Late week system may bring significant snow to Chicago area

by: Paul Merzlock, WGN-TV Weather Team

Posted: Dec 19, 2022 / 12:29 AM CST

Updated: Dec 19, 2022 / 12:30 AM CST

After 9 days under cloud cover, skies cleared across the Mississippi Valley region revealing the extent of snow cover left from last week’s storm. 

Probability of significant snowfall later this week continues to rise

What these numbers mean:  At this point (4 days ahead of this possible event), these probabilities for a significant (4+-inch) snowfall are actually fairly high. The first contour – probabilities >30% mean the forecast snow amount is likely. Probabilities >40% suggest the occurrence is very likely. Keep in mind that 2 days ago these probabilities were under 20%.

Forecast models coming into agreement on late-week storm track

Inconsistencies remain, but general consensus takes deepening storm center east of Chicago late Thursday into Friday suggesting significant snowfall across Chicago

Snowfall forecast totals

Though the National Weather Service’s GFS model is more aggressive on forecast amounts from this potential snowstorm, the consensus among various models is that Chicago may be in line for a significant late-week snowfall.  

Timing of potential snowfall

Models are in reasonable agreement on when snow may fall later this week. The GFS model is more generous with the amounts, but the timing shown here is consistent with other forecast guidance. Occasional snow may begin around daybreak Thursday, but greatest accumulation rates are currently forecast to occur Thursday night into Friday.