textproduct: Chicago

KEY MESSAGES

- Dry and more seasonable conditions expected through Wednesday before shower and thunderstorm chances return Thursday.

- A corridor of heavy rainfall may occur somewhere in the region Thursday-Friday, though confidence in whether impacts occur locally remains low.

DISCUSSION

Issued at 316 AM CDT Tue Jul 7 2026

A break in the more active weather pattern is in store the next few days with surface high pressure having settled across the region. This should keep shower and thunderstorm chances to our northwest through Wednesday. Temperatures today will be similar to yesterday, perhaps a degree or two warmer, with highs in the low to mid 80s. Light onshore winds paired with a reinforcing lake breeze will keep temperatures cooler (70s) near the lakeshore. The surface high will begin to shift southeast into Wednesday which will bring a return to southwesterly low-level flow and accordingly warmer temperatures (mid-upper 80s) areawide, including near the lakeshore.

Meanwhile the upper level ridge begins to flatten out late Wednesday into Thursday as a pair of low-amplitude waves move across the Upper Midwest. Associated convection across Wisconsin Wednesday evening may attempt to drift toward the state line, though it should be in a decaying state and likely lead to not much more than a few showers into far northern Illinois.

While confidence is high in a period of unsettled weather returning during the Thursday-Friday timeframe, confidence in the details remains low. This is owing to notable model spread in the strength of a separate convectively augmented wave from the Central Plains and whether or not it phases with the aforementioned Upper Midwest wave(s). This will have notable implications as to the degree of impacts that could occur here locally, including the potential for flooding. PWATs will be toward the upper end of climatology and supportive of torrential rainfall rates. A stronger, slow moving disturbance would lead to greater flooding concerns (0Z NAM) and localized severe threat. Whereas a weaker system that is slower to phase with the northern wave(s) would lead to lower rainfall totals and shift the corridor southward (0Z ECMWF). This is an overall lower predictability event given it will be dependent upon how convection unfolds over the next couple of days to our west. Given this uncertainty, the main message is to keep an eye on the forecast.

While a few diurnally driven showers and storms can't be ruled out on Saturday, surface high pressure begins to expand back across the region over the weekend into early next week which should lead to mainly dry conditions into the first part of next week with temperatures in the upper 80s to around 90.

Petr

AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 611 AM CDT Tue Jul 7 2026

No major forecast concerns are expected for this TAF period as high pressure will remain overhead. Winds this morning will be light with speeds around 5 kts and directions generally out of the north-northwest. Though, some wobbling of directions between 350-010 are possible at times this morning at ORD and MDW. By midday (17-18z) a lake breeze will move inland and result in a more definite easterly wind shift at ORD, MDW and GYY; but speeds will remain light around 6-8 kts. Winds will once again become light and variable after sunset before settling into a southwest direction late tonight into Wednesday morning. Speeds are expected to increase Wednesday into the 10-12 kt range with some occasional teen kt gusts possible. Otherwise, expect mostly clear VFR skies to prevail through the TAF period.

Yack

LOT WATCHES/WARNINGS/ADVISORIES

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