textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Warm but slightly below normal temps expected this weekend through early next week.

- Chance of showers for southern WI Sunday, but trending farther south toward the WI/IL border than previous forecast.

- Chances for showers and thunderstorms at times toward the middle of the week.

UPDATE

Issued 500 AM CDT Sat Jun 20 2026

No changes to the going forecast.

Sheppard

SHORT TERM

Issued 1220 AM CDT Sat Jun 20 2026

Today through Sunday night:

Behind tonight's shortwave trough passage, expect more westerly winds and drier airmass to settle across southern WI through the day as weak high pressure tracks across the area. Looking at daytime temps in the low to mid 70s under mostly sunny skies with overnight into early Sunday morning lows dip back into the mid to lower 50s as upper-level northwesterly flow sets up across the Upper Midwest.

Clouds then look to sneak back into the region for Sunday as a swath of unorganized mid-level vorticity is progged to track across the Corn Belt region. Accompanying this wave will be a surface low ejecting out from the lee of the front range of the CO Rockies across the Plains and through central IL/IN later Sunday. Continue to see a trend in the low and subsequently its warm front tracking/remaining farther south of WI resulting in prevailing easterly and cooler flow across out neck of the woods. high temps for sunday look to ranging from upper 60s to lower 70s.

While the southern trend becomes increasingly likely setup for the end of the weekend, expect to still see precip chances to develop on the cool side of the warm front as well as on the northside of the passing low as the moisture from the Gulf advects up the Mississippi River Valley with this system. However, thunderstorm chances continue to dwindle up in southern WI as models continue to prog the favorable instability to south of the WI/IL border along and south of the warm front more so in central to southern IL/IN. Additionally with the southern trend, northern and even central portions of the CWA may ultimately stay dry on Sunday given the drier air infringing further south as seen on the tail-end of the 00z HRRR. Nevertheless still looking at 30-60% chance for showers for the southern portions of the CWA toward the WI/IL border.

Additionally with the onshore flow off of Lake Michigan Sunday into the overnight hours, could see elevated swim risk conditions as winds pick up and waves build toward hazardous level.

Wagner

LONG TERM

Issued 1220 AM CDT Sat Jun 20 2026

Monday through Friday:

Continue to see fairly mild temps that will be slightly (3-10F) below normal through the weekend as upper-level northwesterly flow sets up across the region. This pattern looks to continue into the middle of the week before upper-level ridge attempts to build and temps warm closer to normal toward the later half of the week. Overall expecting a dry start of the week as high pressure builds down across the Upper Great Lake Monday and Tuesday. Then mid-range model continue to show an upper-level trough digging across the region later Tuesday into Wednesday. This will bring the next shot of showers and storms to southern WI. May see some of this activity linger into Thursday on the backside of the departing system, but otherwise looking at high pressure to build toward the end of the week accompanying the gradually warming trends into next weekend.

Wagner

AVIATION

Issued 500 AM CDT Sat Jun 20 2026

An arc of low clouds (around 1,500 to 2,500 ft) has managed to push southward into portions of east central WI early this morning (mainly KSBM), resulting in patchy MVFR. We expect these clouds to mix out and erode through the course of daytime heating. Hence, dry weather and VFR expected through today and tonight. A light northwest breeze is expected today, with calm winds tonight.

Sheppard

MARINE

Issued 1220 AM CDT Sat Jun 20 2026

Low pressure will works its way east overnight while high pressure begins to build into the region. Looking at lighter winds tonight through the early morning hours, but expecting to increase this afternoon in between the departing low and incoming high. Winds then shift more easterly for Sunday as another low pressure develops across the Plains and tracks across central IL/IN. The strengthening onshore flow will likely result in building waves and gusty winds around small craft levels for Sunday into Sunday night, especially toward the southern half of the Lake. Then lighter winds return for the start of the work week as high pressure treks across the area.

Wagner

MKX WATCHES/WARNINGS/ADVISORIES

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