NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 010424
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1124 PM CDT Thu Apr 30 2026

.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.
&&

$$

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