Shirripa says any plows out Thursday were not related to the upcoming storm; drivers were busy running their normal schedules.
Harve, Montana was slammed with 13 inches of snow over a 30-hour period while freezing rain across parts of the state Thursday created hard traveling conditions.
Estimated accumulation in Woodstock exceeded six inches, Romeoville exceeded four inches and St. Charles received 4.5 inches.
Chicago was anticipating eight to 14 inches of snow over the next 24 hours, with the heaviest snowfall on Thursday night and early Friday morning, Gino Izzi, a National Weather Service meteorologist in Romeoville, Illinois, said in a phone interview on Thursday. As of 9:30 a.m., more than 740 flights have been cancelled on Friday at O'Hare, and more than 280 have been cancelled on Friday at Midway.
Winter storm warnings have been issued for most parts of southern Alberta, with up to 50 centimetres of snow expected in some parts of the Rockies. The advisory, according to NWS, "means that periods of snow, sleet or freezing rain will cause travel difficulties".
The latest winter storm is fueled by an impulse of energy flowing through a broad southward dip in the jet stream - lifting moist air over a surface frontal system.
Winter Storm Warning end time moved up to noon CST Friday – snowfall totals still could reach a foot in some areas – more snow on the way Friday night into Saturday
"High will be near 37 degrees, with wind chill values between 15 and 25".
At times, the storm dumped more than 1 inch per hour, the National Weather Service said.
Areas could get more or less snow depending on the track of the storm, so stay aware of the changing forecasts.
Early Friday, the National Weather Service received reports of 4 inches (10 centimetres) of snow in northern IL. We're looking at highs in the upper 20s, but we're also going to keep a close eye on temperatures, especially in Monroe County and Downriver, where it's possible we could see a brief mix of precipitation.
Road conditions began deteriorating Thursday night as the system neared Chicago, the Illinois Department of Transportation tweeted. Slow down when traveling on snow covered roads.