textproduct: Chicago

KEY MESSAGES

- Isolated to scattered showers and storms around and south of US-24 through early this afternoon

- Drier and warmer conditions are expected through early next week; cooler near Lake Michigan.

DISCUSSION

Issued at 128 AM CDT Sat Jul 11 2026

Showers and storms continue to linger in central Illinois south of the forecast area, but most of the activity from Ford County northward has diminished. A 700 mb wave, whose axis is currently analyzed over the area along a Topeka, KS to Detroit, MI line, will continue to sink southward through the morning which will slowly pull the higher moisture content south of the forecast area as well. Weak forcing from a departing wave prevents any real concerns for widespread coverage; however, isolated to scattered showers and storms are still possible through late morning/early afternoon, most likely around and south of US-24. Shower and storm chances decrease late afternoon as the wave finally moves southeast of the area.

Afternoon high temperatures today were lowered by a degree or two from the previous forecast in large part due to the extensive cloud cover over the area. While guidance indicates cloud cover to decreasing through the day as the wave exits, substantial clearing is not expected until early to mid afternoon helping to mute temperatures slightly. Additionally, prevailing northeast winds will help keep cooler temperatures along the lake shoreline.

Warmer and drier conditions will be the trend over the weekend into early next week. An amplifying ridge out west will deepen and tilt northeastward centering the area of high pressure directly over Chicagoland. 850 mb temperatures are forecasted to reach 20C by Monday helping to increase high temperatures back into the 90s. There is a little uncertainty with dew point temperature trends next week, but heat indices are expected to max out around the mid 90s. Additionally, there is the potential for afternoon lake breezes which would help provide some heat relief near the shoreline.

So how long will the heat last? Most models have the ridge maintaining its strength through Tuesday and potentially lingering into Wednesday. After that, models are really struggling with how the ridge breaks down. There is decent consensus of a stout upper level low traversing Canada through next week with the potential of dipping its figurative toes into the northern Great Lakes mid to late next week which would bring cooler temperatures and maybe some showers/storms (depending on its track). However, a few models are suggesting the very same wave currently over Illinois will sink toward the Gulf this weekend, pivot slightly early next week, then slowly work its way northward pulling Gulf moisture with it by mid/late next week. For now, no changes were made to the chance PoPs the NBM provided, but there is a lot yet to be determined with how these system evolve and the potential for cooler air moving in late next week and into the weekend.

DK

AVIATION /12Z TAFS THROUGH 18Z SUNDAY/

Issued at 556 AM CDT Sat Jul 11 2026

There are no significant aviation weather concerns. Light/variable winds will quickly turn northeasterly and increase towards 10-15 kts this morning, and some occasional gustiness towards 20 kts will be possible at times. Winds will ease this evening before returning out of the NE around 5-10 kts through Sunday. VFR will prevail with decreasing high cloud cover through the day.

Carlaw

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...None.