A strengthening storm system over the southern Plains will push a warm front northward, moving through central Illinois Friday evening. Showers and thunderstorms are likely across the area tonight. As the front lifts through the region, the atmosphere will become more unstable, leading to the possibility of severe weather developing. Current indications suggest that large hail and damaging winds will be the primary severe weather threats. The severe weather risk will mainly be in areas south of I-74, with greater risks back into Missouri and southwest Illinois.
On Saturday, a strong upper-level storm system will push east out of the central Plains. Showers and thunderstorms are expected to develop west of the Mississippi River by afternoon, and push eastward into Illinois. Some of these may be severe, with large hail will be the initial threat, followed by an increasing threat of wind damage. Areas south of I-70 have a greater risk of severe weather, with a widespread outbreak likely from the Ohio Valley southward.
An extended period of wet weather is expected through the weekend, the first such period in a couple of weeks, as the associated upper level storm system slowly moves through the Midwest. Rainfall amounts of 1 to 2 inches will be likely, with some locally higher amounts.