NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 070601
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
101 AM CDT Sun Jun 7 2026

.KEY MESSAGES...

- A very humid airmass will return Monday and Monday night ahead
  of approaching low pressure with widespread showers and
  scattered thunderstorms forecast.

- Hot and humid conditions expected mid to late week, with some
  potential for Heat Advisory conditions and additional chances
  for showers and storms.

&&

.SHORT TERM...
Issued 1250 AM CDT Sun Jun 7 2026

Today and Tonight:

Broad high pressure over the Great Lakes and broad low pressure
over the Great Plains will drive a light east to southeasterly
breeze over southern WI today, with the onshore flow holding
eastern WI temperatures to the 70s, with inland highs in the
mid 80s. Similarly, the lake will limit / inhibit shower and
storm chances for eastern and central WI, while far southwestern
WI (Lone Rock to Monroe westward) observes a chance for showers
and thunderstorms this afternoon (30-60%). 30-50% shower and
storm chances spread northeastward late tonight ahead of an
approaching shortwave trough.

Sheppard

&&

.LONG TERM...
Issued 1250 AM CDT Sun Jun 7 2026

Monday through Sunday:

Synopsis:
The 300-250mb upper air pattern through this week will feature a
longwave trough over the northern rockies and ridge over the Great
Lakes region, with the axes of each slowly progressing eastward.
For Wisconsin (and the midwest in general) we can expect to see
several shortwave troughs (and surface pressure responses)
rippling through the east edge of the longwave trough from SW to
NE, yielding periodic chances for showers and thunderstorms. The
ridging and warm weather should peak mid-week (Wednesday),
followed by a slight cooling trend into next weekend.

Details:
The first 500mb shortwave trough slowly crosses WI Monday morning
through late Monday night, with one or more rounds of scattered
showers and thunderstorms expected to track northward across the
region through said timeframe (overall precip chances 85-95%).
Monday is not a 'complete wash' due to the off-and-on / showery
nature of this activity, but we're fairly confident that most
areas in southern WI will see at least some rainfall at some point
on Monday / Monday night (hence the high precip chances). A modest
southeast breeze off of Lake Michigan will limit instability over
much of southern WI, hence we do not currently anticipate any
strong to severe storms. The highest thunder potential would be
found over southwestern WI.

For Tuesday, models keep the 500mb isohypses fairly straight, and
the pattern free of noteworthy shortwaves. Hence, only 20-30%
chances for precip through the daytime hours, mainly in the event
the lake breeze were to initiate convection in far eastern WI. Of
course, this could change in future model runs. High temperatures
climb into the upper 80s to around 90, cloud cover decreases.
Precip chances climb to 25-40% late Tuesday night on account of
potential for a decaying storm complex to approach from the west
(depicted in the 12z ECMWF forecast).

The warmth should peak on Wednesday with high temperatures in the
low 90s possible. GEFS instability peaks on Wednesday as well,
with ~80% chances of reaching or exceeding 3,000 joules CAPE in
the afternoon. A 500mb shortwave may kick-off convection west of
our region Wednesday afternoon, with a chance for it to track east
and decay into our region Wednesday evening / night (45-80% precip
chances, highest further west). Note that a slight eastward shift
in the positioning of that trough (and the wind shear + convective
initiation) would yield a more substantial threat for organized /
strong storms tapping into the instability overhead. This is
something we'll have to watch for, but fortunately, the timing and
placement of initiation with the latest guidance suggests the
higher threat will be centered closer to Minnesota as opposed to
Wisconsin.

Deterministic GFS / ECMWF runs resolve a more potent 500mb
shortwave crossing our region Thursday, which could refocus the
wind shear + ascent over WI and yield a more potent severe weather
threat. Our precip chances for Thursday remain at ~60% due to
dispersion / uncertainty amongst the ensemble guidance. In other
words, this shortwave could time itself favorably with the diurnal
heating cycle, or unfavorably.

A gradual cooling trend is then expected late this week into next
weekend as the longwave trough builds in from the west.

Sheppard

&&

.AVIATION...
Issued 1250 AM CDT Sun Jun 7 2026

Dry weather and VFR continue through the rest of the overnight
hours. Some marine fog may develop over north central Lake
Michigan and drift towards the shoreline of east-central WI, but
should not affect eastern WI terminals.

There will be some 10-50% chances for a stray shower or
thunderstorm in far southwestern WI through this afternoon and
evening (southwest of all TAF sites, mainly KMRJ and KEFT
airports), with dry weather and continued VFR elsewhere. Shower
and storm chances will slowly build northeastward towards I-90
late tonight, then across the rest of the region Monday into
Monday night.

Sheppard

&&

.MARINE...
Issued 1250 AM CDT Sun Jun 7 2026

High pressure of 29.9 inches builds into the Upper Great Lakes
and strengthens to 30.1 inches overnight. Warm and humid air will
linger over the relatively cool waters of Lake Michigan, with a
plume of marine fog over north-central portions of the lake slowly
sagging southwestward overnight. A Marine Dense Fog Advisory
remains in effect for the northern 2/3 of the lake until midday
Sunday. Recent satellite observations suggest the extent /
intensity of the fog may be weaker than prior expectations,
hence the Advisory may be canceled early.

Light and variable winds (predominantly north to northeast)
continue throughout Sunday. Broad low pressure over the Great
Plains and high pressure over the northeastern CONUS will lead to
modest southeast winds over the lake late Sunday night through
Tuesday.

Occasional chances for showers and thunderstorms are in the
forecast, particularly late Monday through Monday night.
Additional chances later in the week.

Sheppard

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory...LMZ643 until 9 AM Sunday.

     Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ669-LMZ671-LMZ868-LMZ870-LMZ872 until 1 PM
     Sunday.

&&

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, X, and YouTube at:
www.facebook.com/NWSMilwaukee
www.x.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee