A winter storm is hitting the Midwest with snow and wintry conditions, causing travel issues for many who were looking to get home following Thanksgiving. At least 450 flights had been canceled around the United States as of 7 a.m. ET, with the biggest impacts at Chicago's O’Hare Airport, according to FlightAware, a flight-data tracker.

Sunday was expected to be the biggest travel day of the Thanksgiving holiday weekend at O'Hare International Airport, and the winter storm​ that socked the area this weekend has been more than disruptive.

The National Weather Service upgraded the previous Winter Storm Watch into a Winter Storm Warning, which is set to go into effect for the Chicago area at 3 a.m. Saturday and remain in effect until 6 a.m. Sunday. The warning expires Sunday at midnight for Ford, Iroquois, Illinois and Benton, Jasper and Newton, Indiana.

The blanket of snow covering the Chicago area from Saturday's heavy snowfall will likely be a few inches taller by Sunday evening.

More than 1,100 flights were canceled at Chicago airports as the storm disrupted travel for those headed home after Thanksgiving.

CHICAGO - Residents in Chicago and its suburbs experienced significant snowfall on Saturday. The Chicago area is experiencing the first major snowstorm of the season on Saturday, that is expected to bring multiple inches of snow throughout the afternoon.

Forecasters are anticipating a winter storm to begin late Friday, with snow expected to fall up to an inch per hour into Saturday.

The NWS warned that travelers should consider delaying travel unless it's "absolutely necessary," with driving expected to be very difficult to impossible.