748
FXUS63 KMKX 141906
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
206 PM CDT Mon Sep 14 2026

.KEY MESSAGES...

- Widespread showers with some isolated thunderstorms expected
  this evening into Tuesday morning. Locally heavy rain and
  urban and small stream flooding are possible, especially for
  low-lying and urban areas west of a line from Port Washington
  to Janesville.

- Gale warning and small craft conditions expected for southern
  WI waters this afternoon through early Tuesday morning.

- A High Swim Risk is expected from the Sheboygan County
  beaches south to Kenosha County Beaches this afternoon into
  Tuesday morning due strong onshore winds and building waves of
  4-9 ft.

- Midweek shower and storm chances, but better chances for areas
  along and south of the WI/IL border. Additional shower and
  storm chances into the weekend.

&&

.SHORT TERM...
Issued 200 PM CDT Mon Sep 14 2026

This evening through Tuesday night:

As the high pressure continues to slide eastward this
afternoon, 700- 925mb WAA will continue to spread northeastward
through the remainder of the day. Accompanying this low-level
forcing will also be an influx of moisture. Currently seeing an
axis of +1.5 inch PWATs from the Dakotas thru the mid-
Mississippi River Valley this afternoon and CAMs continue to
show the trend of this moisture axis laying over across the
Midwest tonight through Tuesday morning. This moisture axis
paired with a cold front will be the focus for our moderate to
heavy rainfall potential. 12z HREF and REFS prog similar PWATs
of 1.5-1.7 inches and even potential to see 2 inch PWATs nose
into far southwestern WI. Pair this increased moisture along
with surface cold front/low-level frontogenesis banding along
with unseasonable strong +50 kt LLJ is looking to be enough for
heavier rainfall for portions of southern WI. Accompanying the
heavier rainfall will be a few thunderstorms, but overall
instability (MUCAPE less than 1000 J/kg) remains elevated and
limited in its extent across southern WI. If any storms do
develop, could also not rule out it mixing down some pockets of
gusty winds, but severe thunderstorm potential does remain
limited.

However, the latest 12z guidance suggests the heaviest rainfall
(2 inches or more is favored to set up across IA with the
greatest core of moisture/instability and a secondary band
across central WI more collocated with the cold front and
leading edge of the WAA. Meanwhile our CWA sits in between these
two corridors. While expecting widespread quarter to half an
inch of rainfall across much of the area, given the pairing of
the low-level forcing, strong LLJ, and moisture continue to see
a signal for over half an inch to inch for areas west of line
from Janesville to Port Washington with a consistent signal and
a high (+60%) potential for our western third of the CWA
(Green/Lafayette counties north through Sauk/Columbia counties)
to even see over one inch of rainfall through Tuesday morning,
likely a result of being at the nose of the highest moisture
axis and longer duration of rainfall. While soil conditions are
anticipated to handle these rainfall totals, if we see higher
rainfall rates over the same area for an extended period of
time, then we could see ponding and minor flooding concerns for
low-lying and urban areas. While on the other hand southeastern
WI is looking to see the lower end of the rainfall amounts as
the cold front is more progressive as it swings through this
area and begins to loose the low-level forcing through daybreak.

While this is based on the latest guidance and model trends,
given the mesoscale nature of this setup, there is still a
potential to see the bands of heavy rainfall just outside our
area to shift through the evening. With southern WI being just
on the edge, it is not out of the realm of possibility to see
the heavier rainfall cores shift into our area, especially if
things time out differently than the current trends, more
widespread thunderstorms develop, and/or end up setting further
south. So will continue to monitor trends through the evening
and does bear watching. Nevertheless, this system tonight into
Tuesday is looking to bring some beneficial rainfall to the
area.

While some light showers may linger into the early afternoon,
expecting the bulk of the showers and storms to move out of the
area by late Tuesday morning as the cold front pushes through
southern WI through the day. After the rain may see temps warm
into the 70s, but gradually fall through the evening dipping
into 50s to around 60s overnight as high pressure begins to
build down across the Upper Midwest.

Lastly with stronger south-southeasterly winds off of Lake
Michigan developing this afternoon into Tuesday morning, expect
waves to build to 4-9 ft creating life-threathening swim
conditions and currents fro all southern WI beaches. Highest
waves up to 9 ft are expected for Sheboygan and Ozaukee
counties, with 4-7 ft waves for beach south. Thus a Beach
Hazards Statement is in effect and be st to stay out of the
water and away from dangerous areas like piers and breakwalls!

Wagner

&&

.LONG TERM...
Issued 200 PM CDT Mon Sep 14 2026

Wednesday through Monday:

While the previous days cold front slides south into IL/IN
region, expect it to stall across that area for Wednesday.
Meanwhile, models prog high pressure to build across the Great
Lakes for midweek. However, depending on how far south each of
these features sets up will determine our rain chances through
the second half of the week. Continue to see the GFS/GEFS trend
toward a more southward extent of this high pressure thus
limiting the shower/storm activity along the low-level WAA and
ahead of the stalled front to our south. Meanwhile the ECMWF/EPS
is more in favor of the low-level WAA and associated
showers/storms to trend far enough northward to overcome the
subsidence from the surface high and has been more of an
influence on the NBM PoP chances. Ultimately, will depend on
placement, but for now will continue to maintain some PoP
mentions especially for far southern portions of the CWA
Wednesday and Thursday.

Otherwise, expect a taste of fall for the second half of the
week and upper-level zonal flow dominates the the pattern with
daily highs in the 60s/70s and overnight lows in the 50s to
around 60F.

Toward the end of the week expect the pattern to shift as long
range models prog trough to develop over the Pacific Northwest
during the day Friday and drift across the central CONUS through
the weekend. As this systems develops and traverses into our
neck of the woods, expect to see a more active trend heading
into the weekend. Continue to see a signal for a weak surface
low to develop over the Plains and lift across the Great Lake
later Friday into Saturday. Will see periodic rain chances
associated with this system as the low-level WAA and warm front
ahead of it could bring a round of showers and storms along with
a bit milder temps. Then as the low passes through WI, it will
likely bring additional chances through the weekend, but exact
timing and amounts remains uncertain given model and timing
difference this far out.

Wagner

&&

.AVIATION...
Issued 200 PM CDT Mon Sep 14 2026

Mid to high level clouds will continue to spread in this
afternoon/evening across southern WI. Most ceilings are
expected to remain in the VFR range, but with some incoming
showers from the southwest, could see MVFR ceilings accompanying
this round of showers, mainly impacting the western terminals.
Cloud cover will persist along with gusty southerly winds this
evening and overnight. Then expecting a cold front to begin to
work its way southeastward across WI bringing additional chances
for moderate to heavy rainfall overnight into Tuesday morning.
Will see more impacts with this round of showers as it may bring
reduced visibilities and MVFR to IFR ceilings overnight/tuesday
morning. While cannot rule out thunderstorms overnight,
especially for the southern terminals closer to the WI/IL
border, confidence remains uncertain as the higher instability
is prog to stay south of WI. Additionally accompanying the
shower/storm chances will be a strong +50 kt LLJ and result in
LLWS concerns after 03z through 12z Tuesday. Gusty southerly
winds gradually turn westerly and shower chances diminish as
the cold front makes its way through southern WI later Tuesday
morning into the afternoon. Expect high pressure and VFR to
return for the second half of the day.

Wagner

&&

.MARINE...
Issued 200 PM CDT Mon Sep 14 2026

Southerly winds continue to pick up this afternoon and evening
and building waves across Lake Michigan as the departing high
pressure moves up the St. Lawrence River Valley while low
pressure tracks across southern Manitoba and into Ontario. As a
result expect wind gust of 25-40 kt across the lake overnight
into Tuesday morning. Gales are expected across the all open
waters as well as central/northeastern WI nearshore waters north
of North Point Lighthouse, while high end small craft
conditions for areas south through tonight. Thus Gale Warnings
and Small Craft Advisories go into effect this afternoon
through tonight. Will then see winds ease from south to north
through early Tuesday morning and marine headlines drop off in a
similar fashion, but gales linger longer into early Tuesday
afternoon. Then as the cold front slides across the lake, expect
more northerly winds and high pressure to fill in behind it for
Tuesday evening into Wednesday. Winds remain north-northeast
through the end of the week, but southerly winds return on
Friday ahead of another system progged to work its way across
the region through the weekend.

Wagner

&&

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

     Beach Hazards Statement...WIZ066-WIZ071-WIZ072 until 7 AM
     Tuesday.

LM...Gale Warning...LMZ080-LMZ366-LMZ565-LMZ567-LMZ643-LMZ644-
     LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-
     LMZ872-LMZ874-LMZ876-LMZ878...9 PM Monday to 7 AM Tuesday.

     Gale Warning...LMZ261-LMZ362-LMZ364-LMZ563...9 PM Monday to 1
     PM Tuesday.

     Small Craft Advisory...LMZ643-LMZ644 until 9 PM Monday.

     Small Craft Advisory...LMZ645-LMZ646 until 7 AM Tuesday.

&&

$$

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