textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Areas of frost possible for central WI tonight/early Thursday morning, but more widespread frost potential will be possible both Thursday and Friday nights across much of southern WI.

- Daily scattered shower chances each afternoon through at least Friday.

- More active pattern early next week with increase showers and storm chances later Sunday through midweek.

SHORT TERM

Issued 210 PM CDT Wed Apr 29 2026

Tonight through Friday night:

Southern WI will continue to sit in upper-level northwesterly flow pattern with embedded ripples of mid-level vorticity passing through just about every day through the end of the week. Thus will see below normal temps and daily scattered shower and a few thunderstorm chances into Friday.

This afternoon seeing another mid-level vorticity ripple bring an additional round of lighter/persistent showers across much of southern WI. Overall QPF looks to be light generally less than a few tenths of an inch. While still cannot completely rule out a few isolated rumbles of thunder this afternoon as we see some bare minimum MUCAPE (50-150 J/kg) sneak into the area, the persistent stratiform rain is limiting overall chances. Otherwise, this shower activity looks to lift out over Lake Michigan through the early evening as this mid-level wave departs.

Overnight expecting some breaks in the clouds, especially for western half of the CWA. With any clearing paired with subsidence from surface high pressure and calm winds will allow temps to drop into the lower 30s and even upper 20s in a few low-lying spots across the Wisconsin river Valley, while mid to upper 30s are expected under any remaining cloud cover, especially toward Lake Michigan. Thus, patchy frost will be possible with more widespread development likely across central WI where a Frost Advisory has been issued for Sauk, Columbia, Marquette, Green Lake counties.

Thursday and Friday will see similar pattern with models projecting a few mid-level vorticity ripples pairing with enough moisture to spur a few scattered showers and storms chance during the daytime. Also expecting each night to experience chilly temps paired with light winds contributing to lows dropping into the the lower 30s and even upper 20s for Thursday night/early Friday morning and again Friday night/early Saturday morning. While still uncertain on cloud coverage each night, the signal continues for more widespread frost development and likely additional frost/freeze headlines will be possible for the next couple of nights heading into the weekend.

Wagner

LONG TERM

Issued 210 PM CDT Wed Apr 29 2026

Saturday through Wednesday:

Influence from the upper-level trough continues to shift east this weekend while the surface high pressure bringing the low- level northerly flow looks to finally kick east later Saturday. This should allow for more southerly surface winds and low-level WAA to build into southern WI toward the end of the weekend as a surface low develops north of the Great Lakes. This will bring in some milder temps as well as increased shower and thunderstorm chances later Sunday into Monday. This will be followed by a weak cold front, but things quickly recover into the start of the work week. Additional upper-level shortwave trough are progged to work their way through the region with additional shower/storm chances through middle of next week.

Wagner

AVIATION

Issued 210 PM CDT Wed Apr 29 2026

Persisting stratiform rain this afternoon is bringing MVFR ceilings to the the southern WI terminals closer to Lake Michigan, while MSN and JVL are seeing more sporadic cloud cover and shower chances with ceilings bouncing between MVFR and VFR. Still looks to be a narrow band of showers to impact these western terminals briefly through the late afternoon, while the others see more persistent light rain into the early evening hours. Expect northerly winds with occasional gusts of 10-20 kts until sunset, then light more variable winds along with drier continues and lifting ceilings overnight as high pressure gradually builds across the area. VFR linger into the morning, but expecting to see another upper-level wave to trek across the region through the day bringing another round showers to southern WI in the afternoon.

Wagner

MARINE

Issued 210 PM CDT Wed Apr 29 2026

High pressure over the northern Plains will gradually shift southeastward into the western Great Lakes by the end of the week. Northerly winds persist and gradually diminish through the evening. Winds will then remain lighter and variable through the end of the week. An isolated thunderstorm will be possible Thursday afternoon near the WI shore. High pressure will then slide southward into the Lower Mississippi Valley Sunday, shifting winds to westerly and increasing into early next week.

Wagner

MKX WATCHES/WARNINGS/ADVISORIES

WI...Frost Advisory...WIZ046-WIZ047-WIZ056-WIZ057...midnight Thursday to 8 AM Thursday.

LM...None.