Winter Storm Watches have been issued for all of southern Wisconsin and northern Illinois ahead of what could be this winter’s biggest snowfall yet. Two low pressure systems will work together spreading rain across much of southern and central Illinois Monday afternoon and evening, before lifting into northern Illinois Monday night.
Skies will remain mostly clear through Sunday evening after temperatures warmed into the low to mid 50s during the afternoon! Cloud cover will increase during the overnight leaving skies mostly cloudy by Monday morning. Dry air overhead during the day Monday will keep us mostly dry, but as moisture increases from the south during the evening and overnight light rain showers will be possible across parts of Whiteside, Lee and DeKalb counties. Cooler air will settle in from the north as northeast winds increase by Tuesday morning. This will allow rain showers to mix with, and eventually changeover to, snow during the morning and continue into the afternoon and evening.
The snow Tuesday could be heavy at times, especially through the evening, likely having an impact on the commute Tuesday. Those impacts could last into Wednesday morning. Northeast winds will also increase throughout the day Tuesday with blowing and drifting snow possible heading into Tuesday evening. The overall track of the low will determine where the heaviest falls, but as of Sunday evening that potential looks to fall very close to, if not over, northern Illinois and parts of southern Wisconsin. Within the heaviest snow, totals could approach six inches or more. Strong lift in the atmosphere tied to the upper level low may even be enough to push snow totals into the double digits when all said and done, but that would be over a very localized area. Right now, it looks like most should receive between 5-9 inches of snow.
It’s important to note that there was a slight shift south in a couple of the forecast models Sunday, placing the heaviest snowfall just to the south of the immediate area. Should the southern track hold the highest snow totals would likely fall along and south of the I-88 corridor Tuesday into Wednesday. However, if the low moves through central Illinois then the heaviest snow would come down across northern Illinois and south-central Wisconsin.
In some places Tuesday morning there may be an inch of snow on the ground, but the morning commute shouldn’t be too impacted. If the current forecast hold, conditions would deteriorate during the day Tuesday into Tuesday evening, likely lasting through Wednesday morning.