334
FXUS63 KMKX 230910
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
410 AM CDT Mon Sep 23 2024

.KEY MESSAGES...

- Areas of fog are possible over northwestern counties later
  tonight.

- Cooler/near normal temps are expected through the start of
  the week with daily highs in the upper 60s and lower 70s.

- High uncertainty in timing and placement for precipitation
  next weekend (15 to 30 percent chance).

&&

.SHORT TERM...
Issued 410 AM CDT Mon Sep 23 2024

Today and Tonight:

Cooler temperatures, drier air and mostly clear skies are in
store for much of southern Wisconsin today. With the cold front
to our east in Michigan and Indiana, a drier air mass will move
into the state bringing dewpoint temperatures in to the mid 40s
to low 50s. With the light winds away from lake Michigan and the
clear skies, there is a small chance for some fog to develop
early this morning prior to sunrise. The best chances for fog to
develop will be in the northwestern corner of our forecast area,
particularly in the low lying areas. The window for this fog to
develop will be small as were looking for the dew point
depression to be at or near zero before the drier air mass
begins to move in.

Outside of this, the beach hazard statement and high swim risk
remains in effect for southern Wisconsin beaches through this
afternoon (into this evening for far southeastern Wisconsin).
This is due to the north to northeast gusty winds and building
waves. The tighter pressure gradient over the Lake will
eventually shift and weaken, which will cause the waves to
diminish later today.

The chance for rain returns to southern and eastern Wisconsin
tonight into Tuesday. A low pressure system will move from the
mid Mississippi valley and is expected to pass near the southern
portion of Lake Michigan. There is still a bit of uncertainty on
the track of this low pressure system. The difference in track
is how far to the south will this low pass. Keep POP chances low
with the with 40% chance being the max across far southeastern
Wisconsin during the early morning hours Tuesday. There will be
a brief period of east winds expected, which should help with
some moisture advection that wraps around the low. Otherwise the
better chances for rain and thunderstorms is expected to stay
to the south.

Patterson

&&

.LONG TERM...
Issued 410 AM CDT Mon Sep 23 2024

Tuesday through Sunday:

As the low pressure system moves out of the southern Great Lakes
Region, guidance has it interacting with a Canadian surface
high. This would likely slow down the forward progression of the
low pressure system causing it to linger a bit over Lake
Michigan and far eastern Wisconsin. So low chance POPs around
15% are expected to persist into Tuesday evening. After this low
pressure system exits, the Rex Blocking Pattern is expected to
set up across the Central CONUS. This pattern will then dominate
through much of the week. This pattern would keep Wisconsin dry
and slightly warmer with highs slightly above normal in the mid
to upper 70s.

Uncertainty returns for the weekend as long term guidance
suggests a tropical system advecting northward out of the gulf
and interacting with the center low pressure system of the Rex
Blocking Pattern. If these two low pressure systems due
interact, its likely that the Fujiwara effect would take over
and cause them to rotate around the center point (kind of looks
likes its rotating around each other for those who are less
familiar with this effect). This brings in a lot of uncertainty
on the track and how this would break down the blocking
pattern. Especially when the strength of the system coming out
of the gulf would be a key factor. Kept to the average among
guidance which introduces some low chance POPs around 30% or
less for the weekend.

Patterson

&&

.AVIATION...
Issued 410 AM CDT Mon Sep 23 2024

Predominately VFR conditions are expected across southern
Wisconsin. Western terminals will have a small chance to seem
some fog develop early this morning under the clear skies, and
light winds. Drier air will be moving from the north which
should limit its development. Not expecting dense fog at this
time, but the best chances for fog or some low stratus would be
low lying areas in the west. Expect visibilites to remain 3 SM
or greater.

Otherwise dry conditions with mostly clear skies are expected
through this evening. Clouds return tonight ahead of an
approaching low pressure system. This low is expected to pass
to our south across northern Illinois into southwestern
Michigan. Some showers will be possible on the northern side of
the low overnight into Tuesday afternoon before the low pressure
system exits.

North to northeast winds today will become easterly for a short
time Tuesday before returning to northerly.

Patterson

&&

.MARINE...
Issued 410 AM CDT Mon Sep 23 2024

Gusty north to northeast winds will persist through this afternoon
as low pressure around 29.9 inches continues east toward the New
England States. High pressure around 30.0 inches will build into
the northern Great Plains as the low moves east keep the pressure
gradient tighter over Lake Michigan during this time. Gusts will
taper late this afternoon into tonight as the high pressure moves
over the northern half of the lake before moving toward James Bay.

The next chance for rain arrives Tuesday morning ahead of an upper
level disturbance, with only slight chances (around 40 % or less)
for thunderstorms over the far southern portion of the lake.
Winds will briefly become easterly as this disturbance moves
through before returning to north to northeasterly. A broad area
of 30.0 inch high pressure will be dominant surface feature
regionally through mid to late week, helping to maintain north-
northeast breezes. Additional rain chances arrive by next
weekend.

Patterson

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066 until 1 PM
     Monday.

     Beach Hazards Statement...WIZ071-WIZ072 until 4 PM Monday.

LM...Small Craft Advisory...LMZ643-LMZ644 until 1 PM Monday.

     Small Craft Advisory...LMZ645-LMZ646 until 4 PM Monday.

&&

$$

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