Waukesha, Wisconsin Weather Forecast Discussion

436
FXUS63 KMKX 051450 AAA
AFDMKX
Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
950 AM CDT Sun Oct 5 2025
.KEY MESSAGES...
- One more day of summer-like temps in the lower to middle 80s
  today, with gusty southerly winds up to 30 MPH.
- Dry conditions are expected through this evening, but chances
  for showers and thunderstorms (40 to 80 percent) return later
  tonight into Monday with a slow-moving cold frontal passage.
- A Small Craft Advisory is in effect today into tonight for
  gusty south winds and building waves along Lake Michigan.
- Cooler, more seasonal and closer to normal temperatures
  return for mid-week.
&&
.UPDATE...
Issued 950 AM CDT Sun Oct 5 2025
South winds will continue to increase today, becoming gusty as
the pressure gradient tightens and low level mixing increases.
Gusts up to 30 MPH are expected at times this afternoon. High
temperatures still look to reach the lower to middle 80s this
afternoon. Areas along the lakeshore may see temperatures cool a
bit if the south winds turn more south southeast.
Models continue to bring the cold front southeast toward the
northwest parts of the area later tonight and through the area
on Monday, shifting southeast Monday night. Still anticipate
showers and a few storms gradually weakening as they shift
southeast into northwest parts of the area later tonight into
Monday morning.
A lull in the activity is then expected, before more showers
and a few storms develop in southeast parts of the area Monday
afternoon and shift southeast during the evening. There is not
much upward vertical motion besides the low level frontogenesis
response and perhaps some upper divergence. Forecast soundings
are showing just enough moisture, and instability is weak in the
southeast parts of the area Monday afternoon. Think the current
forecast is on track for the most part. Temperatures will
remain warm ahead of the front Monday, with 70s to lower 80s,
with cooler 60s behind it.
Wood
&&
.SHORT TERM...
Issued 408 AM CDT Sun Oct 5 2025
Today through Monday:
Will be another day of summer-like temps across southern WI
today with high temps a few degrees cooler but still expected to
top of in the low to mid 80s this afternoon. Given the tighter
pressure gradient building ahead of the deepening low lifting
from the east side of the Dakotas into Ontario today, expect
gusty conditions through the day across southern WI. Will see
gusts of 20-30 mph through the afternoon and evening before
gradually easing overnight into Monday ahead of an approaching
cold front.
Additionally will see shower chances increase late tonight
through the day Monday ahead and along a slow moving cold front.
While a welcoming change in the pattern, rainfall amounts are
trending on the lower side, generally below half an inch across
much of the area. Main reason for the lack luster rainfall will
be because much of the upper-level support remains to the north
of the area closer to the center of the mid-level trough and
associated upper-level dynamics. Also timing will play a role as
the 00z-06z CAMs prog a broken line of shower and storms to
decay/weaken as it moves into southern WI overnight into early
Monday morning. Models then suggest either lingering light
showers or even a lull in activity mid-Monday morning/early
afternoon as the cold front slides through the area. Then could
see the line of shower/storms reinvigorate later Monday
afternoon/early evening across southeastern WI where daytime
heating helps build a bit of instability (MUCAPE between 400-750
J/kg) back into the southeastern part of WI. So while not
expecting much in the way of widespread heavy rain or any
stronger storms, cannot rule out a localized pocket of moderate
to heavy rainfall bringing slight higher rainfall amounts above
half an inch. Otherwise, post cold front will bring northerly
winds and a drier, cooler airmass to southern WI through Monday
night.
Wagner
&&
.LONG TERM...
Issued 408 AM CDT Sun Oct 5 2025
Monday night through Saturday:
Surface high pressure builds into the central Great Plains
Monday night, helping to slowly push the cold front out of our
region, with shower chances decreasing in a NW to SE manner into
early Tuesday morning. Light north to northwest winds linger
into Tuesday, with decreasing cloud cover and highs in the mid
60s (around or just a touch above seasonal norms). High pressure
deepens over southern Ontario and the Great Lakes region
through Wednesday, allowing dry weather to continue under sunny
skies. A slight warming trend ensues for the latter half of the
week as the aforementioned high pressure tracks eastward across
the northeastern CONUS states and into the Atlantic Ocean. Light
east winds on Wednesday veer south on Thursday and boost
temperatures towards the 70 degree mark.
Though dry weather is likely through much of the latter half of
the week, a weak cold front similar to what we are dealing with
early in the week may cross the region, with some accompanying
500mb perturbations. As such, there will be periods of 10-25%
rain chances.
Sheppard
&&
.AVIATION...
Issued 950 AM CDT Sun Oct 5 2025
South winds will continue to increase today, becoming gusty as
low level mixing increases. Gusts up to 25 to 28 knots are
expected at times this afternoon. The south winds may turn more
south southeast along the Lake Michigan shore, though south
winds should linger at Sheboygan, Milwaukee and Kenosha.
South winds will linger this evening ahead of the approaching
cold front, with low level wind shear conditions expected with
2000 foot AGL winds from the south southwest around 40 knots.
Winds will weaken and shift northwest to north Monday, as the
front moves southeast through the area.
Showers and a few storms should gradually weaken as they shift
southeast into northwest parts of the area later tonight into
Monday morning. A lull in the activity is then expected,
before more showers and a few storms develop in southeast parts
of the area Monday afternoon and shift southeast during the
evening. May see locally reduced visibility values with any
showers and storms. A period of ceilings of 1000 to 2000 feet
AGL should occur Monday with the frontal passage.
Wood
&&
.MARINE...
Issued 950 AM CDT Sun Oct 5 2025
Increasing southerly winds are expected across Lake Michigan
today, as strengthening low pressure around 29.3 inches tracks
from the eastern Dakotas into Ontario. The strongest winds will
be across the northern third of the open waters, where gale
force gusts are expected tonight. A Gale Warning is in effect
for this area.
Otherwise, the southern two-thirds of the lake will see
southerly gusts up to 30 knots today into tonight. A Small Craft
Advisory is in effect for the nearshore waters of Lake Michigan
today into tonight, for gusty south winds and building waves.
Winds are expected to shift to the southwest and gradually
weaken into Monday morning, ahead of an approaching cold front.
A northerly wind shift is expected through the day Monday behind
the cold front, and is progged to push south of Lake Michigan by
Monday night. High pressure around 30.4 inches looks to quickly
build in behind the cold front for Tuesday into Wednesday.
Wagner/Wood
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning...LMZ261-LMZ362-LMZ364-LMZ563...5 PM Sunday to 2
     AM Monday.
Small Craft Advisory...LMZ643 until 7 AM Monday.
Small Craft Advisory...LMZ644-LMZ645-LMZ646 until 1 AM Monday.
&&
$$
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NWS MKX Office Area Forecast Discussion