Friday finally brings a drier forecast, unfortunately that won't be the case this weekend.
A trough and wave of energy in the jet stream will eject out of the Rockies today and move closer to the Stateline. Ahead of this, our flow in the upper levels of the atmosphere will be southerly and will strengthen. This brings a ton of moisture into the Stateline, as dew points surge back into the 70's.
High pressure will keep northern Illinois fairly dry through the evening, but it continues it's northeast movement tonight out of the area. A strengthening low level jet will veer from southern Iowa today overhead early tomorrow, which will allow the rain and storms from Iowa to also veer eastward. You'll want to keep an eye on the radar if you have outdoor plans, as we look to see periods of rain and even a few storms through Saturday. Temperatures only warm to 80° but it will be increasing humid. Along with increasing dew points the upper levels of the atmosphere will receive more moisture, this will once again bring the threat for heavy rain at times. There could also be a few stronger storms but threat for that is fairly low because thick cloud cover will limit instability.
The rain threat will slowly decrease into Saturday evening with small rain chances into next week.