NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 260410
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1110 PM CDT Sat Apr 25 2026

.KEY MESSAGES...

- More low clouds and fog are possible overnight into Sunday
  morning in eastern portions of the area, possibly lingering
  into the afternoon.

- Highs into the upper 60s well inland Sunday, with cooler 50s
  closer to Lake Michigan with onshore winds.

- Widespread showers (80 to 100 percent chances) and scattered
  thunderstorms return for Monday through Monday night. There is
  the potential for severe weather, with locally heavy rainfall
  also possible.

- Cooler temps Tuesday through the end of next week, with a
  frost/freeze potential by the end of the week.

&&

.SHORT TERM...
Issued 1110 PM CDT Sat Apr 25 2026

Overnight through Sunday night:

High clouds will continue to push through the area overnight
into Sunday night. There is the potential for more low stratus
and fog to develop overnight into Sunday morning for eastern
portions of the area. Light onshore winds and lingering low
level moisture under the inversion should help support this
development.

One caveat will be the high clouds moving through at times,
which may limit the extent of the low clouds and fog. Enough of
the short term models are showing the low clouds and fog pushing
onshore to leave it in the forecast overnight into Sunday
morning for now. There is some potential for this to linger into
the afternoon as well. Cannot rule out locally dense fog moving
onshore, though this potential will need to be monitored.

Otherwise, easterly winds today, with more northeast winds near
the lake, are expected. Mild highs into the upper 60s are
expected well inland, with 50s closer to Lake Michigan.

East southeast winds should gradually increase Sunday night, as
the precipitation ahead of the next low pressure system
approaches from the west. Kept gradually increasing PoPs (20 to
40 percent in the western parts of the area) for later Sunday
night.

Wood

&&

.LONG TERM...
Issued 1110 PM CDT Sat Apr 25 2026

Monday and Monday night:

An upper trough crossing the Colorado Rockies will take on a
negative tilt over the Plains Monday morning as it aligns with a
coupled upper jet. As the system approaches, the low level jet
will actually increase over the state of WI during the day Monday.
There is still some degree of uncertainty in the strength of the
cyclogenesis, which will affect the track of the surface low and
also the placement of the warm front. The other factor for the
warm frontal location is where any morning convection tracks.

As the mid level vorticity and low level jet push into southwest
WI early Monday morning, the upstream storms have a chance to keep
hold together. Depending on the speed of the system, these
anticipated early morning storms could zip northward from
central/eastern IA into central WI OR cross southern WI. A slower
solution would keep srn WI in a more unstable environment.

With persistent warm air advection and vorticity advection,
scattered thunderstorms will be likely for much of the day. Strong
0-3km and 0-6km shear will be high (southwest 35-45kt for 0-3 and
even stronger bulk) due to the southeast winds at the surface and
south winds just above it. Steepening mid level lapse rates with
the mid level trough will help to increase the CAPE values in the
afternoon, but they should only top out around 1000 j/kg. A high-
shear-low-cape environment is conducive for damaging winds and
brief spin-up tornadoes (QLCS tornadoes), depending on how
organized and strong the storms get. The higher 925mb theta-e
values just south of the IL border which would favor the more
widespread convection to focus there.

It will be a windy day Monday, breezy out of the southeast with
gusts over 30 mph. High temperatures will depend on how much
sunshine and how far north the warm front can push, but around 70
inland from Lake Michigan is a reasonable forecast at this time. By
mid Monday evening, the surface low and area of thunderstorms
should be clear of southeast WI. However, the upper trough will
still be positioned over MN, so the chance of showers and maybe a
few rumbles of thunder will linger in southern WI until the trough
clears Tuesday morning. Repeated rounds of storms will bring a
risk for greater than 2 inches of rain, and the location with
the higher risk (20 to 30%) is south central and southeast WI
at this time.

With the system becoming slightly occluded during the
afternoon/evening Monday, the severe chances for southern WI seem
a little disjointed and the strongest convection may end up
splitting around the majority of our area. That said, shifts in
the system's evolution are still a very real possibility. The CIPS
analogs are showing similar scenarios to other severe outbreaks,
but looking at those individual cases reveals a more negatively
tilted upper trough that is not occluding when it crosses the
Upper Midwest. Keep up with the forecast.

Tuesday through Friday:

Gusty west winds will ensue Tuesday behind the front and highs
should only reach around 60. We are going to shift into a cooler
weather pattern for the week with highs in the upper 50s to around
60 Wed-Fri. This is due to an upper trough lingering over eastern
Canada and the northeast states with WI in northwest flow. Precip
chances will be minimal during this time.

Cronce

&&

.AVIATION...
Issued 1110 PM CDT Sat Apr 25 2026

High clouds will continue to push through the area overnight
into Sunday night. There is the potential for more low stratus
clouds and fog to develop overnight into Sunday morning for
terminals closer to Lake Michigan. Ceilings should be in the
500 to 900 foot AGL range, with visibility of 1 to 2 miles or
so.

One caveat will be the high clouds moving through at times,
which may limit the extent of the low clouds and fog. Enough of
the short term models are showing the low clouds and fog pushing
onshore to leave it in the TAFs for terminals near Lake Michigan
starting around 09Z Sunday into Sunday morning for now. There
is some potential for this to linger into the afternoon as well.
Cannot rule out locally dense fog moving onshore, though this
potential will need to be monitored.

Otherwise, easterly winds today, with more northeast winds near
the lake, are expected. East southeast winds should gradually
increase Sunday night. Low level wind shear conditions may
develop later Sunday night, though potential is borderline so
left out of TAFs for now.

Wood

&&

.MARINE...
Issued 1110 PM CDT Sat Apr 25 2026

East to northeast winds are expected to develop overnight into
Sunday, as high pressure around 30.2 inches shifts eastward into
southeast Ontario. Low pressure around 29.4 inches is then
expected to move from northeast Kansas early Monday to Lake
Superior by early Tuesday morning. Winds will increase Monday
into Monday night out of the south to southeast ahead of the
low.

The cooler lake temperatures may limit widespread gales across
the lake during this time, but a few gale force gusts are
possible. Breezy west to northwest winds will then develop
behind the departing low by later Tuesday. Lighter winds should
then occur into the rest of next week.

Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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