Winter is off and running! The pattern of regular cold surges -- punctuated by brief temperature rebounds such as the one in progress as Wednesday dawns -- is to continue beyond mid-month. As if on cue, December's arrival initiated a parade of wintry weather systems across the Chicago area. The second such weather system -- armed with 6 to 8 hours of mixed precipitation and likely to reach the city shortly after midday -- threatens to have some impact on the afternoon and evening rush hour. This is not the huge, moisture-endowed system that hammered the area Sunday and Monday. Computer models late Tuesday were even beginning to suggest its heaviest precipitation is to target Wisconsin more directly than the Chicago area. But the disturbance buried Glacier County, Montana, with up to 9.3 inches of snow Tuesday. Precipitation totals are to be far less dramatic here. In fact, precipitation is likely to begin in an above-freezing environment and is to start as rain or a rain/sleet mix. The air should cool expeditiously with the onset of precipitation, switching to sleet and snow. A final period of snow is to occur as the disturbance exits the area early Wednesday. The best estimate is that 1 to 2 inches of snow may accumulate.
--Tom Skilling, Chief Meteorologist, WGN-TV/Chicago Tribune
