158
FXUS63 KMKX 110224
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
924 PM CDT Wed Sep 10 2025

.KEY MESSAGES...

- Areas of fog forecast tonight, with some locally dense fog possible
  west of I-39.

- Chances (~20-35%) for scattered showers and thunderstorms late Friday
  evening through Saturday morning.

- High temperatures climbing above normal late this week through
  the weekend, with humidity increasing as well.

&&

.UPDATE...
Issued 924 PM CDT Wed Sep 10 2025

Cloud cover is started to slowly move south and dissipate over
time this evening. While cloud cover is decreasing across
southern Wisconsin you can see clouds building across Lake
Michigan on satellite. This mid level clouds are preventing fog
from developing across portions of Wisconsin and as cloud clear
out patchy fog should expand. The best chances for fog will be
low lying areas specifically river valleys, marsh lands etc.
Not anticipating there to be much if any dense fog, but if
clouds erode quickly, low lying areas west of Madison could get
some patchy dense. Overnight lows are expected to fall into the
low 50s in the west, which will make the dewpoint depressions
lower. Versus the east which will have lows in the upper 50s to
low 60s along Lake Michigan.

Patterson

&&

.SHORT TERM...
Issued 256 PM CDT Wed Sep 10 2025

Tonight through Thursday night:

Synopsis/Mesoanalysis: Water vapor imagery places a broad upper
trough over Lake Michigan this afternoon. Lift from the feature was
responsible for light rain showers & sprinkles this morning, with
regional radars continuing to depict light echoes over east-central
and southeastern Wisconsin at the current hour. The majority of said
echoes are struggling to reach the surface as they encounter a dry
low level air mass, though occasional reports of light sprinkles
have been noted. Any isolated sprinkles will push east of the region
by late afternoon with the departing upper trough. Currently
situated over the Northern Plains, an upper ridge will move into the
upper Mississippi Valley tonight through Thursday, allowing high
pressure currently centered over the Hudson Bay to drift southeast
along the Ontario-Quebec border. This progression will allow for
fair conditions and generally light surface winds through the
duration of the short term period. The combination of mostly clear
skies and light winds will be conducive for areas of fog development
tonight, with the best potential likely to focus along and west of
Interstate 39.

Tonight: With light winds and clearing skies, areas of fog
development are possible after midnight. Tend to think that the best
fog potential will focus along & west of I-39 (where skies will
clear out the fastest), but can`t rule out some development as far
east as the Kettle Moraine. Mesoscale model guidance is hinting at
the possibility for locally dense fog along/west of I-39, though
coverage & favored locations for development remain uncertain. Will
thus be monitoring visibility trends through the overnight hours.
Slow down, use low beam headlights, and allow for extra following
distance if encountering fog while driving late tonight/early
Thursday morning.

Quigley

&&

.LONG TERM...
Issued 256 PM CDT Wed Sep 10 2025

Friday through Wednesday:

Synopsis: Rounding the upper ridge over the Mississippi Valley, a
shortwave trough will cross the state Friday night into early
Saturday morning, bringing chances for showers and thunderstorms to
the region. Activity is forecast to shift south and east of the
region after daybreak Saturday. The aforementioned upper ridge will
slowly migrate into the western Great Lakes Saturday night into
early next week, allowing for a prolonged stretch of largely dry
conditions from Saturday afternoon through Monday. The ridge`s
proximity will also translate to abundant sunshine, allowing for
high temperatures to climb above normal from the second half of the
weekend into early next week. Global forecast guidance indicates
that upper ridging will begin to break down by mid-week, with some
signal for trailing disturbances & returning precip chances during
the Tuesday-Wednesday time frame.

Friday Night through Saturday: Expect showers and thunderstorms
across the region from late evening into the predawn hours. Likely a
testament to overnight timing, machine learning guidance is pointing
toward low severe weather potential in this activity. Will
nevertheless be monitoring trends as more CAM data becomes available
over the next 12-24 hours. Precipitable waters will be increasing
into the 1.3-1.5"+ range, which could translate to some brief heavy
downpour potential in this activity.

Quigley

&&

.AVIATION...
Issued 924 PM CDT Wed Sep 10 2025

Mid to upper level clouds across southern Wisconsin will slowly
move south and dissipate tonight into early morning Wednesday.
Overnight as clouds diminish, winds remain light and temperature
drop there will be a potential for fog to develop. Low lying
areas will have the best potential for patchy fog around 2-4 SM.
Any dense fog that develop is likely to be in low lying areas
west of Madison like LNR, but confidence is low on seeing
visibilites of 1SM or less. Not every terminal will see the
patchy fog, especially eastern airports. Winds will be light
and variable through mid morning Wednesday.

VFR conditions will return to all airports shortly after sunrise
when the fog burns off. Mostly clear skies in the morning will
give way to some fair weather cumulus clouds around 4-6 kft in
the afternoon and evening hours. Light easterly winds in the
afternoon will become light and variable again Wednesday night.

Patterson

&&

.MARINE...
Issued 256 PM CDT Wed Sep 10 2025

Weak low pressure of 1019 mb is centered over the Upper Peninsula of
Michigan this afternoon, which is combining with 1025 mb high
pressure near the Hudson Bay to support generally south to southeast
winds across the open waters of Lake Michigan. The aforementioned
high will settle near the Ontario-Quebec border on Thursday,
allowing winds to shift out of the northeast tonight through
Thursday afternoon. Light rain showers are possible through this
afternoon. An isolated rumble of thunder can`t be ruled out, though
hazards are not anticipated. Patchy fog is possible this evening
through tonight, particularly across the northern half of Lake
Michigan. Widespread dense fog is not anticipated, though trends
will be monitored. High pressure will continue to move east into
Quebec on Friday as 1006 mb low pressure moves into the northern
Great Plains, allowing winds to turn southerly across the waters.
Showers and embedded thunderstorms are expected Friday night into
Saturday. Hazards aren`t currently anticipated in this activity,
though trends will continue to be monitored in coming forecasts.
Winds will turn back out of the northeast Saturday night through
Sunday as 1026 mb high pressure settles along the Ontario-Quebec
border.

Light south to southeast winds continue in nearshore zones through
this afternoon, ultimately turning northeasterly tonight. Scattered
showers are possible through this afternoon as an upper disturbance
crosses the western Great Lakes. An isolated rumble of thunder is
possible in this activity, though severe weather is not anticipated.
Patchy fog is possible this evening and tonight. Widespread dense
fog is not expected, though trends will be monitored. Low pressure
will settle into the Northern Plains on Friday, allowing winds to
shift back southerly. Scattered showers and thunderstorms are
expected ahead of the low Friday night into Saturday. Small Craft
Advisory conditions aren`t currently anticipated through the
duration of the period.

Quigley

&&

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

$$

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