i don't know about illinois, but in the tx panhandle we get a lot of the same weather yall do. we catch cats all through the winter, even through holes in the ice. smaller bait seems to be the key. the channels here have been in a feeding frenzy since february. crushed fathead minnows have been the ticket since then. as the water warms, the baits get bigger, and we switch over to live perch, cut perch, and whole large shad. the best way to find when fish turn on in your area is to get out there and fish em hard! you'll get their patterns figured out pretty quick, and they follow a similar pattern year after year, with a few variables, like spring cold snaps and high water due to rain. hope this helps ya out bud!