NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 031845
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
145 PM CDT Mon Aug 3 2026

.KEY MESSAGES...

- Beach Hazards Statement in effect Tuesday afternoon-evening at
  Sheboygan County beaches.

- Periods of showers and storms expected Tuesday afternoon into Wednesday.
  Storms could produce heavy downpours. An isolated severe
  storm is possible Tuesday afternoon-evening.

- Heat & humidity return by this weekend, along with periods of
  showers and storms.

&&

.SHORT TERM...
Issued 150 PM CDT Mon Aug 3 2026

Tonight through Wednesday night:

Synopsis/Mesoanalysis: High pressure is centered over Lake Michigan
this afternoon, resulting in light winds across southern Wisconsin.
Beneath ample sunshine, daytime heating has allowed for fair weather
cumulus development areawide, with the deepest & most concentrated
cloud cover along a weak lake breeze in southeast Wisconsin. Well to
the north & west of the region, surface analyses place a slow-moving
cold front from the International Falls, MN vicinity back into the
Black Hills. The boundary will gradually move east into the Upper
Mississippi Valley tonight, ultimately encroaching upon southern
Wisconsin either late Tuesday afternoon or Tuesday evening. The
boundary is expected to stall/wash out near or just south of the
Wisconsin-Illinois during the day on Wednesday. With the front in
the vicinity, periods of showers and thunderstorms are thus
anticipated from late Tuesday afternoon through Wednesday across the
region. An isolated severe storm with strong winds can't be ruled
out Tuesday afternoon, particularly if the front arrives during peak
heating. Wednesday's storm potential will depend on the positioning
of the front in the wake of Tuesday's storms, which remains a source
of uncertainty in this forecast. Any storms developing during the
Tuesday-Wednesday period will be capable of producing heavy
downpours, which could lead to localized flooding impacts in any
locations where storms train.

Tonight: Could see some fog development in the Wisconsin River
Valley near/after midnight, with more fog development across the
rest of southern Wisconsin more uncertain given steadily increasing
wind speeds. Have kept fog mentions confined to the Wisconsin Valley
in the afternoon update given the anticipated increase in wind
speeds, but will be monitoring trends through this evening. If winds
stay lighter for a longer time period than currently forecast, an
increase in fog coverage would become favored. Slow down & allow for
extra following distance if encountering areas of fog late tonight.

Tuesday Afternoon-Night: Wave heights will become hazardous at
Sheboygan County beaches, where a Beach Hazards Statement is now in
effect between 2-10 PM CDT. Exercise extreme caution if heading
lakeside. Shower and storm potential will increase from late
afternoon into the evening/overnight along the approaching surface
front. In the event the boundary arrives during peak heating, could
see an isolated severe storm with damaging winds. More
widespread/organized severe weather potential will be limited by
front-parallel upper level winds & marginal shear, which will
quickly favor an outflow-dominated & messy storm mode. Heavy
downpour potential, however, will need to be watched closer given
modeled precipitable water values approaching/exceeding 2 inches.
Said downpours could bring localized flooding impacts in any
locations seeing training storms. If & where any training
materializes remains a source of disagreement in current CAM
guidance, with trends being monitored for updates over the next 12-
24 hours.

Wednesday Afternoon-Evening: If the surface front is still lingering
over southern Wisconsin in the wake of Tuesday's storms, could see
another batch of shower & storm development across parts of the
area. Have largely maintained precip probabilities from the NBM in
the afternoon update, which depict the highest potential for
additional precip over south-central and southeast Wisconsin (the
most likely locations to still be in close proximity to the front).
In the event Tuesday afternoon-night's storms shunt the front into
Illinois, precip chances would decrease considerably. Expect further
refinements to precip probs as frontal placement clarifies in coming
forecasts. Expecting Tuesday + Wednesday storm total rainfall to be
0.25-1.00" in most locations, with pockets of locally higher
(2.00"+) totals wherever any training materializes.

Quigley

&&

.LONG TERM...
Issued 150 PM CDT Mon Aug 3 2026

Thursday through Monday:

Synopsis: Post-frontal surface flow will allow modestly drier air to
settle into southern Wisconsin on Thursday. The break in humidity
will be short-lived, however, as subtropical high pressure lingering
off the Mid-Atlantic coast allows large-scale flow to shift south-
southwesterly regionally into the weekend. Thus anticipate
increasing dew points & humidity regionally from Friday through at
least Sunday. Increasing humidity will be accompanied by a northward-
returning warm front, which is forecast to stall somewhere from the
Northern Plains to the western Great Lakes by Sunday. Arrival of the
boundary, along with increasing zonal flow in the upper levels, will
thus open the door for periods of thunderstorms Saturday night
through the conclusion of the long term. Batches of storms will be
accompanied by windows of dry conditions, with all-day washouts not
anticipated. While long lead-time makes it difficult to offer
precise details, building humidity & increasing winds aloft could
support some potential for more organized/stronger storms with heavy
downpours during the Saturday night-Monday time frame. Will be
monitoring trends through this week and providing additional
information as details become clearer.

Saturday night through Monday: With a quasi-stationary surface front
in the vicinity & increasing jet dynamics aloft, the broad pattern
will become favorable for periods of thunderstorms across the
western Great Lakes. Relative stability of the large-scale pattern--
-namely the quasi-stationary nature of the surface front & a
 flat/static height field in the upper levels---points toward
 multiple batches of storm development through this portion of
 the period. Where exactly each batch of development occurs will
 depend on placement of the surface front, the nose of the low
 level jet, and smaller scale features stemming from prior
 periods of storm activity. Expect some of these details to
 clarify by the end of the week. Building instability/moisture &
 increasing wind shear point toward some broad potential for
 more organized storms with heavy downpours, though finer
 details won't become clearer until later in the week. Stay
 tuned to later forecast updates. In addition to storm
 potential, do expect heat indices to become elevated once more
 during this time period. Whether/not heat headlines will become
 necessary remains uncertain, as clouds/storms could interfere
 with heat indices being maximized.

Quigley

&&

.AVIATION...
Issued 150 PM CDT Mon Aug 3 2026

Primarily VFR flight categories prevail through the period across
southern Wisconsin. SCT to BKN clouds based between FL025 and FL040
will continue through this afternoon/peak heating of the day, with
lowest CIGs anticipated in the immediate vicinity of a lake breeze.
Have accounted for these trends in the 18Z update, which includes a
period of prevailing MVFR in the vicinity of ENW through 20Z. Have
withheld any mentions of MVFR at MKE, as satellite imagery shows the
deepest cumulus to the west of the terminal, with westward motion of
the lake breeze pulling the deep cu field progressively further away
through the rest of the afternoon. Will nevertheless be monitoring
trends & amend if necessary. Cumulus will dissipate after sunset
this evening, with winds shifting west-southwest during the
overnight hours. Upper clouds based between FL150 and FL250 will
gradually thicken during the day on Tuesday. TSRA enter the forecast
later Tuesday afternoon along a slow-moving surface front, with
impacts in the vicinity of MKE possible nearing the conclusion of
the 30 hour forecast period. Have accounted for this potential with
a PROB30 group in the 18Z update. Mentions will become necessary at
other terminals in the coming 00 and 06Z forecasts.

Quigley

&&

.MARINE...
Issued 150 PM CDT Mon Aug 3 2026

1018 mb high pressure is crossing the open waters this afternoon,
resulting in light and variable winds. Winds will trend southerly
tonight into Tuesday as the high shifts east and a cold front moves
into the western Great Lakes. Said front will slowly move across
Lake Michigan late Tuesday afternoon through Wednesday, bringing a
brief north-northwest wind shift across the open waters. Periods of
showers and storms will accompany the slow-moving front, with severe
weather appearing unlikely at this time. Winds will trend variable
once more Wednesday evening through Thursday, when 1016 mb high
pressure is forecast to build back into the western Great Lakes.

A prolonged period of south-southwest winds will become established
across Lake Michigan Thursday night through Sunday as 1020 mb high
pressure lingers off the Mid-Atlantic coast and 1002 mb low pressure
stalls over the Hudson Bay. Shower and storm chances return to the
forecast Saturday night into the beginning of next week.

Increasing southerly winds will result in elevated winds and waves
in nearshore zones Tuesday, particularly from Port Washington &
points north. A Small Craft Advisory has been issued between 2-10 PM
CDT from Port Washington to Sheboygan given this potential. Periods
of showers and thunderstorms are expected along a slow-moving cold
front Tuesday afternoon into Wednesday, with severe weather
appearing unlikely at this time. Additional chances for showers and
storms return Saturday night into early next week.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052...2 PM Tuesday to 10 PM
     Tuesday.

LM...Small Craft Advisory...LMZ643...2 PM Tuesday to 10 PM Tuesday.

&&

$$

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