NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 090509
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1209 AM CDT Sat May 9 2026

.KEY MESSAGES...

- 15% percent chances for light rain showers today, with breezy
  northwest winds this afternoon.

- Below normal temperatures return for Sunday and Monday with
  additional Frost Advisories possible over portions of srn WI.

- A clipper system brings high rain chances (80 percent) for
  Tuesday. A few thunderstorms will be possible but no severe
  storms are anticipated at this time.

&&

.SHORT TERM...
Issued 1200 AM CDT Sat May 9 2026

Today and Tonight:

Broken altocumulus clouds will linger aloft through the overnight
hours, with plenty of dry air in the Residual Layer beneath and some
virga evident on radar. 850-700mb WAA and loosely organized FGEN may
manage to produce some brief sprinkles of rain out of this activity
through the overnight hours, but precip chances are capped at
~15% or less.

A cold front crosses the region early this morning, with breezy
northwest winds arriving behind it later this morning through this
afternoon. Some 20-30 MPH gusts can be expected, stronger gusts
to ~35 MPH cannot be ruled out. Daytime high temps in the 60s
to around 70 across the region today, with the synoptic breeze
spreading the warmth all the way through the shoreline. An axis
of open cellular light rainshowers may develop in the wake of
the cold front today, aided by some 500mb PVA. But, similar to
the ongoing altocumulus / virga, it's likely to evaporate before
reaching the ground, leaving only ~15% or less rain chances.

Northwest winds decelerate and sky cover decreases tonight, with
some slight potential for frost development towards the northwest
corner of the CWA (towards central WI, low temps in the mid 30s),
likely too warm elsewhere.

Sheppard

&&

.LONG TERM...
Issued 1200 AM CDT Sat May 9 2026

Sunday through Friday:

High temperatures around 60 degrees expected Sunday, with a
redeveloping NW breeze. Some potential for a lake breeze to push
against this synoptic flow and hold shoreline temperatures to the
low/mid 50s, though our current forecast spreads 60 degree highs
right up towards the shoreline. Dry weather looking likely as
high pressure builds in from the northwest. Potential for frost
in inland areas Sunday night, particularly in the northwestern
corner of the CWA towards central WI (lows in the low to mid
30s). Calm winds and clear skies looking likely.

High pressure passes overhead Monday with temperatures holding
steady (around 60) for inland areas. The weak synoptic wind flow
will allow a healthy easterly lake breeze to form, likely holding
shoreline high temps to the low 50s. Dry weather continues.

A clipper system will track eastward across the region on Tuesday,
delivering 80% rain chances. The majority of model QPF falls during
the daytime hours regardless of whether the low tracks through
southern WI (08.12z ECMWF) or lake superior (08.18z GFS), with
precip chances arriving from the west as early as predawn Tuesday
and exiting east as late as Tuesday evening (the precip would only
last a small fraction of that window in any case). There will
be chances for thunderstorms at times (particularly Tuesday
afternoon), but strong to severe storms are not looking likely
given the difficulty of a fast-propagating clipper system
trying to draw sufficient gulf moisture and build instability.
That said, the odds of reaching or exceeding 500 joules CAPE on
the GEFS has increased to 40-50% over southwestern WI, and at
least 3 of 30 viewable ensemble members approach 1000 joules
somewhere in the region, hence we're not completely in the clear
yet. The intensity, propagation speed, and track of the clipper
system will be monitored.

Dry weather expected Wednesday as high pressure tracks through the
region behind the departing clipper system. Ridging in the jet
stream is expected to gradually build into the Midwestern CONUS
through late next week, yielding a warming trend. As seen on the CPC
6-10 and 8-14 day temperature outlooks, the ridging and warming
trend are likely to intensify through the end of this forecast
discussion period and beyond.

Sheppard

&&

.AVIATION...
Issued 1200 AM CDT Sat May 9 2026

Broken altocumulus clouds around 10,000 ft continue eastward
across the region through the predawn hours, exiting east. Only
~10-15% chances for any rain from that activity, mostly virga
due to dry air beneath the cloud bases. Same story for the
additional altocumulus (at a similar altitude) behind the cold
front late this morning through this afternoon. Can't rule out a
brief spit of rain, but ceilings / visibility should remain
VFR.

Some marginal LLWS through the predawn hours with light
southwesterly surface winds and ~35kt WSW winds at 2,000 ft
AGL. Currently leaving this out of the TAFs as it is below
criteria. Surface winds veer NW behind the cold front later
this morning and become gusty into the afternoon (20-25kt
gusts, possibly upwards of 30 kt at times). Winds and gusts
subside this evening. A weak backdoor cold front may lead to
some light northeast winds for shoreline terminals tonight. Dry
weather and VFR expected to continue.

Sheppard

&&

.MARINE...
Issued 1200 AM CDT Sat May 9 2026

Low pressure around 29.6 inches along the Minnesota and Canadian
border will move east across Lake Superior through the rest of
the overnight hours. Its cold front will move across Lake
Michigan this morning. Breezy south winds continue overnight
ahead of the front, veering west and decelerating as the front
crosses later this morning. Gusty northwest winds develop over
Wisconsin this afternoon behind the front, which may encroach
into the western nearshore waters (a few 20-30kt gusts possible),
but will decelerate towards the open waters. Another (backdoor)
cold front will sag southwards across the lake late today
through tonight, with a brief period of north winds behind it.

High pressure around 30.3 inches is then expected to move from
southern Manitoba on Sunday to over Lake Michigan by Monday
afternoon. Relatively light and variable winds are expected early
next week.

Sheppard

&&

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

$$

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