A Winter Weather Advisory will go into effect for Stephenson, Jo Daviess and Carroll counties beginning at 9am Thursday, lasting through 6pm Thursday. The potential for a wintry mix of freezing rain and snow will be slightly higher for folks across northwest Illinois and southwest Wisconsin, while heavier snow will occur further northwest.
Skies are expected to remain mostly cloudy Wednesday evening as winds gradually shift around to the south and southeast. The combination of cloud cover and a southerly breeze will hold temperatures in the mid and upper 20s during the overnight. As a rather strong area of low pressure moves down from the northern Rockies Thursday, a cold front will advance east during the morning and afternoon. Ahead of the front there will be a slight increase in moisture across northern Illinois as temperatures slowly climb to freezing, 32 degrees. Areas west of a line from Monroe to Freeport, down to Forreston hold a slightly higher chance for temperatures remaining right around freezing during the morning, while further east temperatures briefly warm into the mid 30s.
A mixture of snow and freezing rain, at times mixed in with the rain showers, will be highest across northwest Illinois as the cold front crosses over the Mississippi River Thursday morning. This combination of snow and freezing rain could cause some impacts for the mid-morning commute west of Rockford.
By the afternoon the cold front will have passed with colder air wrapping in from the west. This will allow for a rain/snow mix to develop before a transition over to snow occurs after Noon Thursday, with snow showers lasting through the evening. There may be a brief window where the snow is a little more moderate once the changeover begins, with lighter snow expected through the evening.
As low pressure sinks further into southern Wisconsin overnight Thursday the snow showers will become lighter, lasting through Friday morning. Snow totals will range from one to three inches, depending on how quickly the changeover occurs. A later changeover means snow totals will be less. A quicker changeover means snow totals could be closer to two or three inches. Impacts to the early morning commute may be minimal Thursday, but expect some impacts for the afternoon and evening with reduced visibility and slushy roads.