textproduct: Chicago

KEY MESSAGES

- Pockets of light rain early this morning may continue as sprinkles into this afternoon.

- Generally dry conditions are expected this week. Beyond this morning, our next chances for rain don't arrive until Friday.

DISCUSSION

Issued at 239 AM CDT Mon Jun 1 2026

Early this morning, we find some rain pushing across the CWA north of I-80. While the rain has largely been on the lighter side, embedded pockets of moderate rain have been observed. Some sites have even been recording 4 to 5 mile visibilities beneath some of the heavier showers. This rain is the result of a shortwave upper impulse scooting overhead. Model guidance was correct on the low level dry air tonight with ceilings between 6 and 8 kft with these showers and 10 to 15 degree surface dewpoint spreads. However, most severely undermined the strength of this wave and the resultant modest frontogenetic forcing that are now allowing for this more moderate rainfall.

These showers are anticipated to continue working eastward toward and out over the lake through early morning. The shortwave will break down and get sheared out across the area this morning into the afternoon. The loss of forcing and low level dry advection after daybreak should phase out the true shower development through the morning. However, as the wave and associated vorticity sloshes back across the CWA during the day, wouldn't be surprised to see additional sprinkles around the area into the afternoon. In the forecast, got rid of true shower mention after early morning but maintained a slight chance for sprinkles later into the day.

Skies will be mostly cloudy through the daytime before thinning out and similar temps to yesterday are expected this afternoon with highs progged in the middle and upper 70s to lower 80s in our south and southwest CWA. A northeasterly breeze will again bring cooler conditions to locales near the lake today.

The remnants of last week's blocking upper high will drop south into the region from Canada tomorrow and park surface high pressure around the Great Lakes and Midwest through the middle of the week, meaning rain chances are basically zilch in the Tuesday through Thursday window. Middle 70s to lower 80s are again forecast for tomorrow afternoon. By Wednesday, the high will push far enough east of us to bring some mild return flow to the area and highs are forecast in the lower and middle 80s inland of the lakeshore. Between the high to our east and a developing storm system over the Plains, we'll find ourselves locked in a southerly flow regime for late week and a high theta-e air mass will overspread the region with highs favored in the middle to upper 80s and dewpoints climbing back into the 60s. By Friday, that synoptic system will translate east into the Midwest and bring a good shot at seeing some showers and possibly thunderstorms, especially later Friday. Medium range guidance then flips the switch on us and suggests a rather active synoptic pattern with frequent opportunities for rain could be in store for this weekend and early next week.

Doom

AVIATION /12Z TAFS THROUGH 18Z TUESDAY/

Issued at 556 AM CDT Mon Jun 1 2026

An area of showers will continue to shift east of the Chicago- area terminals this morning with lingering BKN-OVC cigs near 6-7 kft. A secondary disturbance will move across the region later this morning/midday which could result in the development of additional sprinkles/light showers. Chances appear fairly low, and any potential impacts would be brief/minor. Have refrained from additional precip mentions in the outgoing 12z TAFs as a result.

Northeasterly winds will increase a bit this morning to around 10 kts and may receive a brief boost as well this afternoon behind a lake breeze/weak backdoor front. Winds will ease a bit overnight before increasing again out of the ENE/E on Tuesday. VFR conditions are expected.

Carlaw

LOT WATCHES/WARNINGS/ADVISORIES

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