textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Chance for showers and thunderstorms for this evening (30-60%). Cannot rule out a stronger storm or two for areas along and west of I-39, but potential remains low.

- Chance of showers for southern WI Sunday, then again toward the middle of the week.

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

SHORT TERM

Issued 1235 AM CDT Fri Jun 19 2026

Today and Tonight:

High pressure will track to south and east of the area early this morning. This will bring clear, calm, and dry conditions with temps dipping down into the mid to lower 50s for the rest of tonight.

High pressure with continue to push eastward through this morning with light winds picking up through the afternoon and evening as weak low pressure track southeastward across WI through the evening along with a mid-level shortwave trough traversing across the Upper Midwest. Accompanying this wave will be a slug of Pacific moisture moving across the region and will allow for PWAT values to increase to around and even exceed 1 inch by this evening. Pair the moisture with mid-level dCVA and a 30-40 LLJ rounding the base of the trough and looks to be enough forcing to support shower development.

Main window for this activity will be late this afternoon through the evening. While there is ample synoptic forcing, there remains some questions on the instability as well as how quickly the moisture advects back into the area as most model prog only mid-50s dewpoints and 00z CAMs are suggesting below 500 J/kg of SBCAPE. However, still enough for a few rumbles of thunder, especially for areas along and west of the I-39 corridor. While mainly expecting showers and thunderstorms (30-60%), the latest CAMs are picking up on some 40-50 kt of deep layer shear and there are a few models that are more bullish with 500-1000 J/kg SBCAPE. If the more aggressive scenario pans out, then could see a few stronger storms develop with this system, which any taller/stronger storm will be capable of producing hail and gusty winds. Overall, the stronger storm potential remains on the lower side for our area as uncertainty on the moisture return, instability, along with all these factors aligning with the synoptic forcing will determine stronger convective development or not.

Wagner

LONG TERM

Issued 1235 AM CDT Fri Jun 19 2026

Saturday through Thursday:

Overall, extended period looks fairly mild with slightly below (5- 10F) normal temps. Will be a few opportunities for additional shower and thunderstorms for the end of the weekend and again toward the middle of next week.

Behind this evening's system will see drier airmass settle over southern WI as high pressure builds into the area through the weekend. Expect daytime temps in the mid to upper 70s for Saturday with mostly sunny conditions as the high pressure tracks across the Upper Great Lakes region.

Sunday will be our next chance for showers as models prog a surface low to track across central IL/IN. This looks to bring easterly flow off of Lake Michigan through the day and keep temps on the cooler side in the lower 70s. Given the latest model trends in the low track, this will keep southern WI on the cooler side of the system is likely to limit much of any instability to develop along with thunderstorms. Thus, Sunday is trending toward more of a widespread rainy day especially for the southern half of the CWA, while ares north may still see some rain and cloudy skies, there is a potential for drier air to the north limit shower development toward Central WI for Sunday, especially if we continue to the see the low track slightly farther south. Also could see elevated swim risk conditions with the easterly onshore flow for southern WI beaches on Sunday.

The start of the work week is looking to be dominated by high pressure build across the region with gradually warming temps. Then looking at another another shortwave trough to develop and dig across the Upper Midwest toward the middle of the week bringing additional shower and thunderstorm chances. Then for the later half of next week, upper-level ridging looks to build across the region toward next weekend.

Wagner

AVIATION

Issued 1235 AM CDT Fri Jun 19 2026

VFR conditions prevail tonight with light westerly winds into early morning hours. High pressure will quickly builds across the Midwest through morning maintaining VFR ceilings through much of the day. However, wind do look to pick up through the afternoon as the high skirt south and east with a weak surface low drift southeastward across WI through the evening bringing additional shower and thunderstorms chances. The best chances for thunderstorm will be for MSN and JVL, but more likely to see shower for the terminals further east closer to the Lake. With any shower/storm activity could see drops in ceilings and visibility to MVFR levels at times through the evening.

Wagner

MARINE

Issued 1235 AM CDT Fri Jun 19 2026

High tracking across the area this morning will bring lighter, westerly winds, but expect the winds to gradually pick up through the day as low pressure works its way southeastward across WI through the evening bring more southerly winds. Another High pressure and lighter winds expected for Saturday before another low pressure tacks across central IL/IN and turning winds more easterly. The strengthening onshore flow may see waves and winds build to small craft levels for Sunday along with showers across the southern half of the Lake and linger into the start of next week. Then lighter winds return as high pressure moves through for the start of next week.

Wagner

MKX WATCHES/WARNINGS/ADVISORIES

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