textproduct: Chicago

KEY MESSAGES

- Dangerous swimming conditions due to large waves and strong currents expected through Wednesday morning.

- Rain chances return by late Friday into Saturday.

DISCUSSION

Issued at 148 AM CDT Tue Jul 28 2026

Winds will becoming north by sunrise in the wake of a cold front moving across the area early this morning. Cooler and much less humid air will filter into the region in the wake of this front. Visible satellite imagery from Monday afternoon showed smoke upstream, which the HRRR smoke model brings into our area today. Have adjusted sky cover up some to account for this once the lower clouds this morning clear out. HRRR smoke model keeps near surface smoke concentrations fairly low, and there aren't any meaningful visibility restrictions upstream, so not expecting a repeat of the dense smoke from a couple of weeks ago.

Gusty northerly winds down the full fetch of the lake will result in large waves and dangerous currents through tonight and likely into Wednesday morning. A beach hazard statement remains in effect for this time period.

Dry and seasonable conditions are expected until the next system arrives late in the week. GFS and ECMWF both amplify a shortwave as it approaches the Midwest Friday. GEFS and EPS both support this system evolving into a closed mid-upper level low in the mid-Mississippi Valley Friday night into Saturday. Once the system closes off, guidance slows it down and its progged to meander around the region this weekend. While there is good agreement between the GEFS and EPS means, it is worth noting that medium range guidance often struggles with handling closing off systems like this, particularly in the summer when synoptic pattern can frequently be significantly altered by convective processes. Having said all of that, the NBM pops for this period look quite reasonable, with low end likely pops Friday night into Saturday. While nothing off the charts, PWATs look to be seasonably high, so given the potential for a slow moving cut off low, there could be a heavy rainfall threat developing somewhere in the Midwest this weekend.

NBM is dry Sunday into early next week, but depending on where that mid-upper level low meanders, it wouldn't be hard to envision a scenario where rain chances need to be added to the forecast for Sunday and even into Monday.

- Izzi

AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 641 AM CDT Tue Jul 28 2026

Main Concern:

- Low CIGs through midday today, with 1-4SM BR near the lake

MVFR to IFR CIGs are currently overhead, along with MVFR to IFR VSBY in fog/BR near Lake Michigan (lowest VSBY closer to the lakeshore) through mid to late morning. Once the clouds scatter by midday/early afternoon (likely taking longest to improve at MDW and GYY), expect VFR conditions the rest of the period.

North-northeasterly winds will gust up to 20-25 kt near the lake until diminishing this evening. There will probably be a land breeze associated shift to a north-northwesterly direction tonight at ORD and MDW, returning to northeasterly by mid Wednesday morning.

Castro

LOT WATCHES/WARNINGS/ADVISORIES

IL...Beach Hazards Statement through Wednesday morning for ILZ006- ILZ103-ILZ104.

IN...Beach Hazards Statement through Wednesday morning for INZ001- INZ002.

LM...Small Craft Advisory until 7 AM CDT Wednesday for the IL and IN nearshore waters.