textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Widespread frost and below freezing temps expected well inland from Lake Michigan tonight/Friday morning and again Friday night/Saturday morning. Frost Advisory and Freezing Warning in effect for portions of southern WI.

- Scattered showers lingering into the overnight hours along with clouds over ern WI. Additional pop-up isolated to scattered showers possible on Friday.

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

SHORT TERM

Issued 1124 PM CDT Thu Apr 30 2026

Tonight through Monday night:

Showers will linger over ern WI into the early morning hours as a shortwave trough moves ewd across nrn IL, and the associated inverted trough retreats sewd across the area. Another shortwave trough over Upper MI will slowly rotate across nrn Lake MI tnt- Fri AM, which may aid in keeping the cloud cover around over east central WI. In addition, the increasing moist low levels and weak cold advection on the back side of the inverted trough will likely lead to stratus clouds over ern WI into Fri AM. Cancelled the far ern portions of the Frost Advisory due to the greater than expected cloud cover and slightly milder temps.

For Fri afternoon, a region of AVA will move into sw WI and far srn WI, while vorticity maximums will continue to rotate through the Upper Fox Valley. Fcst soundings are marginally unstable and will continue to forecast 20-30 percent chances with highest chances over east central WI. High pressure will finally arrive for late Fri nt with higher confidence for clearing skies and widespread frost. Thus another Frost Advisory and/or Freeze Warnings will likely be needed.

For Sat, the high will quickly shift sewd with swly winds and warm advection beginning in the afternoon and continuing into Sun. This is in response to an approaching shortwave trough and wave of low pressure that will pass on Sun. The weekend will mark the beginning of a warming trend but also 20-30 percent chances for showers Sat nt-Sun.

Yet another stronger shortwave trough and deepening low pressure area will then track across far srn Canada, including the Lake Superior region on Monday. Swly winds will bring a brief return of 70 degree temps. The cold frontal passage will support 40 percent chances for showers at this time.

Gehring

LONG TERM

Issued 1124 PM CDT Thu Apr 30 2026

Tuesday through Thursday:

An increasingly cooler period is expected as 1000-500 thickness trough gradually deepens over the Upper MS River Valley and wrn Great Lakes. There are 20-30 percent chances for instability showers each day.

Gehring

AVIATION

Issued 1124 PM CDT Thu Apr 30 2026

Cigs of 3.5-6.0 kft and light rain lingering into the early morning hours will lead to areas of MVFR Cigs over ern WI for Fri AM. The Cigs will then rise to 3.5-4.0 kft by afternoon. For south central WI, Cigs will become scattered during the early morning hours then reform by Fri afternoon at 3.5-4.0 kft.

Gehring

MARINE

Issued 1124 PM CDT Thu Apr 30 2026

High pressure around 30.2 inches continues to sit over central Canada through the end of the week and will bring light and varying winds across Lake Michigan through Friday. High pressure begins to work its way southeastward tracking across Lake Michigan overnight Friday through the day Saturday. Will begin to see more southerly winds develop Saturday night and pick up into Sunday as the high pressure continues to track southward while low pressure around 29.4 inches treks across Ontario. This looks to drag a cold front week cold front across the lake later Sunday turning winds more westerly briefly, before another low pressure around 29.1 inches develops right behind it for Monday. Expecting a stronger cold front to move across the Lake through the day Monday and turn winds north-northwesterly overnight into Tuesday.

Gehring

MKX WATCHES/WARNINGS/ADVISORIES

WI...Freeze Warning...WIZ046-WIZ047-WIZ056-WIZ057 until 8 AM Friday.

Frost Advisory...WIZ051-WIZ058-WIZ062-WIZ063-WIZ064-WIZ067- WIZ068-WIZ069 until 8 AM Friday.

LM...None.