textproduct: Chicago

KEY MESSAGES

- Dry weather with seasonable temperatures are expected through much of the upcoming week.

DISCUSSION

Issued at 1251 PM CDT Sat Oct 3 2026

The sun is shining and a look out the window (and most area webcams) show the sky with a brilliant blue color. Temperatures have climbed into the mid 60s under the sunshine with upper 60s expected for the high temperature today. GOES satellite water vapor imagery shows an amplifying wave over the eastern Dakotas and west-central Minnesota presently. Showers and isolated storms accompany the reflected surface front with the wave and are expected to track east through the overnight. The forecast leaned on the HRRR/RAP solutions (as they are doing a pretty good job at current conditions in the northern Plains) which keeps most, if not all, of the precipitation in Wisconsin tonight. A sliver of slight chance PoPs were kept in the northern tier counties just south of the Wisconsin state line, but given the amount of dry air over Illinois, confidence is higher in just a few sprinkles compared to a wetting rain. Soundings show lapse rates aloft that are not terrible overnight, but instability should weaken as the system crosses the Mississippi River keeping the risk for lightning at bay. The system should mostly pass over harmlessly, switching southeast winds to the northwest behind the front and ushering in a cooler, drier air mass.

Any mid-level cloud cover that moves over northern Illinois tonight with the system should help quell any localized shallow fog chances tomorrow morning. As winds turn to the northwest, temperatures will fall into the low 40s. Given the northerly flow expected tomorrow, high temperatures were nudged down slightly, but with cloud cover decreasing through the day, temperatures should once again return to the upper 60s with areas along and south of I-88 reaching the low 70s. Clearer skies are expected tomorrow night which will help drop temperatures back down to the low 40s with rural areas having a better chance at touching the upper 30s.

Seasonable temperatures will prevail through the week. High pressure will help maintain mostly drier conditions, although another wave over the northern Plains heading to Wisconsin mid-week will be monitored. Guidance continues to favor the track of the system north of Illinois so, for now, no precipitation is in the foreseeable future.

DK

AVIATION /00Z TAFS THROUGH 06Z MONDAY/

Issued at 612 PM CDT Sat Oct 3 2026

Over the next 12 hours, a vigorous upper-level shortwave and associated surface low are expected to move across the Upper Great Lakes. As the system moves through, generally light (10kt or below) south to southeast winds will gradually turn southwesterly through the night. Mid-level isentropic ascent will support bands of mid-level clouds and perhaps a few sprinkles through the night as well.

After daybreak, a cold front will move through the terminals turning winds west northwesterly. Efficient mixing will afford occasional gusts of 15 to 20 kt during daylight hours. Wind magnitudes will subside quickly after sunset as decoupling commences and the center of a surface high pressure system approaches from the west. Winds at ORD/MDW may trend westerly by the end of the 30-hour TAF window owing to the development of a land breeze, but will keep a mention out for now given limited expected impact to aviation services.

Borchardt

LOT WATCHES/WARNINGS/ADVISORIES

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