textproduct: Chicago

KEY MESSAGES

- Dry conditions and warmer temperatures are expected through Tuesday.

- Precipitation chances and cooler temperatures return mid to late week.

DISCUSSION

Issued at 116 PM CST Sun Nov 8 2026

Quiet and dry weather conditions will persist through at least Tuesday. Low-amplitude mid-level ridging moving over the area Monday will transition to broader WNW flow aloft by Tuesday. Meanwhile, a surface ridge will cross the area late tonight through Monday morning. With dew points in the low to locally mid 40s this afternoon, the combination of decreasing winds and clear skies tonight supports at least a potential for shallow fog across interior northern Illinois late tonight into Monday morning. As has been observed the past couple days, this may ultimately translate into heavy dew/frost instead of more pronounced fog. Daytime highs will continue to run seasonably warm (generally upper 50s to low 60s) through Tuesday.

A substantial change in the overall weather pattern will lead to a noticeably colder and more active stretch of weather midweek through next weekend. An increasing number of ensemble members are latching onto a compact wave crossing near or over the forecast area on Wednesday. With the associated energy progged to detach from a parent wave currently well west of British Columbia, the exact evolution of the system remains quite uncertain. However, the combination of a contracting low- level baroclinic zone below seasonably strong mid-level rates and within PWATs near or above the 90th percentile for mid- November supports a corridor of modest rainfall and perhaps embedded thunderstorms. While the severe weather potential looks to be quite low, cannot rule out small hail with any elevated discrete cells.

Wednesday's system will congeal into a developing long-wave trough over the Great Lakes region late in the week as unseasonably strong ridging takes hold from the Rockies toward Hudson Bay. This will create a favorable lake effect precip for northeast Illinois into northwest Indiana Thursday and especially Friday into Saturday. Precip type favors rain as ice generation will be an issue with minimum convective cloud tops of only -11C. Additionally, an extensive fetch over the unseasonably warm waters of Lake Michigan suggests near-surface thermal profiles will remain warm enough for primarily rain. With all that said, it seems likely that some snowflakes will mix in with lake effect showers at times.

Kluber

AVIATION /18Z TAFS THROUGH 00Z TUESDAY/

Issued at 1106 AM CST Sun Nov 8 2026

A strong pressure gradient across the Lower Great Lakes will continue to support sustained westerly winds of 10 to 15 kt and occasional gusts up to 25 kt through the afternoon hours. Wind magnitudes will begin to subside after sunset and may become calm as early as midnight as a surface pressure ridge approaches. Winds will slowly become southwesterly and increase to 5-10kt toward the end of the TAF period along the backside of the surface ridge.

Compared to the past few nights, conditions for fog late tonight into tomorrow morning appear better particularly with westward extent closer to the center of the approaching surface ridge. Did introduce a TEMPO group for 1 1/2SM BR at RFD centered on the climatologically favored period for lowest visibility (11-14Z) keeping in mind visibility very may well fall below 1/4SM. Will also have to consider adding for to DPA as well, but will withhold for the time being with an expectation for a wee bit of flow (3-5kt). Should fog develop, it should ease by mid- morning amidst FEW to SCT high- based clouds.

Borchardt

LOT WATCHES/WARNINGS/ADVISORIES

IL...None. IN...None. LM...Small Craft Advisory until 6 PM CST this evening for Winthrop Harbor IL to Burns Harbor IN.

Small Craft Advisory until 3 AM CST Monday for Burns Harbor to Michigan City IN.