Conditions outside will be changing fairly quickly from Sunday night to Monday morning. A strong low pressure system will lift northeast from the southern Plains into the Great Lakes by Tuesday morning.
Sunday evening a mixture of rain, sleet and freezing rain has been occurring over northern Missouri, Iowa, Nebraska, Kansas and central Illinois. All of this precipitation will remain south of the Stateline through Midnight, and likely through 2am or 3am Monday. Surface temperatures over northern Illinois and southern Wisconsin have fallen into the upper 20's and low 30's and are not expected to rise back above freezing until Monday afternoon.
As moisture is pulled north it will encounter the colder air at the surface. This will lead to a period of sleet and freezing rain from very early Monday morning through roughly Noon. Minor ice accumulations are likely with some locations receiving up to 0.10". This isn't enough to bring down power lines or cause power outages, but it is enough to cause issues on the roads.