textproduct: Chicago

KEY MESSAGES

- Next significant chance of rain is Sunday with potential for locally heavy rainfall.

DISCUSSION

Issued at 121 AM CDT Thu Jun 18 2026

After a couple of active days, a much quieter weather pattern expected the next few days. Northwest flow aloft will persist with high pressure across the Ohio Valley blocking any return moisture from the Gulf. A couple of subtle/weak perturbations in the northwest flow will could bring some spotty showers to the area, mainly Friday night. Coverage is expected to be on the low side, as is confidence in it raining, so the slight chance to chance pops offered up by the NBM seem reasonable. Temperatures the next couple of days will be a bit below average with comfortable dewpoints generally in the 50s.

For days now, medium range guidance has been in good agreement in bringing a stronger shortwave trough into the Midwest late in the weekend. By Saturday, the aforementioned surface ridge is expected to shift eastward allowing for southerly flow from the Gulf to advect moisture northward in advance of the next system. There remains some latitudinal variability and differences in guidance with respect to the track of the associated sfc low, but there has been a pretty consistent signal for a swath of potentially heavy rainfall setting up in or near our CWA Sunday. Accordingly, NBM pops are quite high and no changes were needed.

Northwest flow aloft will continue into next week. Drier weather is expected to start the week in the wake of the Sunday system. Next chance of showers/storms looks to be toward the middle of next week. Temperatures next week look to remain near to slightly below average.

- Izzi

AVIATION /06Z TAFS THROUGH 12Z FRIDAY/

Issued at 1228 AM CDT Thu Jun 18 2026

Forecast concerns include...

Mvfr cigs overnight through mid morning. Gusty westerly winds through late this morning.

A large area of mvfr cigs across southeast MN and much of WI is expected to move southeast across the terminals in the predawn hours and persist through mid/late morning. Have maintained cigs around 2kft but its possible there will be a few hours of low mvfr cigs and adjustments may be needed with the 09z update. Once this mvfr cloud cover shifts southeast of the terminals by midday, vfr is expected for the rest of the period.

Westerly winds will gust into the mid 20kt range through mid morning and will then steadily diminish with gusts ending by early afternoon and speeds diminishing under 10kt with sunset this evening. cms

LOT WATCHES/WARNINGS/ADVISORIES

IL...Beach Hazards Statement until 4 AM CDT early this morning for ILZ006-ILZ103-ILZ104.

IN...Beach Hazards Statement through this afternoon for INZ002.

LM...Small Craft Advisory until 9 AM CDT this morning for the IL and IN nearshore waters.