Low pressure will move out of the Plains Friday and into Missouri and then southern Illinois by Saturday morning. As it does a mixture of snow, sleet and freezing rain will be possible during the overnight Friday into early Saturday.
The majority of the day Friday will be dry but clouds will be on the increase through the afternoon and evening. A fairly dry air mass coming down from Canada will keep most of the precipitation to the southwest of the Stateline until roughly 9pm-11pm Friday night. As the air mass begins to cool near the surface, a shallow layer of warm air will be present roughly 5,000ft above the surface. This warm layer of air will work to melt any frozen precipitation as it falls from the clouds Friday night.
Temperatures near the surface will be close to freezing, if not below, during the overnight bringing a chance for sleet and freezing rain at times. Minor accumulations of both snow/sleet and freezing rain are possible, especially on elevated surfaces.
Slick spots are likely Saturday morning but may only be confined to elevated surfaces as warm pavement temperatures could limit ice or snow accumulations on the road. One limiting factor to just how much precipitation could fall will be the amount of dry air in place ahead of the incoming low. East/northeast winds will remain fairly persistent through much of Friday, keeping a dry air mass in place over much of southern Wisconsin and northern Illinois. If the dry air is able to overcome any moisture lifting north, then the majority of the precipitation that occurs will be rather light. However if the moisture is able to overcome the dry air quickly Friday night, then minor accumulations of snow and sleet are likely by Saturday morning.
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