Low pressure currently developing in Colorado will track E/NE into the Great Lakes by Saturday evening. This system is quite different than those we’ve recently seen, as it is approaching from the southwest and has more moisture and warmer air to work with. As a result, a wide variety of wintery precipitation is expected across central Illinois.
Light snow will develop by around midday on Friday, January 31st then continue into the early evening hours. This initial surge of precipitation will be quite light, with most locations along/north of a Jacksonville to Danville line measuring less than 1” of snow. Further south, conditions will be warm enough to support all rain or a rain/snow mix south of I-70.
As low pressure ejects northeastward out of Colorado, precipitation will become heavier from late Friday evening through early Saturday afternoon. Warmer air lifting northward ahead of the system will allow the precipitation to change to freezing rain or just plain rain across a large swath of central and southeast Illinois…with mainly snow falling from the Peoria area northwestward.