textproduct: Chicago

KEY MESSAGES

- Moderate swim risk at southern Lake Michigan beaches through tonight due to persistent breezy onshore winds and increased rip current threat.

- Drier and more seasonable conditions expected through Wednesday before shower and thunderstorm chances return late week.

DISCUSSION

Issued at 237 AM CDT Mon Jul 6 2026

A mid-level ridge axis is in the process of building into the upper Midwest and western Great Lakes this morning and this will bring us some tranquil weather to start the week. However, the 700 mb low that brought us the scattered showers yesterday has not made as much eastward progress as guidance suggested 24-hours ago. In fact, nighttime microphysics imagery shows this low sitting over southeast lower MI and northern OH. Attached to this low is a modest baroclinic zone stretching from the low southwestward into eastern MO and this axis looks to be the spot for isolated to widely scattered showers and thunderstorms to develop today. Given that the baroclinic zone is south of our area, the expectation is for most of northeast IL and northwest IN to remain dry but a stray shower (maybe with an associated lightning strike) cannot be ruled out near and south of a Paxton, IL to Rensselaer, IN line.

Aside from the non-zero rain chance, today will feature partly to mostly sunny skies with temperatures once again in the low to mid-80s inland with mid to upper 70s expected near the lake. Persistent northeast winds will become breezy this afternoon (localized gusts around 20 mph) which will maintain 2 to 4 feet waves at area beaches through tonight. Waves of this magnitude will continue to lead to an increased rip current risk especially at unprotected beaches. So if planning to head to the beach make sure bring the life jacket and if conditions are too hazardous for your comfort stay out of the water.

Dry weather will continue into Tuesday as the aforementioned ridge remains solidly overhead. While winds will be notably lighter (speeds around 5-10 mph) they will still be out of the east-northeast which will continue to support locally cooler temperatures near the immediate lakeshore (in the mid to upper 70s). Elsewhere temperatures will be warmer in the mid-80s.

Heading into Wednesday, the mid-level ridging will begin to weaken as a shortwave trough traverses across the northern Plains and into the Upper Midwest. At the same time, the closed low (that is forecast to form from the subtle shortwave diving across MO currently) will begin to lift northward from southern MO towards the Ohio River Valley. Recent guidance trends are showing that northern stream shortwave may arrive later and thus keep the rain potential at bay until either late Wednesday night or Thursday. In fact, forecast soundings do show some decent capping in place across northern IL and northwest IN on Wednesday which should further limit any shower or storm development. So the current forecast will feature dry conditions for Wednesday with temperatures a tad warmer then Tuesday with highs in the mid to upper 80s areawide (including near the lakeshore).

Shower and thunderstorm chances will be on the increase for Thursday as the aforementioned northern shortwave and closed low begin to phase over the southern Great Lakes and push a frontal zone into northern IL and northwest IN. These features should result in widespread showers and thunderstorms through Thursday night, but the modest wind shear looks to keep any severe threat low at this time. However, the presence of a slow moving boundary and relatively weak shear/mid-level flow may set up the potential for slow moving/training showers and storms which could result in periods of heavy rainfall and perhaps even some localized flooding. Right now confidence is low on if training will occur and if it does where the heaviest rain will materialize but this is a period that will be monitored closely over the coming days.

Additional periods of showers and thunderstorms are expected Friday and into the weekend as shortwaves continue to pass through northern IL and northwest IN. Though, coverage and intensity of showers/storms Friday onward is more uncertain as guidance varies on where the waves will track and how previous rounds of convection could alter the environment. Bottom line it looks like another active period with some dry hours mixed in at times. Regardless, temperatures through the extended period (Thursday onward) are forecast to remain seasonable with highs in the 80s and overnight lows in the 60s to around 70.

Yack

AVIATION /06Z TAFS THROUGH 12Z TUESDAY/

Issued at 1233 AM CDT Mon Jul 6 2026

Key aviation forecast messages:

- IFR CIGs ongoing at GYY (may try to expand toward MDW)

An area of IFR to low-end MVFR stratus has developed over GYY early this morning. Have held off on a formal mention at MDW but will monitor trends closely over the next few hours in case it expands farther northwest. SCT to briefly BKN MVFR CIGs can't be ruled out at times prior to daybreak at any of the Chicago area terminals but expect mainly VFR conditions to prevail.

Winds remain light out of the NNE around 5-10 kt across the Chicago metro with variable winds < 5 kt at RFD. Expect winds to increase out of the northeast after daybreak today to around 10-15 kt. Winds then ease and become light and variable after sunset (potentially leaning NNW at ORD/MDW < 5 kt.

Petr

LOT WATCHES/WARNINGS/ADVISORIES

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