textproduct: Milwaukee/Sullivan

KEY MESSAGES

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

- On and off thunderstorms possible this weekend into early 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 650 AM CDT Tue Jun 23 2026

No major changes to the going forecast from the 06z model guidance. Dry and quiet weather expected through at least 9:00 PM CDT this evening. Shower and thunderstorm chances then begin to slowly push from west to east into the region, with the better chances (over 50%) holding off until after midnight tonight.

Sheppard

SHORT TERM

Issued 124 AM CDT Tue Jun 23 2026

Today through Wednesday night:

A few areas of patchy fog in river valleys this morning under clear skies and low to calm winds. Any remaining fog will burn off shortly after sunrise. Winds are expected to remain light and variable throughout today, with an easterly lake breeze developing during the afternoon hours and progressing inland through much of southern Wisconsin through the evening. Expect highs in the upper 70s inland, with highs in the low 70s to upper 60s near Lake Michigan and immediately inland. Cloud cover will increase through the afternoon and evening as a developing low in the northern Plains begins to build warm frontogenesis across central Wisconsin. An isolated shower is possible along the frontogenesis zone, but is not likely (~10% chance).

Overnight tonight, expect storms to develop upstream in Minnesota, progressing southeastward through the warm frontal region into central Wisconsin. Main hazard with these storms at this time is expected to be lightning, as LLJ dynamics remain to the north and MUCAPE values only increase to a few hundred J/kg. Temperatures will remain in the upper 50s to low 60s through the overnight hours.

Going into Wednesday, expecting showers and storms to linger across central Wisconsin and spread into southern Wisconsin as low pressure begins to propagate southeastward into northern Wisconsin. The warm front from this low will finally progress eastward through southern Wisconsin midday Wednesday, with strong southwesterly winds developing behind it. This will allow for destabilization across especially southwestern to south-central Wisconsin as temperatures rise into the upper 70s to near 80 degrees. SBCAPE on mesoscale models is pushing 2000 J/kg with the 00Z runs, while globals remain modest around 1500 J/kg. With instability and shear increasing (0-6 km shear around 45-50 kt and 0-3 km shear around 25 kt) in the afternoon hours, expecting some storms to become severe as a final cold front sweeps through the region late in the afternoon into the evening hours. With strong offshore flow, severe potential exists all the way to Lake Michigan. Main hazards at this time look to be damaging winds and hail within stronger storms.

The cold front pushes south of the WI/IL border Wednesday night as low pressure exits into Michigan. Expecting storms to weaken around sunset, with drying conditions overnight. Winds may weaken enough to allow for ground fog to develop, especially in southwestern Wisconsin. Expect lows in the mid-50s.

MH

LONG TERM

Issued 124 AM CDT Tue Jun 23 2026

Thursday through Tuesday:

Low pressure stalls over Michigan on Thursday, bringing a final wave of isolated to scattered showers and storms (20-35% chances) across southeastern to central Wisconsin. Meanwhile, low pressure develops in the southern Plains while high pressure builds over Ontario, bringing dry conditions to southern Wisconsin Thursday night through Friday. Temperatures return to seasonal norms into the weekend as low pressure deepens across the northern Plains and brings additional warm frontogenesis to the Upper Mississippi Valley. Precipitation chances return Saturday night into Sunday night as well as low pressure lifts into Ontario, but models diverge on coverage and intensity (20-40%). As low pressure lifts farther north and high pressure builds across the Southeast U.S. Monday into Tuesday, stiff southwesterly winds will bring rising temperatures to southeastern Wisconsin. Potential for highs in the upper 80s to low 90s, however, widespread cloud cover from WAA precipitation (PoPs 20-35%) will likely modulate these temperatures away from the 90s. Still, hot and humid conditions are likely to start the work week.

MH

AVIATION

Issued 645 AM CDT Tue Jun 23 2026

Dry weather and VFR conditions through today, with light and variable winds. A localized lake-breeze circulation will develop along the Lake MI shoreline midday, pushing inland through the afternoon and evening (included in TAFs where applicable). Expect predominantly easterly flow behind that lake breeze front (northeast for the early phase of it, transitioning to due east and eventually southeast). Some 5,000-8,000 ft diurnal cumulus clouds might develop this afternoon; areas east of the lake- breeze boundary may see these clear out.

Shower and thunderstorm chances expected across the region late Tonight through Wednesday evening. Some locally stronger storms may occur Wednesday afternoon through early evening. A light south breeze develops tonight, veering southwest and accelerating into Wednesday.

Sheppard

MARINE

Issued 124 AM CDT Tue Jun 23 2026

High pressure around 30.2 inches over the Upper Midwest will bring light and variable winds throughout 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 ahead of developing strong low pressure in the northern Plains.

MH

MKX WATCHES/WARNINGS/ADVISORIES

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