(CBS) – Near white-out conditions and the return of a phenomenon known as “thundersnow” combined to create bleak and treacherous travel conditions Monday, for pedestrians and motorists alike.

Up to 8 inches of snow was expected in some areas of Chicagoland, adding to an already higher-than-normal tally this season.

Instances of “thundersnow” – a thunderstorm that has snow, instead of rain – were documented in Chicago.

National Weather Service Meteorologist Andrew Krein says thundersnow is relatively rare. It requires a strong system that produces a lot of instability.

“We’ve been talking around the office here. The last time we can recall thundersnow in the Chicago area is with the Groundhog Day blizzard a couple of years ago,” he tells WBBM’s Steve Miller.

This time, we’re getting considerably less snow than the 20-plus inches we got in that storm in 2011.

Also Monday, wind and snowfall combined to reduce visibility.

Authorities across the Chicago region reported several weather-related accidents, including a pileup that closed lanes on Interstate 55 at Illinois Route 47, south of Morris on Monday afternoon.

More than 1,000 flights had been canceled at Chicago’s airports, with others delayed because of the weather, the Department of Aviation reported.

Help is on the way, in the form of warmer temperatures, but that will bring a new problem: potential flooding.  The city’s Water Department is asking residents to watch for catch basins clogged by debris and at least call 3-1-1 to report them.