024
FXUS63 KMKX 140015 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
715 PM CDT Sun Sep 13 2026

.KEY MESSAGES...

- Widespread showers and scattered thunderstorms are forecast
  Monday night into Tuesday morning. Locally heavy rain and
  urban and small stream flooding are possible.

- Gales are possible Monday night into Tuesday morning across
  the Lake Michigan open waters as increasing south winds
  develop. A Gale Watch has been issued for much of the open
  waters of Lake Michigan, and for the nearshore zones north of
  North Point Lighthouse. A Small Craft Advisory is also in
  effect for late Monday afternoon through the night.

- A High Swim Risk is expected from Sheboygan south to Kenosha
  from late Monday afternoon into Tuesday morning. A Beach
  Hazard Statement is in effect.

&&

.UPDATE...
Issued 715 PM CDT Sun Sep 13 2026

Skies have cleared out and high pressure will move over the
area overnight into early Monday morning. Light to calm winds
will allow for good radiational cooling conditions overnight.
This should bring chilly lows in the lower to middle 40s over
most of the area, with lows around 50 degrees close to the
lakeshore.

No changes to the forecast at this time for Monday into Tuesday
morning. Looking for some clarity on timing and areal extent of
the first wave of showers and some storms into the area Monday
afternoon and early evening, mainly in western and northern
parts of the area.

Still looks like later Monday evening into early Tuesday
morning should be the main period for showers and some storms,
as the low level jet veers over the area. Precipitable water
values remain high, up to 2.00 inches, with possible training of
this activity bringing locally heavy rainfall.

Wood

&&

.SHORT TERM...
Issued 227 PM CDT Sun Sep 13 2026

This afternoon through Tuesday:

The rain has mostly ended over far srn WI with a clearing trend
from the north. High pressure over MN will move across WI tnt
making for excellent radiational cooling conditions. Low temps
in the lower to middle 40s are forecast inland from Lake MI.

For Mon afternoon into Tue, cyclogenesis is expected from the
nrn high plains to srn Hudson Bay. A sly low level jet of 50 kt
will develop over the Upper MS River Valley Mon afternoon then
veer across WI Mon nt-Tue AM. There are timing differences with
the onset of low to mid level warm, moist moist advection and
frontogenesis. Some models and CAMs are slower and mostly hold
off until Mon evening or overnight, while others bring
numerous showers and scattered storms into srn WI Mon afternoon.
Will go with a compromise and forecast PoPs of 20 percent over
far ern WI by late afternoon to 60-70 percent toward WI Dells.

PWATs of 2 inches will then overspread srn WI Mon nt as the
thermal ridge shifts ewd and the low level jet veers into
central and srn WI. The CAMs and models have good agreement in a
sw-ne axis of heavy rain from IA newd to central WI around
midnight. This area of widespread showers and scattered storms
would then lean over with the low level jet into srn WI for the
overnight. The low level jet will begin to weaken after 08Z and
shift south into nrn IL by 12Z. MUCAPE is expected to remain
well below 1000 J/KG and elevated with heavy rain the main
concern. Flash flooding would be possible if persistent training
of storms occur, but there is uncertainty on the longevity of
the heaviest rainfall rates given a weakening trend with the low
level jet. In addition, the overall QPF values are mostly at an
inch or less and the antecedent conditions are fairly dry with
low river levels. Lesser rainfall amounts would then be expected
on Tue as the low level jet and front weakens and shifts into
nrn IL. Overall will emphasize locally heavy rain and the
potential for urban and small stream flooding.

Gehring

&&

.LONG TERM...
Issued 227 PM CDT Sun Sep 13 2026

Tuesday night through Sunday:

Wswly flow aloft will continue for the week with a stationary
front wavering north to south at times, and likely residing
over IL much of the time. High pressure moving across the nrn
Great Lakes for Wed-Wed nt will be a factor in the overall
frontal position. Rounds of warm, moist advection north of the
boundary over srn WI will be possible at times during the week
with additional showers and storms. By the end of the week,
cyclogenesis may accompany a shortwave trough moving ewd across
the Great Plains and bring more showers and storms to the
region. Slightly below normal temps are forecast from Wed-Sun
partly due to the potential for clouds and rain.

Gehring

&&

.AVIATION...
Issued 715 PM CDT Sun Sep 13 2026

Skies have cleared out and high pressure will move over the
area overnight into early Monday morning. Light to calm winds
are expected.

The high will gradually move east of the area Monday into Monday
evening, with southeast winds gradually increasing in strength.
Southeast gusts of 15 to 20 knots should occur Monday
afternoon, with south gusts of 20 to 25 knots Monday night.

Middle to high clouds should move into the area Monday. There
may be a round of showers that moves into western and
northwestern parts of the area during the afternoon, though it
may be delayed until Monday evening.

Ceilings should gradually lower to around or below 1000 feet
AGL later Monday night into early Tuesday morning, as the
showers and some thunderstorms move into the area.

May see some low level wind shear conditions develop Monday
evening into early Tuesday morning, with south to southwest
winds of 40 to 50 knots at 2000 feet AGL.

Wood

&&

.MARINE...
Issued 227 PM CDT Sun Sep 13 2026

Light to moderate northwest winds this afternoon and evening then
becoming light and variable late tonight and Monday morning.
Winds will ease as high pressure around 30.3 inches moves across
the lake into Monday morning.

Winds will then increase and veer to south-southwesterly Monday
afternoon into Tuesday as low pressure around 29.4 inches
develops over Manitoba. Gales appear likely Monday night into the
first half of Tuesday. A Gale Watch has been issued for much of
Lake Michigan and for the nearshore zones north of North Point
Lighthouse. A Small Craft Advisory is also in effect for late
Monday afternoon through the night from Sheboygan to Winthrop
Harbor.

Periods of showers and thunderstorms will accompany the
developing low from as early as Monday evening into Tuesday. Winds
will trend northeasterly and weaken behind a cold front Tuesday
night into Wednesday.

Gehring

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060...4 PM Monday to 1 PM
     Tuesday.

     Beach Hazards Statement...WIZ066-WIZ071-WIZ072...4 PM Monday
     to 7 AM Tuesday.

LM...Gale Watch...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ669-LMZ671-LMZ673-LMZ675-LMZ868-LMZ870-LMZ872-LMZ874-
     LMZ876...7 PM Monday to 1 PM Tuesday.

     Gale Watch...LMZ643-LMZ644...10 PM Monday to 7 AM Tuesday.

     Small Craft Advisory...LMZ643-LMZ644...4 PM Monday to 10 PM
     Monday.

     Small Craft Advisory...LMZ645-LMZ646...4 PM Monday to 7 AM
     Tuesday.

&&

$$

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