575
FXUS63 KMKX 290834
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
334 AM CDT Fri Aug 29 2025

.KEY MESSAGES...

- Beach Hazards Statement continues through 7 AM this morning at
  all Lake Michigan beaches.

- Slight chances (~15-25%) for a few scattered showers and thundershowers
  this afternoon & evening.

- Dry conditions with a gradual warming trend this weekend into early
  next week.

- Next shower and thunderstorm chances (~40-60%) return to the
  forecast Wednesday into Thursday.

&&

.SHORT TERM...
Issued 337 AM CDT Fri Aug 29 2025

Today through Saturday:

Synopsis/Mesoanalysis: A broad area of surface high pressure extends
from Lake Superior toward the Bay of Green Bay early this morning,
resulting in light and variable surface winds across southern
Wisconsin. Nighttime microphysics imagery shows low clouds near the
Lake Michigan shoreline, where light east-northeast winds have
pulled marine air inland. Fog is beginning to fill in over the
Wisconsin River Valley, with more isolated pockets of ground fog
having been reported in low-lying spots along the Kettle Moraine and
over far south-central Wisconsin. The lake effect clouds and
valley/ground fog will linger through daybreak, with both beginning
to mix out after sun comes up this morning. Currently extending from
the Twin Cities north to the Ontario-Manitoba border, a 500 mb
shortwave & weak area of upper divergence will move into southern
Wisconsin this afternoon/evening, providing enough lift for a few
scattered showers and thundershowers. Precip chances will wane late
tonight as the responsible forcing mechanisms shift south of the
area. Dry conditions will continue through the day on Saturday as
temps climb into the low-mid 70s areawide.

Rest Of Overnight: Will be monitoring the progress of valley fog in
the Wisconsin Valley, in addition to any areas of ground fog along
the Kettle Moraine and in far south-central Wisconsin, through
daybreak. Don`t anticipate widespread dense fog, but will be
monitoring Wisconsin Valley obs for pockets of < 1 mile
visibilities. Expect any areas of fog to dissipate quickly after
sunrise. Budget a few extra minutes of travel time if taking to the
roads early this morning in the Wisconsin Valley. Elevated waves
will continue at all Lake Michigan beaches through daybreak, with a
Beach Hazards Statement in effect through 7 AM. Exercise extreme
caution if heading lakeside through sunrise.

Today through Tonight: Have maintained slight chance (~15-25%)
precip probabilities primarily along/west of I-41, where a pair of
mid-upper forcing mechanisms will cross during the afternoon and
evening time frame. A few rumbles of thunder could mix in with
precip during the afternoon/early evening, particularly to the west
of Madison where forecast soundings show some instability. Apart
from a few flashes of lightning, hazards are not anticipated in any
showers/thundershowers. Areas of fog will be possible after
midnight, with some locally dense fog possible along/west of
I-39.

Quigley

&&

.LONG TERM...
Issued 337 AM CDT Fri Aug 29 2025

Saturday night through Thursday:

500 mb flow becomes weaker Saturday night into Monday, with a 500 mb
low developing over eastern South Dakota and Nebraska Saturday night
into Sunday night, shifting into western Iowa. This becomes more of
an open wave on Monday and shifts to the southeast of there. An
associated surface low develops beneath the upper low, with most of
the precipitation remaining to the west of the area.
High pressure to the east of the region helps keep easterly flow in
the low levels and helps with keeping the precipitation to the west.
For now, will maintain a dry forecast Saturday night into Monday,
with temperatures moderating closer to seasonal normal values.

There is more consensus from the 500 mb cluster analysis of the EPS,
GEFS and Canadian ensembles with a rather amplified 500 mb longwave
trough developing over the Great Lakes region Tuesday into Wednesday
and deepening into the rest of next week. This may allow for a
fairly strong cold frontal passage on Wednesday, with perhaps
showers at times within the cyclonic flow into the rest of the week.
This would also support cooler temperatures for later in the week,
which is somewhat reflected by the NBM and ensemble trends. For now,
will keep NBM PoPs in the 20 to 40 percent range for Tuesday night
into Wednesday night, and may need more shower chances later in the
week.

Wood

&&

.AVIATION...
Issued 337 AM CDT Fri Aug 29 2025

VFR conditions prevail early this morning at terminals away from
Lake Michigan, with impacts from lake effect clouds ongoing at ENW,
MKE and SBM. Cloud deck has varied between SCT and BKN coverage
since midnight, with bases generally in the FL025 and FL035 range.
Have accounted for this variance near-term with TEMPO groups at ENW,
MKE and SBM, with the expectation for prevailing MVFR to become
established following 09Z at all fields. Generally expect clouds to
lift out by mid-morning, allowing for a return of prevailing VFR at
all terminals. Whether or not lake effect clouds will make it far
enough inland to UES remains uncertain, with trends being monitored
for possible impacts through sunrise. Have also inserted TEMPO BR
mentions at JVL through daybreak, where patchy ground FG is
possible. Scattered -SHRA and -TSRA are forecast this afternoon
primarily west of Interstate 39. Have withheld any mentions in the
06/09Z updates at MSN and JVL, but will be monitoring trends into
this afternoon. FG is possible late tonight, particularly across
western portions of the area. May consider introducing mentions in
the JVL and MSN 12Z updates depending on model guidance trends.

Quigley

&&

.MARINE...
Issued 337 AM CDT Fri Aug 29 2025

1022 mb high pressure is centered over Lake Superior early this
morning, resulting in east-northeast winds across the open waters of
Lake Michigan. The high will settle over the Lake Michigan vicinity
this morning, resulting in decreasing northeasterly wind speeds.
Winds will become light and variable tonight through Saturday as the
area of high pressure drifts into Lower Michigan. The high will
gradually break down Sunday into early next week, though light and
variable winds will persist in the absence of any organized areas of
low pressure over the western Great Lakes and northern Great Plains.
Prevailing south to southwest winds will become established Tuesday
and Tuesday night as 1012 mb low pressure approaches Lake Michigan
from Ontario. Said low is forecast to drag a strong cold front
across the waters at some point Wednesday through Wednesday night,
bringing a gusty northwest wind shift to all of Lake Michigan. Gusty
northwest winds will continue through most of Thursday. While the
current forecast keeps gusts below gale force next Wednesday-
Thursday across the open waters, the potential for increasing trends
will be monitored as this portion of the period draws closer.
Showers and thunderstorms will accompany the passing cold front
Wednesday into Thursday, with details regarding possible strong
thunderstorm wind gusts or waterspouts unclear at this time. Will
continue to monitor trends over the coming forecasts.

Breezy northeast winds continue in nearshore zones through sunrise,
with a Small Craft Advisory remaining in effect until 7 AM CDT from
Sheboygan south to Winthrop Harbor. Currently anticipate that the
advisory will be able to expire as scheduled with high pressure
settling over Lake Michigan this morning, but will nevertheless
monitor gust and wave trends through daybreak. Light and variable
winds are forecast tonight through early next week as high pressure
lingers over Lower Michigan. A cold front will cross Lake Michigan
during the Wednesday to Wednesday night time frame, bringing a gusty
northwest wind shift to all nearshore zones by early Thursday
morning. Showers and storms will accompany the passing front. While
the current forecast keeps winds and waves just below Small Craft
Advisory thresholds, the potential for increasing trends will be
monitored over the coming forecasts.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072
     until 7 AM Friday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 AM
     Friday.

&&

$$

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