Active AlertsSouthern Cook

What: For the Winter Weather Advisory, a period of snow is expected, possibly heavy at times. A quick 1 to 3 inches of accumulation is expected within a few hour period. For the Winter Storm Watch, heavy lake effect snow possible. Snow accumulations of 6 or more inches are possible, mainly east of the Dan Ryan and I-57.
Where: Central Cook and Southern Cook Counties.
When: For the Winter Weather Advisory, from 9 AM to 3 PM CST Friday. For the Winter Storm Watch, from Friday afternoon through Friday evening.
Impacts: Travel will likely become hazardous as roads become snow covered during the mid to late morning through early to mid afternoon Friday. If heavy lake effect snow affects eastern Cook County late Friday afternoon and Friday evening, travel within the affected areas could be severely disrupted.
Additional Details: A burst of accumulating snow is expected mid to late Friday morning through early afternoon. The snow during this period may briefly fall at a rate of up to an inch per hour and make for hazardous travel conditions. Then, later Friday afternoon and evening, an intense band of heavy lake effect snow will develop over southern Lake Michigan, and may impact eastern portions of central and southern Cook County late Friday afternoon or evening. While the residence time of this lake effect band over Cook county may only be 3 to 5 hours, it would likely produce very heavy snow rates of 2 or more inches per hour and could result in localized accumulations exceeding 6 inches. Confidence is still low in whether eastern Cook County will be impacted by the lake effect band Friday afternoon and evening, if the band stays east over the lake into Indiana, then very little additional snow may occur.

During lake effect snow, the weather can vary from near white out conditions in very heavy snow to dry weather just a few miles away. Be prepared for rapid changes in weather, visibility, and road conditions. Monitor the latest forecasts for updates on this situation.