DENVER (AP) — A storm that has dumped more than a foot of snow in the Rocky Mountains could cause headaches for travelers in the Midwest. Drivers in Iowa and Nebraska are being warned to be careful or stop driving altogether starting Wednesday evening as the first major winter storm of the season heads into the central Plains. Strong winds are expected to create blizzard conditions.

Light snow is also expected at Chicago’s O’Hare International Airport on Thursday and strong winds could make visibility poor. National Weather Service forecaster Jamie Enderlen says that, combined with low clouds, could cause delays at the nation’s second-busiest airport. Delays at Denver’s airport, the fifth-busiest, were averaging 30 minutes because of snow and ice Wednesday. Interstates in Colorado remained open.