textproduct: Chicago

KEY MESSAGES

- A stagnant, predominantly precipitation free pattern will prevail through at least mid next week, with seasonably warm daytimes inland, and cooler temperatures closer to the lake.

- After swimming conditions improve this evening, hazardous to dangerous conditions may redevelop at Lake Michigan beaches on Saturday.

DISCUSSION

Issued at 150 PM CDT Thu May 28 2026

Persistent western CONUS troughing and northeastern North America troughing will result in a sharp "omega block" type ridge extending into central Canada through midweek next week. Expansive, seasonably strong surface high pressure from Hudson Bay to the Great Lakes will lock in warm regime, though it will be cooler by the lake. In addition, synoptic easterly low level flow will be prone to dew points mixing out daily (and likely running below much of the guidance), keeping better column and low level moisture, and any associated precip chances west of the MS River. This will also result in comfortable overnight- early morning conditions outside of Chicago.

The backdoor frontal passage that brought dangerous swimming conditions to the beaches today and lake cooling extending much farther inland will revert to a classic lake breeze type setup on Friday. Another backdoor frontal passage early Saturday will bring a repeat of similar conditions to those of today. Hazardous to dangerous (moderate to high swim risk) conditions may redevelop at Lake Michigan beaches, which may necessitate a Beach Hazards Statement for at least portions of the shoreline Saturday.

Signs are pointing toward the blocking regime finally breaking down later next week, which may enable some spotty precip chances to return as dew points become a bit more early June-like.

Castro

AVIATION /00Z TAFS THROUGH 06Z SATURDAY/

Issued at 550 PM CDT Thu May 28 2026

There are no aviation concerns through the TAF period.

A surface high pressure system centered over the Upper Peninsula of Michigan will drift southward through the next 24 to 30 hours setting the stage for calm winds overnight and light (5 kt or less) winds tomorrow across the general region. A lake breeze will push inland from Lake Michigan by early afternoon, favoring 18-19Z at GYY, and 19-20Z at ORD/MDW. Broken upper-level clouds based between 30-35kft will continue to stream overhead through tomorrow.

Finally, cannot rule out an isolated patch or two of shallow fog with reduced visibility tonight at outlying airports (RFD/DPA).

Borchardt

LOT WATCHES/WARNINGS/ADVISORIES

IL...Beach Hazards Statement until 8 PM CDT this evening for ILZ006- ILZ103-ILZ104.

IN...Beach Hazards Statement until 8 PM CDT this evening for INZ001- INZ002.

LM...Small Craft Advisory until 7 PM CDT this evening for the IL and IN nearshore waters.