than a foot of snow, causing holiday travel chaos with hundreds of canceled flights and closed roads, NBC News reported. Across the country, 532 flights had been canceled and 3,757 delayed Friday through late morning, according to FlightStats.com. Most of those were in Boston, Chicago, Detroit, Philadelphia and the New York area. The storm, which has been blamed for at least seven deaths, caused blizzard conditions and even spawned a twister in Mobile, Ala. The National Weather Service issued numerous warnings of potentially dangerous weather, with winds in much of the Northeast gusting as high as 60 mph. Flood and high-wind warnings have been issued for parts of New York, New Jersey, Pennsylvania, Connecticut and Massachusetts. The storm, part of a system that began in the Rockies earlier in the week, led airlines to cancel more than 1,000 flights and caused whiteout conditions that left roads dangerous to drive on.