Scattered showers dotted the skies for much of Thursday afternoon, but have now moved to the east Thursday evening. While a few light showers will still be possible through the night, most of the steady rain has ended. The chance for rain will return Friday afternoon, but is expected to increase Friday evening and night. A warm front just a few thousand feet above the surface will lift north into southern Wisconsin after Midnight, pulling in a warmer air mass aloft. This warm air advection aloft is what will support some of those storms going into Saturday morning.
During the afternoon Saturday, the warm front will still remain across central Illinois. Low pressure will lift into central Iowa Saturday afternoon and evening, pulling the front north as it does. Just how far north the front goes will determine our severe storm potential late Saturday afternoon and evening. As of Thursday evening, it looks like the front will lift up near I-88 with a very warm and moisture rich air mass to the south.
Thunderstorms will likely redevelop during the afternoon to the west across western Illinois and race to the east/northeast through the evening. Locally, if storms do develop large hail and damaging winds would be possible, but tornadoes could also occur – especially right along the warm front. The Storm Prediction Center has highlighted the entire Stateline under a marginal risk for storms (green shading), but areas along and south of I-88 under a slight risk (yellow shading). It’s possible that the slight risk could be shifted further north in the days to come. It’s important to remain ‘weather aware’ heading into the weekend. It’s not a guarantee that severe weather will occur Saturday, but the potential is there.