CHICAGO -- Chicago Public Schools has canceled Friday classes as a winter storm moves across the Midwest that is forecast to bring between 8 and 14 inches of snow to northern Illinois.

Chicago school officials on Thursday joined others around the state expecting a difficult commute for students and teachers on Friday.

The National Weather Service has winter storm warnings in effect for the northern swath of Illinois from 6 p.m. Thursday through Friday evening. The heaviest snow totals are expected north of Interstate 80 to the Wisconsin state line. Snowfall is forecast to be heavy at times with rates of 1 to 2 inches per hour possible.

Snow is to start during the Thursday evening commute but the most significant impacts are expected for the Friday morning commute.

The weather service's warning says "travel will be difficult to impossible at times."