Passengers are seeing hundreds of flight delays and cancellations as a winter storm blasts across the central and eastern United States, while Boeing 737 MAX 9 planes have been grounded. 

Following hours of snowfall and rain overnight, a second wave is expected to hit Chicago on Tuesday, the National Weather Service said. As most of the city is under a winter weather advisory or a winter storm warning, more than 100 flights have been canceled at O’Hare and Midway International airports, according to a site run by the Chicago Department of Aviation.