After bitter cold air gripes the Stateline Monday and Tuesday, there will be a moderation in temperatures through the end of the week. The core of the cold air will shift east of Northern Illinois and southern Wisconsin into Tuesday.
Our next system moves on shore today from the Pacific and will push southeast Tuesday morning. The system develops into a low pressure in the southern plains Tuesday morning bringing lighter snow. The system then looks to track east and south of Illinois through the mid south. With this current track in place, northern Illinois and southern Wisconsin looks to accumulate 1-2". However, it will be battling dry air that will be moving in around our high pressure system; that system will be to our north and pushing eastward. Heavier snow stays contained closer to the actual low, with about 2-4" possible. The snow looks to begin late Tuesday night and will last through Wednesday morning, you'll want to allow a little extra time for your commute Wednesday morning.
The low will then strengthen as it lifts northeast and tracks along the East coast. This will be one of the season's first Nor'easters that could bring more accumulating snow along the east coast.