UNITED STATES -   Airlines have preemptively canceled about 3,000 flights as major winter takes aim at the East Coast. Blizzard warnings and up to two feet of snow are forecast for major cities like Washington and Baltimore while mid-Atlantic cities like Charlotte could be grounded by ice. About 1,800 Friday flights had been canceled as of Thursday evening. More than 650 of those were at Charlotte,  where American said it would preemptively ground its entire schedule Friday ahead of icy and wintry weather there. Charlotte is American's second-busiest hub, and shutting it down for an entire day is sure to send disruptions around American's nationwide network.

American also planned to suspend its entire Saturday schedule at Philadelphia, Washington National, Balitmore/Washington and Washington Dulles. Philadelphia and Washington National are two of American's most important hubs.

Beyond American, cancellations were hitting other airports. More than 250 flights -- or close to half of the entire's day schedule -- was grounded at Baltimore/Washington International (BWI). Another 250 were preemptively canceled at Raleigh/Durham, where that figure represented more than half of the day's schedule there.

Dozens of Friday cancellations were being reported Thursday evening at many other airports, including Washington Reagan National, New York LaGuardia, Atlanta, Dallas/Fort Worth, Washington Dulles, Chicago O'Hare and Chicago Midway.

Heavy snowfall and generally adverse winter weather are likely to result in moderate to severe travel disruptions, including further cancellations or delays to other airlines and services. It should be noted that despite the anticipated resumption of normal operations, further flight delays are likely due to the resultant backlog. Additionally, demands for other modes of transport or other airline carriers should be anticipated.