NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 020036
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
736 PM CDT Sat Aug 1 2026

.KEY MESSAGES...

- Breezy northeast winds will lead to high waves and dangerous
  currents at Lake Michigan beaches this weekend. A Beach
  Hazards Statement is in effect today through Sunday night for
  all Lake Michigan beaches. Stay out of the water!

- Next chances for thunderstorms Tuesday night through Thursday.

&&

.UPDATE...
Issued 736 PM CDT Sat Aug 1 2026

Light rain will continue to taper off across the southeast,
while isolated showers and thunderstorms affect Green Lake
through Lafayette Counties for the next hour or two. With plenty
of low level moisture lingering overnight, expecting local fog
to develop in low lying areas, and low clouds to develop
elsewhere. Expect lows in the low 60s.

MH

&&

.SHORT TERM...
Issued 200 PM CDT Sat Aug 1 2026

Rest of Today through Sunday:

Low pressure over south-central Illinois continues to yield some
wrap-around precip (light to moderate rainfall) over south-
central and southeastern WI, which should taper off from west to
east through the rest of this afternoon. Satellite imagery
reveals some towering cumulus clouds with isolated rainshowers
beginning to develop over central portions of the state, our
forecast leaves some ~15% chances for this activity to build
into areas north and west of Madison where some sunshine is
making it through this afternoon. Elsewhere, this type of
redevelopment is unlikely. Hence, predominantly dry weather
across the CWA this evening.

HRRR and RAP forecast soundings hint that low-stratus clouds
(or perhaps surface-based Fog) are likely to arrive/develop in
a northeast to southwest manner late tonight into early Sunday
morning. With the rain-humidified airmass, northeast low-level
winds, and potential for gaps in the synoptic cloud cover this
evening, this solution makes sense.

High pressure settles into the upper Great Lakes on Sunday,
helping to clear out any low-stratus (or fog) that may have
formed and leaving mostly clear skies through much of the
afternoon and evening. The north to northeast breeze will
continue, becoming gusty once again for the Lake Michigan
shoreline Sunday afternoon. The gusty winds and building waves
will allow the High Swim Risk to continue for Lake MI beaches
through late Sunday night, with high waves, rip currents, and
longshore currents all contributing to the dangerous conditions.

Sheppard

&&

.LONG TERM...
Issued 200 PM CDT Sat Aug 1 2026

Sunday night through Saturday:

High pressure will linger over the region Sunday night through
Tuesday, leading to mostly clear skies and dry weather. Weak
synoptic winds expected, with localized light lake breezes over
far eastern WI. Clear and calm nights should allow overnight lows
in the 50s (locally warmer by the lake), with daytime highs around
80 Monday trending up into the low 80s Tuesday (locally cooler by
the lake).

Low pressure develops over the central Great Plains Tuesday,
working with the aforementioned high pressure (departed east) to
hold the relatively warm and somewhat humid airmass in place over
much of WI (dewpoints in the 60s). Meanwhile, deep low pressure
over Hudson Bay drags a SW to NE oriented cold front into the
Midwest. This frontal boundary should bisect WI at some point
Tuesday PM, and though it's surface wind field and baroclinicity
may begin to wash out, it phases with an approaching longwave
trough in the upper jet, with some speed divergence overspreading
it. As such, we could see a broken line of showers and
thunderstorms along it, tracking southeastward into southern WI
Tuesday evening into Wednesday (overall precip chances 40-60%).
Ensemble estimates of CAPE in advance of the front Tuesday evening
range anywhere from around 1,000 to 2,000 joules, though the
modeled positioning of the frontal boundary + QPF + wind shear
reveal the convection may lag behind the peak instability,
firing in northern / central WI early evening and arriving later
Tuesday night for Southern WI. As such, there is no organized
potential for strong to severe storms with the front at this
time, but we will continue to monitor. Similarly, the current
timing for the front and precip would leave Wednesday morning
cloudy with rain chances. But, depending on the first wave of
activity, a relatively dry and cloud free morning on Wednesday
could allow airmass recovery for convection Wednesday afternoon
and evening (a scenario shown in a couple ensemble members).

From Wednesday night through late next week, the baroclinic zone
is forecast to remain nearby, and the upper air pattern shifts
slightly east allowing for stronger (40-50kt) bulk shear values
to arrive. Occasional shortwave troughs and jet entrances pass by,
giving merit to 10-35% chances for showers and storms. The
stronger shear could enable stronger storms, but timing of the
trigger mechanisms with peak diurnal instability would be required
for any organized severe threat.

Sheppard

&&

.AVIATION...
Issued 736 PM CDT Sat Aug 1 2026

IFR conditions under lingering rain showers in far southeastern
Wisconsin will improve rapidly to MVFR or even VFR as showers
end tonight. However, IFR ceilings are expected to build back
in overnight. Pockets of fog may develop in low lying areas,
but visibilities will remain in the MVFR category. Northeasterly
winds will continue around 10 kt overnight, with gusts up to 20
kt near Lake Michigan. Sunday, expect ceilings and fog to lift
around midday, with northeasterly winds gusting to 20 kt. VFR
conditions are expected from the afternoon onward, with clearing
skies into the late evening hours.

MH

&&

.MARINE...
Issued 200 PM CDT Sat Aug 1 2026

Open Waters / Synopsis:

Low pressure around 29.6 inches over central Illinois will
slowly progress eastward into tonight, with a continued
northeast breeze across Lake Michigan. Expecting 20-30 kt gusts
over the southern half of the lake. The low will gradually move
east through the Ohio Valley through Sunday night, turning
winds to northerly and bringing additional 20-30 kt wind gusts
to the southern two thirds of the lake. Isolated gales will be
possible Sunday afternoon. Winds will gradually diminish through
Sunday night. High pressure around 30.0 inches then builds into
the eastern Great Lakes Monday, lingering through Tuesday
night. Winds remain light and variable through this time.

Nearshore Zones from Sheboygan through Winthrop Harbor:

A Small Craft Advisory remains in effect through late Sunday
night for all nearshore zones. Northeast winds with 20-30 kt
gusts and waves of 4 to 8 feet (highest further south) will
continue into tonight. A slight decrease in the winds may occur
late tonight, followed by equally gusty north-northeast winds
into Sunday. A few gusts to gale force cannot be completely
ruled out Sunday afternoon.

Sheppard

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072
     until 1 AM Monday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 1 AM
     Monday.

&&

$$

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