Waukesha, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

393
FXUS63 KMKX 071427
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
927 AM CDT Sat Jun 7 2025

.KEY MESSAGES...

- Small shower chances (10-15%) return this afternoon and
  evening.

- Better chances (60-90%) for rain and storms with the passage
  of a cold front for storms Sunday into Monday. Some storms may
  be strong Sunday and Monday.

- Temperatures will remain within a few degrees of normal
  through early next week.

&&

.UPDATE...
Issued 925 AM CDT Sat Jun 7 2025

Some weak echoes of reflectivity south of the La Crosse WI Radar
are evident, likely creating some virga in southwestern WI
through this morning, beneath the broken altocumulus clouds
overspreading the region. Though 5-15% chances for showers
remain in the forecast this afternoon and evening, the
stabilizing influence of easterly / southeasterly winds off of
Lake Michigan and an extremely deep (and plenty dry) mixed layer
are expected to keep showers / weak storms away for today.
Looks like pleasant weather with highs in the 70s inland, 60s by
the shoreline.

06z Model runs for Sunday`s cold front still remain dispersed /
incongruent on the arrival timing, hence will need to wait for
this morning`s 12z guidance before providing an update on the
marginal potential for strong storms.

Sheppard

&&

.SHORT TERM...
Issued 358 AM CDT Sat Jun 7 2025

Today through Sunday night:

Zonal flow remains at 500mb across the central and eastern
CONUS. Under this zonal flow there are multiple shortwaves and
little wiggles moving through, which will again create
sporadic/nebulous upper level lift today. There is one
shortwave trough in particular thats a bit more organized and
stronger than the rest that should pass just to the south of the
state line this afternoon/evening. With sfc high pressure off
to the northeast, dry air at the surface will remain through
much of the morning keeping conditions dry. Any radar returns
are likely to be virga with the stronger showers maybe
producing some drizzle across mainly central and west central
Wisconsin (where there is more low and mid level moisture). As
the surface high pressure begins to move east into the New
England states later today, there will be a slight increase in
moisture especially for areas along the WI/IL border. Increased
moisture and upper level lift has lead to some low chance POPs
around 20% this afternoon and evening. Any rain that makes it to
the ground is likely (80%) to be drizzle/light rain. The best
chance for any rainfall is likely to remain to our south where
the better upper level support (shortwave) will reside.

As the high pressure moves out, low pressure in Manitoba will
deepen and begin to occlude. As this low pressure system slowly
moves eastward, an associated cold front is expected to move
through the Great Lakes Region. There are still little
differences in timing as this cold front phases with/interacts
with the same shortwave that is expected to bring light rain
today. By and large tho, rain is expected (60 to 80% chance) to
move in from the west Sunday afternoon and exit to the east
Sunday evening.

Given the slight differences due to the two phases systems, an
upper level trough and associated sfc cold front with a
shortwave trough to the south of the state. There are two
potential scenarios which will impact the strength and coverage
of any thunderstorms. The earlier and quicker the front moves
through the weaker the CAPE is and we maybe get an isolated
stronger storm. The slower and therefore later the cold front
moves through the better primed the environment will become and
the greater the CAPE will be. This could lead to a few more
marginally severe storms.

With the current set up the models with the slower cold front
movement are the ones that do not have the upper level trough
and shortwave phasing. This difference is on the order of a
couple hours and because of that opted for a middle ground for
POPs since not matter what there is high confidence for rain and
thunderstorms. The main concerns for any stronger storms will be
some brief gusty winds and hail.

Patterson

&&

.LONG TERM...
Issued 358 AM CDT Sat Jun 7 2025

Monday through Friday:

The main upper low is anticipated to swing through the area on
Monday, bringing another round of showers and storms to southern
Wisconsin. Though it will be a bit drier overall on Monday than
Sunday, colder temps aloft and steeper mid-level lapse rates will
lead to some moderate instability. There should be plenty of
forcing with this wave as well, so higher end precip chances
(50-80%) still look warranted. This is supported by 90%+
probabilities for 24 hour measurable precip in the latest ECMWF
and GFS ensembles. Could see a stronger storm or two, with gusty
winds and small hail possible. Temps will likely be a few degrees
below normal Monday given the cooler airmass and expected
clouds/precip.

Mainly dry weather is expected for Tuesday and Wednesday as high
pressure builds into the area. Not out of the question for
isolated showers and maybe a storm on Tuesday as a weak waves
pushes through, but most places will likely be dry. Temperatures
will recover into mid-week as upper level ridging builds in from
the west, with highs up to around 80 by Wednesday.

Could see a few showers/storms Thursday over the top of the ridge,
but confidence in this activity is on the lower end at this
point. Shower and storm chances will then increase late week as
shortwave lifts through the area. Warm temps and increasing
moisture are expected through the end of the week as well.

DDV

&&

.AVIATION...
Issued 925 AM CDT Sat Jun 7 2025

Broken altocumulus clouds will create periods of VFR ceilings
over 8,000 ft today, with some additional thin cirrostratus
around 25,000 ft at times. Inland areas may observe diurnal
cumulus between 4,000 and 7,000 ft (still VFR) this afternoon.
Some virga in southwestern WI with the altocumulus this
morning, then just a 5-15% chance for a shower in the region
this afternoon / evening (most likely for showers /
weak thunderstorms to remain confined to Illinois today given
our lack of instability and dry mixed layer in Wisconsin). Light
east to southeast winds.

A cold front is expected to move eastward across the region
Sunday, with south to southwest winds ahead of the front and due
west or northwest winds behind it. Numerous showers and
thunderstorms expected along the front. Models remain uncertain
on the arrival time and propagation speed of the front, hence
our forecast calls for a wide window (10am-7pm) for the storm
potential, though the progressive nature of the front ought to
limit storm activity / coverage to just a 1-3 hour timeframe
within said window (for any given airport). A strong storm or
two cannot be ruled out.

Sheppard

&&

.MARINE...
Issued 358 AM CDT Sat Jun 7 2025

High pressure over Lake Superior this morning will move east out
of the Great Lakes Region this weekend. As this high moves east,
an area of low pressure will approach the state from the
Northern Plains. Light and variable winds are expected until the
high pressure has moved into the New England States. Winds will
shift to southwesterly Sunday morning and increase, leading to
some moderately breezy winds. Winds will stay well below Gale
Force. Showers and storms are expected Sunday and Monday.
Southwest winds will remain through mid to late Monday then
become westerly.

Patterson

&&

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

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSMilwaukee
www.twitter.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee