973
FXUS63 KMKX 161851
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
151 PM CDT Wed Sep 16 2026

.KEY MESSAGES...

- Isolated sprinkles/showers possible near the Wisconsin-
  Illinois border through this afternoon, with better chances
  (20-40%) for scattered showers across the area tonight into
  Thursday morning. Best chances near the WI/IL border

- Higher chances for showers and storms arrive Friday-Friday
  night, continuing off & on into early next week. Will be
  watching for locally heavy rainfall Friday through Saturday.

&&

.SHORT TERM...
Issued 145 PM CDT Wed Sep 16 2026

Tonight through Thursday night:

Continuing weak chances for showers near the WI/IL border is to
be expected given increased mid level moisture and some WAA but
most of the precip will be kept further south with the higher
pressure over the region keeping precip further south where the
better upper level forcing is. However, as the stronger portion
of the high pressure pushes out tonight we will see increased
rain and even weak storm chances as some upper level shortwave
energy slides it with even some weak LLJ helping out with some
WAA. Another high pressure will strengthen and push into south
central Canada nudging into the western Great Lakes. This will
again shove precip chances largely out of the area to the south
Thursday morning. Though there is some uncertainty on to what
degree precip will be pushed southward and there will remain
weak chances near the WI/IL border through the day Thursday.

Thursday night, things will quiet down for a period as the high
pressure swings through the Great Lakes region. This will be
ahead of an impending low pressure system expected to push in
Friday.

Kuroski

&&

.LONG TERM...
Issued 145 PM CDT Wed Sep 16 2026

Friday through Wednesday:

Latest models have shown the exit of the high pressure slowing
down and thus the approaching low and corresponding precip
expected has also slowed down. However, Friday, later during
the day we should start to see precip gradually push in from the
west and overspread the region by the late overnight hours with
precip potential lingering through much of the day Saturday.
Deep moisture with strong WAA from a moderate LLJ as well as
upper level shortwave energy the forcing and moisture are plenty
enough. This is all in addition to very strong Fgen. While
strong storms are not expected with this system, the PWATs over
2 inches for much of the event lend itself to the thought that
it could be a very efficient rainfall with some lightning
intermittently.

The prolonged nature of this event in combination with its
potentially high efficiency does yield some concerns about
flooding potential, especially in the areas with highest Fgen.
While flash flooding given the style of the event is unlikely we
cannot completely rule out flash flooding style impacts with
potential for significant ponding of water. However, generally
this is not expected to cause major concerns. Rivers are not
expected to be significantly impacted either given the lower
river levels and dryness of soils overall which should allow
(with non- thunderstorm rain) for decent infiltration and less
runoff. There still remains some questions about whether models
are overdoing the potential rain amounts but the result of this
should largely come down to track, speed and the efficiency of
the system which is still somewhat in doubt so we will have to
continue to monitor these aspects to better understand what
this event might look like. In addition, latest models are also
prolonging the exit of rain as well keeping rain potential into
and potentially even through Sunday as a secondary low may lift
far enough north to bring additional high efficiency precip to
parts of the CWA though its worth mentioning that there is
higher uncertainty due to the interactions with the developing
high in southern Canada with the low.

This may very well continue into Monday as well as what appears
to be a tertiary low ejecting from the central US brings another
round of potential precip to southern WI. Uncertainty remains
high out this far but models are in fairly good agreement on
this. This could make for 4 straight days of rain and potential
for higher end amounts. This will be something to watch as it
could introduce potential for 3-5 inches of rain with pockets of
over 7 inches from Friday through Monday. Rain Monday does
appear to at least be lighter in nature due to the PWATs coming
back down but PWATs likely remain high (>1.75 in) through
Sunday.

Into midweek, forecast becomes much more uncertain and while
much drier conditions should be expected generally it is not do
say that we will not see any storms or showers just that we do
not expect an all day rain situation. Some upper level
trough/shortwaves could play a role in exactly what to expect
for the midweek period with chances for showers/storms possible.

Kuroski

&&

.AVIATION...
Issued 140 PM CDT Wed Sep 16 2026

Quiet conditions for the most part for the rest of the day today
and into the evening with VFR conditions expected, though a few
pockets of MVFR CIGS will be possible, especially closer to the
WI/IL border. Into tonight we will start to see some isolated to
scattered showers and storms push in from the west with more
widespread showers and perhaps even a few storms near the WI/IL
border. Overall the chance for showers has decreased with precip
looking more isolated than previous model iterations though near
the border will feature the best chances for showers and storms.
In addition during this period MVFR to even IFR CIGS should be
expected that will carry on after rain pushes out through at
least the early morning hours Thursday. With any rain showers
expect potential for at least minor VSBY degradation. Otherwise
expect largely light east winds turning northeast Thursday
morning.

Kuroski

&&

.MARINE...
Issued 145 PM CDT Wed Sep 16 2026

High pressure around 30.4 inches continues to track east across
southern Ontario with mostly northeast winds. Predominantly
light and variable winds expected late tonight through Thursday
as high pressure continues to build eastward and additional
reinforcing high pressure builds back in across the Canadian
Prairies.

Breezy east to northeast winds may then develop Friday into this
weekend as low pressure around 29.8 inches develops in the
central Plains and lifts into the Upper Midwest by Saturday.
Gusty southeasterly winds develop Saturday as low pressure
approaches, crossing the southern portion of the Lake as high
pressure continues across Ontario, bringing continued generally
easterly winds and perhaps gales at times throughout the day.
Saturday night, winds turn northeasterly, continuing through
Sunday. Gale potential diminishes late Saturday night, although
gusts around 30 kt are possible through Sunday for the southern
two-thirds.

Kuroski

&&

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

$$

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