textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Chances for thunderstorms tonight through Wednesday evening. A Marginal Risk for severe thunderstorms develops Wednesday afternoon and early evening, with the main hazards damaging winds and hail.

- On and off thunderstorms possible this weekend into the middle of next week.

- Slightly below normal temps continue through Friday with a strong warming trend early next week, potentially nearing Heat Advisory criteria next Monday and Tuesday.

UPDATE

Issued 648 PM CDT Tue Jun 23 2026

An easterly lake breeze has progressed inland to Fond du Lac/Jefferson/Whitewater, and will likely stall within the hour. A decaying MCS will progress southeastward late tonight and produce generally light to moderate rain and isolated lightning across areas north of I-94 (60-80% PoPs). The south side of the system may produce scattered storms across areas south of I-94 late tonight, but expected to be more scattered (20-40% coverage). Precipitation will continue into Wednesday, with a potential break around midday.

MH

SHORT TERM

Issued 1259 PM CDT Tue Jun 23 2026

This afternoon through Wednesday night:

Latest short term models are showing a few sprinkles possible in the east this afternoon, largely due to low level convergence from prevailing light southerly winds away from the lake and easterly winds near the lake. Models soundings are fairly dry though, so will maintain a dry forecast for now.

Moisture and warm air advection are anticipated this evening into tonight along with gradually increasing instability. Precipitable water values around 0.75" this morning are expected to increase to around 1.30" tonight. Forcing and moisture should be plenty for a round of showers and isolated to scattered thunderstorms as a weak wave moves through late this evening into Wednesday morning. Latest models suggest this slow moving wave should bring precip to all of southern Wisconsin, so will maintain the high rain chances. Marginal shear, instability, and lapse rates suggest any storms should stay sub- severe for this first round of precip through Wednesday morning.

A weak surface low and associated front are expected to move through later Wednesday afternoon into the evening. Given enough of a break after the first round of precip, scattered storms may fire as the low and front move through. 0-6 km bulk shear will be in the 30-40 kt range, with surface based CAPE around 1500 J/kg if sufficient recovery occurs. Some organized storm development will thus be possible, with a few strong to severe storms not out of the question. Hail and damaging winds still look like the main concern for any storms that do become severe. The main window of opportunity for stronger storms tomorrow currently looks like 4 to 10 pm. A few showers with isolated thunder may hang on late evening into early night as the main trough swings through, with dry weather then likely the remainder of the night behind the trough.

DDV

LONG TERM

Issued 1259 PM CDT Tue Jun 23 2026

Thursday through Tuesday:

A few showers will be possible in the east tomorrow along surface convergence due to the lake breeze and as weak cyclonic flow aloft lingers. Not out of the question for a rumble of thunder as well. Otherwise, skies should be partly cloudy with highs in the 70s once again.

The upper level flow is expected to be zonal on Friday, with upper level ridging beginning to build in from the west on Saturday. Dry weather is expected both days under surface high pressure. Temps will remain a bit below normal Friday, warming back to around normal Saturday as the upper ridge builds in.

Upper level ridging will continue to strengthen across the Midwest and Northeast United States early next week, with increasing temperatures likely for southern Wisconsin. Dewpoints will increase as well, with a chance for Heat Advisory conditions Monday and Tuesday, especially if it remains dry through this period. That said, there is a chance that storms could move through the top of the ridge and impact southern Wisconsin once or twice from Sat night through early next week. Confidence is on the lower end in any potential precip timing at this point.

DDV

AVIATION

Issued 648 PM CDT Tue Jun 23 2026

Easterly lake breeze all the way east to FLD/UES/BUU will weaken within the next few hours, with light and variable winds expected for the first half of the overnight hours. Winds shift to become southerly by Wednesday morning, then southwesterly gusting 15-20 kt Wednesday afternoon. Winds diminish Wednesday evening into Wednesday night.

VFR conditions expected through late tonight, with MVFR ceilings and visibilities moving in along with steady rain and embedded lightning late tonight into Wednesday morning. Expecting storms to become scattered south of the I-94 corridor during the morning hours, with precipitation ending northwest to southeast midday. During the afternoon and evening hours, expecting an additional round of thunderstorms to progress northwest to southeast, also with local visibility and ceiling drops to MVFR. These storms may become capable of producing damaging winds and isolated large hail. Storms gradually taper off from west to east during the late overnight hours, with conditions improving thereafter.

MH

MARINE

Issued 1259 PM CDT Tue Jun 23 2026

High pressure around 30.2 inches over the Upper Midwest will bring continued light and variable winds throughout the rest of today and tonight. Low pressure 29.9 inches developing over the northern Plains tonight and progressing into northern Wisconsin on Wednesday will bring southwesterly winds and thunderstorms to the lake. Winds shift northwesterly as low pressure exits into Lower Michigan on Thursday, with isolated thunderstorms remaining possible. Light northerly winds expected Thursday night, continuing through Friday. Friday night into Saturday, expect light and variable winds under high pressure around 30.1 inches, before winds shift to become southeasterly Sunday ahead of developing strong low pressure in the northern Plains.

DDV

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...None.