Waukesha, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

274
FXUS63 KMKX 290840
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
340 AM CDT Sun Jun 29 2025

.KEY MESSAGES...

- Heat index vales in the middle to upper 90s are expected this
  afternoon.

- Scattered thunderstorms are forecast this afternoon and
  evening, along and ahead of a cold front. Gusty winds are
  possible with the strongest storms.

- Scattered thunderstorms are possible Monday, as the cold front
  moves through the area. Gusty winds and small hail are
  possible with the strongest storms.

- Chances for showers and thunderstorms returns later in the
  week, along with warmer and more humid conditions.

&&

.SHORT TERM...
Issued 340 AM CDT Sun Jun 29 2025

Today through Monday:

The current convection in west central to north central
Wisconsin should remain north of the area into this morning,
where the low level jet is pointed into and transporting
moisture and upward vertical motion. A few stray showers or a
storm may develop into this morning in the northern or
northwestern parts of the area, closer to the low level jet
axis, but should be short lived and weak. Added some 20 percent
PoPs in these areas just in case.

Any lingering cirrus from the current convection should
gradually dissipate this morning, with diurnal cumulus
developing by this afternoon.

Very warm and humid conditions are expected this afternoon,
with highs reaching the around 90 degrees or into the lower 90s.
Dewpoints around 70 degrees should bring heat index values into
the middle to upper 90s across the area. No Heat Advisory is
needed, as the forecast has been consistent for middle to upper
90s heat index values, which are in the 90th to 95th percentile
of the NBM distribution. There should be a southeast lake breeze
this afternoon that may cool down areas close to Lake Michigan.

CAMs are now generally developing scattered convection along a
weak cold front/pre-frontal trough by middle to late afternoon
from north central Wisconsin to the La Crosse area and into
northern Iowa. Several prior runs of the CAMs were showing this
development over the forecast area, so this is a shift back to
the west.

They bring this scattered activity east into south central
Wisconsin by early this evening, and through the rest of the
area by middle to late evening, gradually weakening. There is
some capping to overcome in the afternoon, but should weaken by
00Z Monday.

Forecast soundings are showing 2000 J/kg or greater mean layer
CAPE in south central Wisconsin, though deep layer bulk shear
remains weak in the 15 to 20 knot range. Could still get gusty
winds or even an isolated severe wind gust with the strongest
storms in south central Wisconsin into early evening, before
weakening as they shift east. Given the scattered nature of the
convection, left PoPs in the 40 to 60 percent range, highest in
western parts of the area. There may be a lull in the activity
overnight and early Monday morning.

CAMs are now showing another round of scattered showers and
storms developing with the main cold front either just west of
the area or over parts of south central Wisconsin from middle
morning to midday, then shifting east through the area in the
afternoon. There may be a trailing line of showers and storms
later in the afternoon with the approach of the 500 mb shortwave
trough and upper divergence. Forecast soundings are showing
enough mean layer CAPE and better deep layer bulk shear of 30 to
40 knots to bring a risk for gusty winds and small hail with the
strongest storms. Highs should reach the lower to perhaps middle
80s Monday, with west winds limiting the lake breeze potential.

Wood

&&

.LONG TERM...
Issued 340 AM CDT Sun Jun 29 2025

Monday night through Saturday:

The cold front and upper trough will finally pass by Mon
evening with wnwly winds and weak cold advection into Tue. A
flat sfc ridge will follow for Wed with perhaps a brief period
of warm, moist advection bringing 20-30 percent chances for
showers and storms mainly Wed nt. High temps in the lower to
middle 80s are expected during this time with lower dewpoints in
the lower to middle 60s.

A sfc ridge will return for Thu followed by a building upper
ridge over the center of the USA. At the surface, low pressure
will track from the lee of the central Rockies toward Lake
Superior. Breezy sly winds and warm, moist advection will
prevail to the east of the low and underneath the ridge bringing
a return of very warm temps and heat indices in the 90s for
Fri-Sat. The upper ridge will be flattened over the Great Lakes
as a well organized low tracks from Ontario to Quebec. Its cold
front will sag south into srn WI on Sat with 40-60 percent
chances for showers and storms.

Gehring

&&

.AVIATION...
Issued 340 AM CDT Sun Jun 29 2025

The current showers and storms in west central to north central
Wisconsin should remain north of the area into this morning. A
few stray showers or a storm may develop into this morning in
the northern or northwestern parts of the area, but should be
short lived and weak. Any lingering cirrus should gradually
dissipate this morning, with scattered to broken diurnal
cumulus developing by this afternoon.

South to southwest winds are expected today, and there should
be a southeast lake breeze this afternoon for the terminals
closer to Lake Michigan. Winds will become light tonight.

Scattered showers and storms may push east into Madison and
Janesville terminals by early this evening, and through the
rest of the area by middle to late evening, gradually weakening.
For now, will continue to use PROB30 groups for this potential
in TAFs. May see gusty winds with the strongest storms, as well
as 2 to 4 mile visibility.

Another round of scattered showers and storms may develop over
or just west of the area Monday morning and shift east through
the area in the afternoon, with the main cold front. There may
be a trailing line of showers and storms later in the afternoon
as well. Gusty winds and small hail may occur with the strongest
storms. West to northwest winds are expected on Monday.

Wood

&&

.MARINE...
Issued 340 AM CDT Sun Jun 29 2025

South to southeast winds will increase today, becoming south to
southwest tonight, as weak high pressure around 30.0 inches
moves east of the region. A weak cold front will approach the
region from the Upper Mississippi River Valley later today and
tonight, moving across the region Monday. Southwest winds will
become west behind the front later Monday into Monday night.
Showers and some thunderstorms may accompany the frontal
passage, with gusty winds possible with any stronger storms.
West winds should generally linger into the middle of the week.

Wood

&&

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

$$

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