New Berlin, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

440
FXUS63 KMKX 251953
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
253 PM CDT Fri Jul 25 2025

.KEY MESSAGES...

- Isolated to scattered thunderstorms (20-30%) this evening
  along the WI/IL border. Better chances (30-60%) late tonight
  and Saturday, especially for areas south of HWY-151.

- Hot and very humid Sunday and Monday with upper 90s to triple
  digits heat indices.

- Periodic shower/storm chances through later Sunday and into
  early next week before an eventual cold front passage midweek.

&&

.SHORT TERM...
Issued 253 PM CDT Fri Jul 25 2025

Tonight through Saturday night:

High pressure remains centered over the upper Great Lakes with
the stalled frontal boundary set up south across IL/IN. This
afternoon is still fairly warm with not much relief in dewpoints
(upper 60s- low 70s) even with easterly winds off of the lake.
The high will gradually slide east this evening/tonight with
overnight lows in the mid to upper 60s before southerly flow
gradually builds back into southern WI and will see the stalled
boundary lift back northward as well. Could see a few showers
and storms later this evening as the elevated humidity level
paired with a lifting warm frontal boundary and MCV (currently
centered across southern IA) may trigger development across far
southern WI. However model trends are leaning more in favor of
the late evening activity either hugging the WI/IL border or
staying south where the front lingers a bit longer with the
sub-30 kt LLJ.

Expecting more widespread shower and storm activity to develop
into Saturday morning as another MCS/MCV, currently centered
over NE/KS border, lifts northeastward into the region. With the
return of higher moisture and PWATs creeping back above 1.5 to
around 2 inches, expecting increased shower chances through
Saturday morning as a mid-level shortwave trough lifts in from
the southwest across WI/IL. Latest model trends continue to
favor the southern half of the CWA (along and south of I-94) to
see much of this activity, but could see it as far north as
HWY-151, with areas northwest remaining mostly dry. However
given the uncertain nature of an MCS, could see things shift
depending on where the features ends up tracking. Given the
increasing moisture, will see instability climb with the 12z
HREF progging at least 500-1000J/kg of MUCAPE accompanying the
incoming MCS. Thus few embedded thunderstorms will be possible
Saturday morning into the early afternoon. Any delay in the
timing of the MCS and morning shower activity will help
instability climb upward and increase the thunderstorm
potential into the afternoon. If this scenario ends up panning
out, then cannot rule out seeing a storm or two grow tall enough
and produce gusty winds and even some small hail. However,
continue to see the better potential for stronger storm further
south into IL where the greater instability and deep layer shear
will be in associated ahead of the MCS.

Much of the shower and storm activity does look to be through
the area by the later half of the afternoon. While looking at a
drier evening, not expecting much of a change in airmass so the
humidity will linger into Saturday night with lows in the upper
60s to low 70s.

Wagner

&&

.LONG TERM...
Issued 253 PM CDT Fri Jul 25 2025

Sunday through Friday:

Upper-level high pressure remains established over southeastern
CONUS into early next week. This will place southern WI at the
top of the upper ridge with southwesterly flow advecting in a
more tropic airmass into southern WI Sunday through the start of
next week. Given this pattern, it lends way to another hot and
humid stretch with temps in the upper 80s into the 90s and even
hotter heat indices ranging from the mid-90s into triple digits,
especially for Monday and may even see the heat continue into
Tuesday. Thus heat headlines may be needed early next week.
However, there continues to be uncertainty with temps as periods
of showers/storms from upper-level waves overrunning the ridge
and bringing an MCS or two across the region may present a
wrinkle in the forecast limiting the heat potential. Difficult
to pinpoint the cloud cover and shower/storm chances from a wave
or two this far out, but mid-range models hint a few
opportunities one being Sunday night into Monday and again on
Monday night into Tuesday. Nevertheless will be the potential
for wave of showers/storms to accompany the hot and humid
stretch into early next week.

Upper-level high gradually meanders back westward midweek and
will allow for the upper-level trough to work its way across the
Upper Midwest. With the ridge to the west, northwesterly flow
and cooler pattern then looks to set up across the Great Lakes
for the second half of next week. Long-range models also show
(fairly consistently) a surface high pressure set up over the
region through the end of the week, which would support near-
normal if not slightly below normal temps.

Wagner

&&

.AVIATION...
Issued 253 PM CDT Fri Jul 25 2025

Some lingering low clouds with pockets of MVFR ceilings along
the lakeshore (KMKE and KENW) and across south-central WI
(KJVL), but continue to see ceilings improve and scatter out
this afternoon. Influence from the high pressure over the Upper
Great Lakes will continue through the evening with VFR
conditions and light and variable winds. Will gradually see a
southerly wind shift tonight into Saturday as the frontal
boundary across IL gradually lifts northward into southern WI.
Will be the focus for isolated shower/storm activity overnight,
mainly along the WI/IL border. However, there will be
additional, more scattered and widespread showers with a few
embedded thunderstorms for the first half of the day Saturday,
generally for areas south of line from Port Washington to
Darlington. Will see lower MVFR ceilings (<3kft) move in through
the morning, but accompanying any showers and storms Saturday
will be lower visibility and lower ceilings (<2kft). Shower and
storm chances diminish later Saturday afternoon and evening with
light southerly winds lingering across the area.

Wagner

&&

.MARINE...
Issued 251 PM CDT Fri Jul 25 2025

High pressure centered over Lake Superior and northern Lake
Michigan will gradually slide east tonight. Then a frontal
boundary stalled south of Lake Michigan this afternoon is
expected to gradually lift northward overnight into Saturday.
Will see lighter north and easterly winds north of the boundary,
but will begin to shift more southerly behind it. Light
southerly winds will prevail by Saturday afternoon/evening
across all of Lake Michigan. Will continue to see light to
occasionally moderate southerly winds prevail through the
weekend into early next week. There will be a few windows for
shower and thunderstorms to track across the Lake
tonight/Saturday and again Sunday night into Monday and again
midweek. May see more variable winds accompanying any storm
complex that traverses the Lake through early next week.

Wagner

&&

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

$$

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