textproduct: Chicago

KEY MESSAGES

- Above average temperatures expected to continue through the upcoming weekend, though tomorrow looks like the warmest day of the bunch.

- While not a wash out, there will be some periodic chances for showers and perhaps isolated thunderstorms at times late Wednesday night through the upcoming weekend.

DISCUSSION

Issued at 1243 PM CDT Tue Oct 27 2026

The rest of the afternoon looks fairly quiet and cloudy as a moisture-starved upper-level waves (currently lifting across the IA/MO border) traverses into the Lower Great Lakes. Suppose a sprinkle or two cannot be ruled out (roughly a 10% chance for rain at any given location).

Wednesday is shaping up to be unseasonably mild area-wide. High temperatures are forecasted to reach the low to mid-70s during the afternoon amidst breezy southwest winds (gusts up to 25 mph, especially with northwestward extent).

The next notable shortwave impulse is expected to track well north across southern Canada Wednesday night. As an associated surface low moves eastward across Ontario, a southwestward- trailing cold front will push southward into our area by Thursday. Although the strongest large-scale forcing will pass well to the north, pooling low-level moisture (dew points in the mid to upper 50s) along the frontal boundary could support isolated to widely scattered showers, particularly late Wednesday night into Thursday. Consequently, we maintain low- end (20 to 40%) chances of precipitation during this period.

Temperatures Thursday and Friday look to be stunted by extensive cloud cover and onshore winds. Have aggressively undercut NBM guidance to now feature highs generally in the mid 60s to around 70 on Thursday to solidly in the 60s on Friday (more more in line with ensemble guidance). Some deterministic guidance suggests highs may struggle to climb out of the 50s on Friday near the Wisconsin state line and Lake Michigan shoreline.

Ensemble guidance suggests a series of impulses will track from Mexico east-northeastward into the Lower Great Lakes region during the weekend, followed by a potentially more substantial system tracking slowly across the central U.S. next week. As a result, there will be daily chances for rain from Saturday into next week. Dry periods are still expected, so it will not be raining continuously throughout the weekend.

KJB/Borchardt

AVIATION /18Z TAFS THROUGH 00Z THURSDAY/

Issued at 1226 PM CDT Tue Oct 27 2026

No significant weather impacts are expected through the TAF window.

VFR conditions are expected to prevail. There remain a couple models suggesting an isolated light shower/sprinkle this evening associated with an upper level wave lifting out of Missouri, but confidence is low. With little impact to operations, it was kept out of the TAF. Winds will continue to be out of the southeast and around 10 knots through this afternoon before gradually diminishing this evening and slowly become southwest. Better mixing tomorrow afternoon may result in breezier wind gusts of 15 to 20 mph. There is some uncertainty in how persistent these gusts will be versus for sporadic in nature. Therefore, only added gusts to 20 knots in the KRFD TAF where there was higher confidence.

DK

LOT WATCHES/WARNINGS/ADVISORIES

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