647
FXUS63 KMKX 132006
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
306 PM CDT Wed Aug 13 2025

.KEY MESSAGES...

- River flood Warnings remain in effect along portions of
  several Milwaukee metro area rivers and adjacent tributaries.
  Stay away from flood waters and continue to heed any remaining
  road closures in these areas.

- Heat and humidity briefly return to the region late this week,
  building Friday and peaking Saturday.

- Rain and thunderstorm chances return to the forecast this
  weekend into early next week.

&&

.SHORT TERM...
Issued 305 PM CDT Wed Aug 13 2025

Tonight through Thursday night:

Conditions remain calm and quiet through the short term period.
Diurnal cumulus clouds erode rapidly after the sun sets this
evening, with mostly clear skies overnight and nearly calm wind.
This will set the stage for some patchy ground fog / valley fog
to develop late overnight through early Thursday morning,
burning off shortly after sunrise. Simultaneously with the fog,
a plume of wildfire smoke is expected to sag southward over Lake
Michigan, mixing into lakeshore areas in the early morning and
drifting / dispersing westward with the lake breeze flow later
Thursday morning. HRRR and RAP near surface smoke output then
allows the smoke to mix out into the afternoon.

Sheppard

&&

.LONG TERM...
Issued 305 PM CDT Wed Aug 13 2025

Friday through Wednesday:

Upper level ridging makes steady progress over the midwest region on
Friday, allowing quiet weather to continue and for daytime high
temperatures to climb into the mid to upper 80s. Surface winds
turn due south at around 10 MPH, gradually drawing up the warmer
and more humid airmass.

Southerly WAA continues at the surface into Saturday, likely driving
dewpoints back into the 70s. The upper level ridge axis develops a
negative tilt and amplifies into this weekend, with the southern
(subtropical) jet remaining nearby to our north (over Lake
Superior). The right entrance of said jet streak passes just
north of us, leading to some upper air divergence, with 500mb
shortwave troughs passing by in some model guidance. For
Northern Wisconsin (including Green Bay, closer to the jet
dynamics aloft), 50-60% chances for showers and thunderstorms
are forecast on Saturday. For our CWA Saturday morning and early
afternoon, this manifests as a 15-45% chance, with the highest
probabilities further north towards Sheboygan and Berlin, and
the lowest chances towards the WI/IL border. Later Saturday (and
as always, this timing may change) we would expect this
thunderstorm activity to sag southward / southeastward into our
region (following the Corfidi vectors), towards the higher
convective instability and PWATs of 1.75 to 2.00 inches. With
relatively slow corfidi vectors, high PWAT, and moderate to high
instability, the threat for heavy rainfall would once again be
present somewhere in our region, though exactly where this lands
in Wisconsin is challenging to predict from this far out in
time. Needless to say, we will be monitoring this very closely,
given that some area rivers are progged to remain at elevated
levels through this week due to last weekend`s heavy rainfall
event. In the event Saturday`s precip potential holds off until
the evening or later, daytime high temps could easily approach
90 degrees Saturday afternoon, allowing heat indices to approach
triple digit territory.

Into early next week, the right entrance to the subtropical jet
streak remains nearby, corfidi vectors remain slow, and PWAT /
CAPE has the potential to remain similarly high. So, the
ingredients for a localized heavy rainfall event somewhere in
the region remain in place into early next week (Saturday,
Sunday, Monday, possibly Tuesday). I use the word "somewhere" in
the aforementioned setup, given that the general expectation is
for thunderstorms to evolve off the upper air perturbations,
forming a pseudo cold front that sags south and stalls (becoming
a stationary front) that could become the focal point for
showers and thunderstorms with heavy rainfall. Exactly where
this boundary sets up is not yet known. To be completely honest,
it may not be until it does form that we know where it will
stall. Ensemble Max Temperature plume diagrams reveal that on
any given day through this stretch, if we have a dry morning /
early afternoon period, temperatures could soar to the upper 80s
or around 90. In the event of more active morning / afternoon
weather, clouds would hold temperatures to the low 80s or upper
70s.

Towards the middle of next week (perhaps Tuesday or Wednesday) we
would likely see the end of said "ingredients" for heavy rainfall as
we find ourselves on the west side of an upper trough, with surface
high pressure likely becoming dominant, along with drier
weather.

Sheppard

&&

.AVIATION...
Issued 305 PM CDT Wed Aug 13 2025

Scattered diurnal cumulus clouds around 5,000 ft above ground
will erode rapidly as the sun sets this evening, along with the
east to northeasterly lake breeze. Mostly clear skies and nearly
calm winds expected tonight, with some potential for patchy
ground fog and valley fog for inland areas late tonight into
early Thursday morning, eroding shortly after sunrise. For
Thursday, continued dry weather and VFR, with a light south to
southeasterly breeze. A due-east lake breeze will also evolve in
the early afternoon.

Sheppard

&&

.MARINE...
Issued 305 PM CDT Wed Aug 13 2025

High pressure of 30.2 inches will remain dominant over Ontario
Canada Tonight through Thursday, resulting in light and variable
winds over the lake. High pressure drifts further east across
Canada later this week as a surface pressure trough deepens over
the Rockies and High Plains. This will allow 10 to 20 knot
southerly winds to develop Friday. Chances for showers and
thunderstorms return Saturday through the first half of next week
as a cold front slowly sags southward across the lake and stalls
somewhere nearby.

Sheppard

&&

.HYDROLOGY...
Issued 305 PM CDT Wed Aug 13 2025

Flood Warnings remain in effect along several Milwaukee metro area
rivers and their adjacent tributaries in the wake of the heavy
rainfall this past weekend. The Fox River in Waukesha has dropped
from moderate to minor flood stage, and is expected to continue to
slowly decrease to below flood stage going into Friday morning.
The Menominee River at Menominee Falls has begun to fall slowly
toward the edge of minor flow stage, and is expected to continue
to fall. The Milwaukee River and Cedar Creek at Cedarburg have
also begun a downward trend and are expected to continue to fall
through Friday.

The Rock River at Lebanon continues to slowly rise, expected to
reach minor flood stage later today, and therefore a Flood Warning
has been issued.

The Fox River at New Muster is forecast to reach minor flood stage
Thursday night, and is being monitored with a River Flood Watch.

Ponding of water in areas immediately near each river segment
will remain possible until each can fall below flood stage by
later this week. Continue to heed any road closures in all
impacted areas until river stages recede further and Flood
Warnings are allowed to expire.

MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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