304
FXUS63 KMKX 160241
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
941 PM CDT Wed Oct 15 2025

.KEY MESSAGES...

- Light rain is possible (20-40%) Thursday night into Fri
  morning.

- Better chances (60 to 80 %) of showers and a few thunderstorms
  along a cold front late Friday night through Saturday. The
  forecast progression of this front is trending slower.

&&

.UPDATE...
Issued 940 PM CDT Wed Oct 15 2025

High pressure is centered over Lake Superior this evening,
resulting in generally east to northeast winds across southern
Wisconsin. The prevailing synoptic flow has allowed drier
boundary layer air to work in from the northeast, which has been
most evident in increased cloud bases across southern
Wisconsin. Moisture remains sufficient for cloud cover at and
above 900 mb, with forecast soundings showing said moisture
remaining through the overnight. Thus anticipate at least broken
clouds to stick around across the majority of southern Wisconsin
tonight, resulting in low temperatures only a few degrees
cooler than current obs in most locations. Will be monitoring
for fog development over east-central and southeast Wisconsin,
though formation will be highly dependent on any decoupling.
Trends will be monitored through daybreak.

Responding to increasing upper divergence & attendant warm
advection in the 925-700 mb layer, showers and isolated
thundershowers are starting to fill in across northwest Iowa.
Expect development to continue through the overnight, with
activity moving east-northeast through dawn. May see some of
this activity clip areas primarily north & west of Madison after
sunrise. Additional chances for rain enter the forecast Thursday
afternoon and evening.

Quigley

&&

.SHORT TERM...
Issued 351 PM CDT Wed Oct 15 2025

Tonight and Thursday:

The pressure gradient will continue to ease this evening into
tonight as high pressure near central Lake Superior continues
east. Low clouds over Wisconsin late this afternoon and should
persist into the overnight hours for much of the state. Ceilings
are very slowly diminishing from the northeast to the southwest,
but at the pace its at and the placement of the front in Iowa
will likely prevent southwestern Wisconsin from clearing at all.
Given this there is some uncertainty in how much areas will
clear overnight into Thursday. Areas that do have clear skies
will have the potential for fog to develop. Not anticipating
any dense fog as winds will be light but not calm and skies may
not be perfectly clear. Eastern Wisconsin has the best potential
for fog. Any fog that does develop will burn off shortly after
sunrise.

Tonight the LLJ will also move back into Minnesota and west
central Wisconsin. The LLJ should shift northward overtime and
be set up over northern to north central Wisconsin by Thursday
morning. A weak shortwave will move over the upper level ridge
during this time, which will kick off additional showers across
the state. For southern Wisconsin, all of our rain will be
driven by the weak lift from the shortwave which should give us
scattered rain showers. The best chances for rain are across
central and northern Wisconsin where the LLJ will be situated.
These areas will also have the best potential for any lightning.
Only the far northwestern counties (Marquette and Green Lake)
have any real chance for a rumble of thunder/flash of lightning,
but chances are very low. Did increase the POPs just a bit
across southern Wisconsin to pull in some 20-40% POPS for
Thursday which are mainly across the northwestern portions of
our area. CAMs in particular dont seem to be handling the weak
lift scenario we are in very well. This is pretty normal for
weak ridge riders and has already shown its hand into todays
rainfall across southwestern WI and north central Iowa.
Southeast WI may not see any rain from this system.

Patterson

&&

.LONG TERM...
Issued 351 PM CDT Wed Oct 15 2025

Thursday night through Wednesday:

As we head into Friday the upper level ridge is expected to move
eastward out of the state. High pressure at the surface in the
eastern Great Lakes Region will move into the New England
States. Wind will turn to southerly across the state as this
high moves away.

Meanwhile a strengthening trough will swing from the Rockies
northward toward the northern Great Lakes Region/Quebec. The sfc
low will develop in the lee of the Rockies and should track from
there to the northern Plain and then into Canada heading toward
James Bay. An associated cold front will move east into
Wisconsin late Friday night into early Saturday afternoon
bringing widespread chances for rain. Guidance continues to
ever so slight shift this frontal passage later in time (slowing
it down). Regardless a band of showers and some thunderstorms
should move through the area along the front. WAA out ahead of
the front and strong Fgen along it should produce more
widespread rain and thunderstorms. Given this can`t rule out the
potential for a stronger storm or two if the front continues to
have a later the progression of the front. This would cause
storms to develop during peak heating Saturday. Deep layer bulk
shear is good and may not take much instability to get some
stronger storms with gusty winds to occur. Still uncertainty
with this potential, so keep up with the forecast.

The precipitation should end fairly quickly behind the front, as
strong cold air advection on northwest winds pushes into the area
by Saturday night. A rather deep trough should then shift
through the region Saturday night into Sunday. Some lingering
moisture may result in scattered showers at times during this
period. Temperatures should cool down to near or a little above
seasonal normal values Saturday night into Sunday. Trends beyond
this point are very uncertain, so will leave NBM PoPs and
temperatures unchanged in the forecast.

Patterson

&&

.AVIATION...
Issued 940 PM CDT Wed Oct 15 2025

High pressure is centered near Lake Superior this evening, resulting
in generally east-northeast winds at all terminals. Said winds have
allowed drier air to begin working into the region from the
northeast, with VFR flight categories becoming established at
all fields over the last couple hours. Will be monitoring for
FG development near Lake Michigan, where skies will attempt to
clear and winds will lighten during the predawn hours.
Confidence remains too low to justify any mentions in the 03Z
update, though trends will be closely watched through tonight.
Currently ongoing over northwest Iowa, -SHRA will continue to
increase in coverage to the west of the region overnight as
upper level lift increases across the Upper Mississippi Valley.
Majority of precip should remain north and west of the area
through sunrise, though impacts can`t be ruled out following
daybreak at MSN. Have thus inserted PROB30 -SHRA groups in the
00Z update, with later updates to the MSN TAF being made as
trends warrant. Additional -RA development is anticipated over
north-central Wisconsin Thursday afternoon, with the southern
edge of activity expanding into the region Thursday evening.
Have added PROB30 -RA groups in the 00Z update at SBM and MKE
given this expected development.

Quigley

&&

.MARINE...
Issued 351 PM CDT Wed Oct 15 2025

High pressure will continue to move east across Lake Superior
through tonight. Light east to northeast winds this evening will
become southeasterly Thursday morning as the high continues to
pull away. Thursday afternoon southeast winds will become breezy
and remain into Friday morning as low pressure in the northern
Plains moves toward James Bay. This low will deepen as it moves
northeast and an associated cold front will move across the
Lake Saturday. Gusty south wind are expected over the lake ahead
of the cold front with a few gale force gusts possible Friday
afternoon through Friday night. This low will further deepen
leading to strengthening northwest winds behind the front for
Saturday night into Sunday. Another period of gales will be
possible behind the front.

Patterson

&&

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

$$

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