textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Scattered thunderstorms from late afternoon through late tonight. A few stronger storms will be capable of large hail. The recent rain and additional half inch to inch tonight may cause localized flooding through Saturday morning.

- Seasonal temps and dry Sunday into early next week.

UPDATE

Issued 636 AM CDT Fri Apr 3 2026

Drizzle is ongoing early this morning over portions of southern WI. There is subtle lift in the low levels due to weak warm air advection, and the moisture is trapped beneath a strong inversion. Most of the morning will be dry and winds will become light and variable for a time. Low pressure approaching from the Northern Plains will bring our next round of showers and thunderstorms. This system is associated with an occluded upper low that will cross South Dakota today into this evening, but the leading edge of it, well out ahead of the parent low, will tap into vorticity advection over the Plains and Gulf moisture and develop a surface low over MO and IA today.

The low levels of the atmosphere in southern WI will be in cool and moist easterly flow this afternoon and evening, while warm, moist air flows up and over us. This is a good setup for slow- moving rain showers. Given the strong warming aloft, we also have elevated instability. Most unstable CAPE is expected to remain under 1000 j/kg in southern WI through tonight, and the shear profile is not terribly impressive in the unstable layer, but a few stronger storms are possible and hail up to 1" is a threat. Southern WI remains in a Marginal Risk for Severe from SPC and this seems reasonable.

With 0.75 to 2 inches of rain falling yesterday and another half to one inch of rain expected today, localized flooding in streets, creeks, ditches, and other low lying areas is possible.

Showers with embedded, elevated thunderstorms will spread into central and portions of south central WI late this afternoon, mainly staying northwest and north of Madison to West Bend until mid evening. Then scattered showers and storms will become more widespread across southern WI between 9 and 11 PM. A line of storms will track across the area between 11 PM and 2 AM, then exit and only a few light showers will remain through the overnight hours. Westerly winds will increase Saturday as the parent low travels across the Upper Great Lakes, and some wrap- around showers are possible Saturday afternoon and evening.

Cronce

SHORT TERM

Issued 1241 AM CDT Fri Apr 3 2026

Today through Saturday night:

Temps will continue to fall through this morning behind the cold front with lingering cloud cover. However, post-cold front conditions will not last long as another upper-level trough is progged to dig across the Plains during the day on today. This looks to bring a weak surface low up from the front range of the CO Rockies through MO an overhead of WI. Most models are in agreement on this track, which keeps southern WI generally in the easterly surface of this system. However, given the 850mb WAA paired with the mid-level vorticity and nose of 35-40 kt LLJ looks to be enough forcing to tap in the elevated CAPE later Friday evening into early Friday morning. 00z HREF progs mean MUCAPE values of 500-1000 J/kg to nose into southern portions of the area and pair with +40 kt of deep shear looks to be enough for a few strong to severe thunderstorms for late this evening into Saturday morning. Mainly looking at hail up to around an inch given the elevated nature of the environment, but cannot completely rule out a strong gust punching through the low-level stable enough, especially for areas along the WI/IL border and if the the warm front lifts a bit further north. Overall, it will be scattered coverage and much of the activity wrapping up by 09z-12z.

Another thing to keep an eye on is the rainfall and potential for localized ponding and flooding. much of southern WI picked up around 1-2 inches of rain yesterday, and additional rain persisting over areas that saw heavier rainfall today will be susceptible.

Otherwise, Saturday will see additional light scattered showers during the day at time with the wrap around of the departing low and with the mid-level trough.

Wagner

LONG TERM

Issued 1241 AM CDT Fri Apr 3 2026

Sunday through Thursday:

After a fairly active pattern Sunday through the start of next week looks fairly quiet as high pressure builds in behind the late week low. Influence from this high persist through Tuesday and will bring seasonal temps and mostly dry conditions. Then the pattern becomes more active by the middle of next week with a trough projected to dig across the central CONUS. Thus increased PoP chances return Wednesday into the end of the week, but may also see warmer temps as well.

Wagner

AVIATION

Issued 636 AM CDT Fri Apr 3 2026

MVFR ceilings will lift midday as winds shift to the east. Look for showers and thunderstorms to spread into central WI late this afternoon and across all of southern WI by mid evening. A few stronger storms will be capable of 1 inch hail. Expect MVFR ceilings and visibility to return with the storms, and IFR ceilings will develop as the rain ends overnight.

Cronce

MARINE

Issued 636 AM CDT Fri Apr 3 2026

Westerly winds will diminish through late morning as a weak surface ridge passes over the lake. Winds will then become northeasterly by this evening as a weaker low pressure around 29.8 inches occludes and crosses central Lake Michigan through early Saturday. A few easterly gale force gusts are possible over the northern end of the lake Saturday morning. Winds then veer southwesterly Saturday afternoon behind the surface low.

Westerly winds will persist through the weekend. A weak low pressure trough around 30.0 inches crossing Lake Superior and northern Lake Michigan will drag a cold front down the lake Monday afternoon. A brief period of brisk northerly winds is expected.

MKX WATCHES/WARNINGS/ADVISORIES

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