NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 201004
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
504 AM CDT Sat Jun 20 2026

.KEY MESSAGES...

- Warm but slightly below normal temps expected this weekend
  through early next week.

- Chance of showers for southern WI Sunday, but trending farther
  south toward the WI/IL border than previous forecast.

- Chances for showers and thunderstorms at times toward the
  middle of the week.

&&

.UPDATE...
Issued 500 AM CDT Sat Jun 20 2026

No changes to the going forecast.

Sheppard

&&

.SHORT TERM...
Issued 1220 AM CDT Sat Jun 20 2026

Today through Sunday night:

Behind tonight's shortwave trough passage, expect more westerly
winds and drier airmass to settle across southern WI through
the day as weak high pressure tracks across the area. Looking at
daytime temps in the low to mid 70s under mostly sunny skies
with overnight into early Sunday morning lows dip back into the
mid to lower 50s as upper-level northwesterly flow sets up
across the Upper Midwest.

Clouds then look to sneak back into the region for Sunday as a
swath of unorganized mid-level vorticity is progged to track
across the Corn Belt region. Accompanying this wave will be a
surface low ejecting out from the lee of the front range of the
CO Rockies across the Plains and through central IL/IN later
Sunday. Continue to see a trend in the low and subsequently its
warm front tracking/remaining farther south of WI resulting in
prevailing easterly and cooler flow across out neck of the
woods. high temps for sunday look to ranging from upper 60s to
lower 70s.

While the southern trend becomes increasingly likely setup for
the end of the weekend, expect to still see precip chances to
develop on the cool side of the warm front as well as on the
northside of the passing low as the moisture from the Gulf
advects up the Mississippi River Valley with this system.
However, thunderstorm chances continue to dwindle up in southern
WI as models continue to prog the favorable instability to
south of the WI/IL border along and south of the warm front
more so in central to southern IL/IN. Additionally with the
southern trend, northern and even central portions of the CWA
may ultimately stay dry on Sunday given the drier air infringing
further south as seen on the tail-end of the 00z HRRR.
Nevertheless still looking at 30-60% chance for showers for the
southern portions of the CWA toward the WI/IL border.

Additionally with the onshore flow off of Lake Michigan Sunday
into the overnight hours, could see elevated swim risk
conditions as winds pick up and waves build toward hazardous
level.

Wagner

&&

.LONG TERM...
Issued 1220 AM CDT Sat Jun 20 2026

Monday through Friday:

Continue to see fairly mild temps that will be slightly (3-10F)
below normal through the weekend as upper-level northwesterly
flow sets up across the region. This pattern looks to continue
into the middle of the week before upper-level ridge attempts to
build and temps warm closer to normal toward the later half of
the week. Overall expecting a dry start of the week as high
pressure builds down across the Upper Great Lake Monday and
Tuesday. Then mid-range model continue to show an upper-level
trough digging across the region later Tuesday into Wednesday.
This will bring the next shot of showers and storms to southern
WI. May see some of this activity linger into Thursday on the
backside of the departing system, but otherwise looking at high
pressure to build toward the end of the week accompanying the
gradually warming trends into next weekend.

Wagner

&&

.AVIATION...
Issued 500 AM CDT Sat Jun 20 2026

An arc of low clouds (around 1,500 to 2,500 ft) has managed to
push southward into portions of east central WI early this
morning (mainly KSBM), resulting in patchy MVFR. We expect
these clouds to mix out and erode through the course of daytime
heating. Hence, dry weather and VFR expected through today and
tonight. A light northwest breeze is expected today, with calm
winds tonight.

Sheppard

&&

.MARINE...
Issued 1220 AM CDT Sat Jun 20 2026

Low pressure will works its way east overnight while high pressure
begins to build into the region. Looking at lighter winds tonight
through the early morning hours, but expecting to increase this
afternoon in between the departing low and incoming high. Winds then
shift more easterly for Sunday as another low pressure develops
across the Plains and tracks across central IL/IN. The strengthening
onshore flow will likely result in building waves and gusty winds
around small craft levels for Sunday into Sunday night, especially
toward the southern half of the Lake. Then lighter winds return for
the start of the work week as high pressure treks across the
area.

Wagner

&&

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

$$

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