West Allis, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

489
FXUS63 KMKX 201531
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1031 AM CDT Sun Jul 20 2025

.KEY MESSAGES...

- Chances for storms develop Tuesday night, and again Wednesday
  night into Thursday. Exact timing and intensity remains in
  question, with the most confidence in seeing widespread
  convection on Thursday.

- Heat builds back into the region, with highs in the lower 90s
  Wednesday and Thursday. Heat index values of 100 to 105
  degrees are possible on Wednesday.

&&

.UPDATE...
Issued 1031 AM CDT Sun Jul 20 2025

Forecast remains on track. A few showers have developed along a
line of convergence in southwestern Wisconsin where winds shift
from northeast to east. These showers are weak and not expected
to produce more than perhaps an isolated bolt of lightning. In
general, expecting any additional showers that develop to pulse
up and decay rapidly. Precipitation chances will continue to
diminish through this afternoon. Expecting cloud cover to also
diminish this afternoon, with high pressure and cooler, drier
air moving in. However, within this area of high pressure,
wildfire smoke will also move in, creating at minimum hazy skies
and perhaps even working down to the surface and leading to
diminishing visibility.

MH

&&

.SHORT TERM...
Issued 306 AM CDT Sun Jul 20 2025

Today through Monday:

The cold front continues to slide WSW through southern WI early
this morning. This is clearly delineated by low clouds on
satellite and light northeast winds on surface observations. All
precip associated with this front diminished. Meanwhile, a weak
shortwave crossing southern WI kick off a few showers or
sprinkles. The clouds will gradually diminish from north to
south, beginning late in the morning. High pressure and dry air
working into the area will give us dewpoints in the 50s by
tonight, and thus lows in the upper 50s to around 60 inland from
southeast WI.

Our shower and storm chances will be largely protected by this high
pressure today through Monday. The easterly winds will keep our
temperatures in check, with highs ranging from the lower 70s
east to upper 70s inland today, and upper 70s to lower 80s
Monday. Expect mostly sunny skies with some diurnal cumulus
clouds.

Cronce

&&

.LONG TERM...
Issued 306 AM CDT Sun Jul 20 2025

Tuesday through Saturday:

High pressure drifts east of the region on Tuesday, allowing
southerly flow to resume and temperatures to climb rapidly (highs
in the mid 80s, with low 80s further east near the lake). As
surface pressure troughing east of the Rockies gradually evolves
into a weak Surface low over central MN / northern WI late
Tuesday, a chance for showers and thunderstorms is forecast to
develop, but with the majority of the activity missing our CWA to
the north (perhaps ~30% chances for our northern tier counties
Tuesday PM).

The aforementioned low pressure exits east, leaving a weak surface
front / pressure trough southwest of it that slowly sags southward
into later this week. This feature, combined with the proximity
of the jet stream to our north leaves the potential for a few vort
maxes to ride the crest of the ridge, yielding occasional chances
for showers and storms through the remainder of the week. The
majority of said chances on Wednesday (~30%) remain confined to
the northern CWA (central / east-central WI) closer to the jet
aloft. Chances peak area-wide on Thursday (40-50%, mainly
afternoon / evening) as the aforementioned surface frontal
boundary drifts closer, then taper down into Friday. Chances and
timing will of course be subject to change, given the low
predictability of the exact pattern.

Heat is expected to peak mid week (especially Wednesday), with
daytime high temps in the low to mid 90s, and dewpoints in the mid
70s (possibly even upper 70s). As such, heat headlines remain a
possibility.

Sheppard

&&

.AVIATION...
Issued 1031 AM CDT Sun Jul 20 2025

Ceilings around 1000-1500 ft are dominant across far southern to
southwestern Wisconsin, but are quickly breaking up and giving
way to VFR conditions going into the afternoon. Clouds will
continue to break up and give way to clear skies into tonight.
However, a batch of wildfire smoke will move in as clouds exit,
bringing potential for hazy skies and perhaps some lowered
visibilities if it can make it to the surface tonight into
Monday.

Generally northeasterly winds continue through tonight, shifting
to become southeasterly into Monday.

MH

&&

.MARINE...
Issued 306 AM CDT Sun Jul 20 2025

Northerly winds in the wake of a cold front will become decrease
today as high pressure of 30.1 inches slides across the Upper
Great Lakes. Winds will shift to the east on Monday as the high
moves into Ontario.

Winds will increase to around 20 knots and become southeast on
Tuesday as low pressure of 29.5 inches approaches from the Central
Plains. There are chances for storms Wednesday through Friday
along a frontal boundary that sets up across the northern part of
Lake Michigan. South to southwest winds will remain elevated
Wednesday and Thursday. A low pressure trough around 29.8 inches
will drop through the area Thursday night into Friday.

Cronce

&&

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

$$

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