CHICAGO (AP) -- A winter storm moving across the Great Lakes that's forecast to drop about a foot of snow in some areas has closed schools and forced the cancellation of hundreds of flights.
The National Weather Service issued winter-weather warnings and advisories across the upper Midwest. The snow that began falling late Thursday afternoon is expected to continue through Friday as the storm moves east.
American, United and Southwest airlines warned travelers to expect more flight cancellations to and from Minnesota, Michigan, Wisconsin, Illinois, Indiana and Ohio.
The expectation of up to 12 inches around Chicago prompted officials to close the city's public schools to about 390,000 students on Friday.
Weather service meteorologist Trent Frey says the forecast is for up to nine inches of snow in Detroit through late Friday. Schools across Michigan also cancelled classes.