NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 241753
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1253 PM CDT Mon Aug 24 2026

.KEY MESSAGES...

- High swimming risk at Sheboygan County beaches Tuesday
  afternoon and evening.

- Scattered showers & storms (~30-50% chances) possible Tuesday night
  areawide & once more Wednesday across the east. Can't rule
  out an isolated storm with gusty winds or hail.

- Rain-free & pleasant conditions late week.

- Trending active this weekend into early next week, with
  multiple periods of showers and storms forecast.

&&

.SHORT TERM...
Issued 1255 PM CDT Mon Aug 24 2026

This afternoon through Wednesday:

Synopsis/Mesoanalysis: High pressure is crossing southern Wisconsin
early this afternoon, resulting in mostly clear skies and pleasant
weather conditions. The high will continue east toward Lower
Michigan tonight, but will remain proximate enough to the area to
support another overnight period of light & variable winds. These
conditions could result in another round of fog development after
midnight, particularly in river valleys and other low-lying spots.
Slow down, use low beam headlights & allow for extra following
distance if encountering fog on the roads late tonight. Currently
approaching the Saskatchewan-Manitoba border, an upper disturbance &
affiliated surface low will progress southeast across the Lake
Superior vicinity Tuesday into Tuesday night, ultimately reaching
Lake Huron by Wednesday evening. The progressing features will pull
a warm front through southern Wisconsin Tuesday night, with a cold
front following closely behind Wednesday morning & afternoon.
Scattered showers & storms are possible along both frontal
boundaries. An isolated severe storm with hail or gusty winds can't
be entirely ruled out.

Tuesday Afternoon/Evening: Brief period of increasing winds and wave
heights will lead to hazardous swimming conditions at Sheboygan
County beaches. Beach Hazards Statement is now in effect between 4-
10 PM CDT given these expectations. Exercise extreme caution if
planning to head lakeside during this time frame.

Tuesday Night into Wednesday Morning: Expecting an initial batch of
scattered showers and storms areawide as warm advection increases in
the lower levels. Could see some activity fire as early as the 8 PM
to 12 AM timeframe, though expectations are for better potential
after midnight, when a deeper pull of warm/moist advection &
affiliated MUCAPE is progged to surge east into the area. Have
tweaked precip probabilities to reflect anticipated trends.
Consensus amongst global & high-res guidance is pointing toward ~20-
30 knots of deep layer shear being in place regionally, so a few
more organized storms capable of hail or gusty winds can't be
completely ruled out. Will be monitoring trends through tomorrow.

Wednesday Afternoon: Another conditional window of storm potential
is forecast as a cold front sweeps through the area. Best chances
for additional storms will be across the eastern half of the area,
where the cold front will arrive last. Any development will be
contingent on frontal timing, as well as sufficient atmospheric
recovery in the wake of early morning activity. Available guidance
portrays a wide range of scenarios regarding these factors, each
carrying different implications for storm coverage in southern
Wisconsin (if any at all). Have thus maintained ~30-50% precip probs
over the eastern third of the area given the lingering
uncertainties. If storm development occurs, an isolated severe storm
with hail or gusty winds would be possible once again.

Quigley

&&

.LONG TERM...
Issued 1255 PM CDT Mon Aug 24 2026

Wednesday through Monday:

Synopsis: High pressure will move into the western Great Lakes
during the second half of the week, leading to pleasant and mostly
dry weather conditions Wednesday night into Friday. The high will
shift east by Saturday, with returning southerly flow leading to
steady increases in humidity through the remainder of the weekend.
Concurrent increases in zonal upper level flow, embedded shortwaves,
and passing surface fronts will support the next shower and storm
chances within the returning moisture. Showers and storms could
begin as early as Saturday night, with additional periods of storm
potential continuing into Monday as humidity lingers across the
western Great Lakes. Windows of storm activity will be accompanied
by lull periods, with all-day washouts not anticipated.

Saturday Night through Monday: Shower and storm chances return amid
increasing warm/moist advection. Expecting initial periods of
activity to commence Saturday night through Sunday as the nose of
the low level jet approaches and ultimately folds over southern
Wisconsin, with a final period of storm development along a passing
cold front on Monday. A broad overlap of sufficient shear and
instability makes this a period to monitor for organized/stronger
thunderstorms, though whether these parameters come together to
realize any potential will depend on smaller-scale features & timing
not yet captured by available guidance. Precipitable water values
will be elevated through this period, so will also need to watch for
pockets of locally heavy rainfall. Will be monitoring trends &
providing additional info as this portion of the period draws
closer.

Quigley

&&

.AVIATION...
Issued 1255 PM CDT Mon Aug 24 2026

VFR flight categories prevail through the period at all southern
Wisconsin terminals. High pressure will progress east across the
area through this afternoon, keeping fair weather cumulus
development more suppressed relative to prior afternoons. Have
pulled any mentions of FEW/SCT clouds based between FL040 and FL060
from the near-term forecast at all fields. A brief period of east-
northeast winds is possible during the mid-late afternoon hours near
Lake Michigan as a lake breeze attempts to mix inland. Otherwise,
light and variable winds will continue into tonight as the high
continues eastward. South-southwest winds will re-establish Tuesday
morning as upper clouds begin to thicken near or just above
FL200.

Quigley

&&

.MARINE...
Issued 1255 PM CDT Mon Aug 24 2026

1007 mb low pressure remains nearly stationary over western Quebec
this afternoon, resulting in continued breezy northwest winds across
the open waters of Lake Michigan. The breezy conditions will
continue through through the remainder of the afternoon as the low
lingers over the same general vicinity. Currently centered from
western Lake Superior toward north-central Wisconsin, 1018 mb high
pressure will gradually work over Lake Michigan this evening,
bringing decreasing winds. Expect readings to become light and
variable near or just after sunset.

Light and variable winds will continue into tonight as high pressure
lingers over the western Great Lakes. The high will shift east into
Ontario tomorrow, resulting in a south-southwest wind shift across
the waters. 1005 mb low pressure will approach from the northern
Great Plains tomorrow night into Wednesday, reinforcing the south-
southwesterly wind pattern. The low will cross Lake Michigan during
the second half of the day Wednesday, bringing a breezy northwest
wind shift. Gales are not expected as this occurs. Showers and
thunderstorms will accompany the approaching/passing surface low
tomorrow night into Wednesday afternoon. Widespread severe weather
is unlikely in these storms, though an isolated stronger storm with
hail and gusty winds can't be ruled out. The next area of 1018 mb
high pressure will gradually build toward Lake Michigan from the
northern Great Plains Wednesday night through Friday, bringing
slowly decreasing winds. Shower and storm chances return this
weekend. Whether any storms will be severe remains uncertain, with
trends being monitored through this week.

A brief period (~6 hours) of Small Craft Advisory conditions is
expected Tuesday afternoon & evening to the north of Port
Washington. A Small Craft Advisory is now in effect between 4-10 PM
CDT from Port Washington to Sheboygan given these expectations.
Periods of showers and storms remain forecast tomorrow night into
Wednesday, with an isolated stronger storm with gusty winds and hail
possible. Storm chances return this weekend.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052...4 PM Tuesday to 10 PM
     Tuesday.

LM...Small Craft Advisory...LMZ643...4 PM Tuesday to 10 PM Tuesday.

&&

$$

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