The expected storm system for February 20/21 (Friday and Saturday) has been trending further south, and faster/weaker in recent computer guidance. Rather than a deeper storm system with a large area of heavy snow lingering over the region like previously theorized, we'll likely see a weaker storm system develop and quickly move along and north of the Ohio River during the day on Saturday.
Light snow could develop across central Illinois during the late evening and overnight hours on Friday night as an unrelated clipper moves across the region. During the morning on Saturday this new storm system will likely begin to organize across southern Missouri and begin to quickly move northeast. As the system passes to our south, an area of light to moderate snow will likely develop over central Illinois on Saturday morning lingering potentially into the evening. Further south closer to the track of the low, a rain/snow mix with minimal accumulations is likely. South of Interstate 70 in southern Illinois (as well as Kentucky/southern IN), heavy rain and some thunderstorms are possible.
In Champaign-Urbana, I expect accumulations to remain fairly light at this time, at least relative to what I thought we could be looking at as recently as 24 hours ago. 1-2" seems reasonable for total accumulations from the clipper system on Friday night to the second storm quickly moving to our south on Saturday.
As always, further updates will be forthcoming should things begin to change again.