textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Isolated to scattered thunderstorms are possible late this afternoon and evening and again Friday evening.

- Additional shower chances return on Sunday (40-60%).

UPDATE

Issued 554 AM CDT Thu Jun 18 2026

Lingering light showers along and behind a frontal boundary will wind down early this morning, with dry weather expected mid- morning through at least early afternoon. Should be enough clearing this afternoon for some instability to build. Maintained the 20-30 percent chances for showers and storms late afternoon into the evening.

DDV

SHORT TERM

Issued 1145 PM CDT Wed Jun 17 2026

Rest of Tonight through Friday:

Low pressure will continue to track east across the central portions of Lake Michigan overnight and into far eastern Ontario and Quebec Thursday morning. This will allow for low clouds to persist overnight through the early morning hours before lifting after daybreak. Clouds will insulate temps and looking at lows for early morning to hold in the mid 50s.

For thursday expect northwest to westerly winds on the backside of the departing low. Expect lingering cloud cover and temps only climbing into the lower 70s. May see a few isolated to squattered showers on the backside of the low as a mid-level shortwave trough swings through the area paired with a 30 knot LLJ later Thursday afternoon/early evening. Overall not expecting much from this activity other than a few sporadic rumbles of thunder and light showers. Also cannot completely rule out some small graupel and brief gusts of wind, but overall strong storm chances remain on the low side.

Friday will see lighter winds and slightly warmer temps during the day with mid to upper 70s highs as high pressure works its way across the region. Then looking at another mid-level shortwave trough to traverse across the Upper Midwest later Friday bringing a slug of moisture and PWATs increasing to around and above 1 inch. Thus looking at another potential for some showers across southern WI. Some of the mid-ranghe models hint at 200-900 J/kg of MUCAPE to works its way across the CWA during this time, thus a few rumbles of thunder will be possible as well with this activity Friday evening and diminishing overnight.

Wagner

LONG TERM

Issued 1145 PM CDT Wed Jun 17 2026

Saturday through Wednesday:

Weak cold advection will be ongoing on Sat in the wake of weak low pressure and a shortwave trough. 500 mb height rises and a weak sfc ridge will then take hold later in the day and Sat nt. Slightly below normal temps are forecast.

A shortwave trough and low pressure area is then expected to track from IA/MO across the nrn Ohio Valley Sun-Sun nt. There is uncertainty on the track and how far north the rain shield will spread. At this time 30 percent chances for rain is forecast toward central WI increasing to 60 percent over far srn WI. Thunderstorms are not forecast at this time. The rain may linger into Sun nt.

Shortwave ridging aloft along with sfc ridging will then prevail for Mon into Tue with pleasant summer high temps remaining in the 70s. A shortwave trough will then approach from the northwest for Tue nt-Wed. There also is uncertainty on the strength and timing of this upper wave. 30-50 percent chances for showers are forecast at this time along with small chances for storms.

Gehring

AVIATION

Issued 554 AM CDT Thu Jun 18 2026

Lingering light showers along and behind a frontal boundary will wind down early this morning, with dry weather expected mid- morning through at least early afternoon. Should be enough clearing this afternoon for some instability to build. Maintained the 20-30 percent chances for showers and storms late afternoon into the evening.

Conditions should return to VFR by late morning given daytime mixing resulting in higher cloud bases and general clearing of expected cloud cover. Mostly clear skies are then expected tonight into Friday, with another round of shower and storm chances in the late afternoon and evening.

DDV

MARINE

Issued 1145 PM CDT Wed Jun 17 2026

Low pressure will track across central portions of the lake tonight. With the tight pressure gradient will see gusty northeast to northerly winds across the northern third of the lake and gusty southwest to west winds for the southern third. Occasional gusts up to 30 knots possible, especially for the southern portions of the lake. Then as the low pressure exits into Michigan early Thursday morning, expect all winds to shift to the northwest and diminish gradually through the day. Winds remain light and northwesterly through Friday as high pressure progresses southeastward into the Lower Mississippi Valley. Winds may briefly turn southwesterly Friday night as weak low pressure moves through the region, but high pressure will rapidly regain dominance by Saturday, keeping winds light and variable. Stronger low pressure will approach from the central Plains on Sunday, bringing more widespread rain and thunderstorms and turning winds to northeasterly, which will continue into early next week.

Wagner

MKX WATCHES/WARNINGS/ADVISORIES

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