678
FXUS63 KMKX 310756
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
256 AM CDT Sun Aug 31 2025

.KEY MESSAGES...

- Areas of fog possible (~20-30% chance in any given spot) along
  & west of the Kettle Moraine through sunrise this morning and
  once again tonight.

- Dry conditions with a gradual warming trend through Tuesday.

- Shower and storm chances trending upward (~50-70+%) Wednesday
  and Wednesday night along a cold front.

- Below normal temperatures expected Wednesday night into next
  weekend.

&&

.SHORT TERM...
Issued 255 AM CDT Sun Aug 31 2025

Today through Monday:

Synopsis/Mesoanalysis: A broad area of high pressure is centered
from Lake Huron to the Upper Mississippi River Valley early this
morning, resulting in predominantly clear skies and light/variable
surface winds across most of southern Wisconsin. Model analyses
depict weak convergence in the 925-850 mb layer southwest of
Madison, which has encouraged an area of low stratus development
from roughly Rockford to Monroe. With light surface winds and clear
skies allowing for efficient radiational cooling across the
remainder of the region, areas of ground fog have been noted in
observations along the Kettle Moraine and points west. Anticipate
that pockets of fog will continue through sunrise along the Kettle
Moraine and points west. High pressure will linger over the same
general vicinity through tonight, slowly shifting eastward
during the day on Monday. With the synoptic pattern largely
remaining unchanged, additional areas of fog development will be
possible once again tonight along the Kettle Moraine and points
west. Slow down, use low beam headlights, and allow for extra
following distance if encountering areas of fog through sunrise
this morning and once again tonight.

Rest of Overnight: Will be monitoring obs trends through sunrise
with areas of ground fog developing along/west of the Kettle
Moraine. Pockets of < 1 mile visibilities have already been
noted, though drops have been sporadic/temporary given a very
shallow near-surface moist layer. Given the shallow near-surface
moist layer & attendant brief nature to < 1 mile visibility
drops, tend to think that Dense Fog Advisories won`t be
necessary through daybreak, though trends will nevertheless be
monitored. Should sporadic < 1 mile visibility drops become more
widespread, a Special Weather Statement may become necessary.
Budget a few extra minutes of travel time if taking to the roads
through daybreak. Remember to use low beam headlights and allow
for extra following distance if encountering pockets of ground
fog. Conditions will quickly begin to improve after sunrise.

Tonight: With high pressure still in place regionally and
anticipated clear skies, additional areas of fog development will be
possible along and west of the Kettle Moraine through daybreak. Will
be monitoring trends through the overnight period.

Labor Day: Any early morning fog development will quickly dissipate
following sunrise. Mostly sunny skies are expected, with high temps
topping out in the mid-upper 70s.

Quigley

&&

.LONG TERM...
Issued 255 AM CDT Sun Aug 31 2025

Monday night through Saturday:

Quiet weather continues with large scale ridging remaining in large
part over the region but gradually breaking down and pushing east
while high pressure remains entrenched over the Great Lakes region.
This looks very likely to keep us dry through Tuesday before the
high pressure region fully breaks down and the ridge aloft gets cut
off and pushed out to the east with an upper low digging down
through central Canada.

By Wednesday (trending later Wednesday), we will start to see that
upper trough dig down into the western Great Lakes region with a
developing surface low in Ontario pushing east. With plenty of upper
level support and midlevel moisture this surface low will swing a
front through the region. Still plenty of uncertainty on the actual
timing of this but sometime Wednesday it is expected with rain
likely and with a trend toward a later arrival increasing chances
for storms associated with it. This frontal passage will usher in
much cooler temperatures with rapidly falling heights. While
Thursday may end up fairly cool but quiet another upper low will
swing in behind it for Friday and bring another frontal passage with
showers and storms possible. A brief period of well below average
temps and lows in the 40s would be expected Thursday and Friday
nights. Into the weekend heights will rise back up as the upper low
departs with potential for zonal flow and quieter weather overall.

Kuroski

&&

.AVIATION...
Issued 255 AM CDT Sun Aug 31 2025

Largely VFR conditions prevail across southern Wisconsin early this
morning under mostly clear skies. An area of low stratus development
has been noted from Rockford, IL to Monroe, with observations within
the cloud deck suggesting bases between FL040 and FL055. Currently
anticipate that these clouds will remain south and west of MSN and
JVL, but will be monitoring satellite trends through sunrise. If
clouds begin to approach either terminal, BKN040-BKN050 groups would
become necessary. Clear skies prevail across the remainder of
southern Wisconsin, with the combination of sky cover and light
surface winds favorable for patchy FG development through sunrise.
Areas of FG will be scattered, with development predictability low
at any given location. Have thus removed any prevailing VIS
reductions in recent updates at all aerodromes, with the
understanding that TEMPO groups could become necessary if pockets of
FG develop nearby. Any FG will quickly dissipate following sunrise,
giving way to mostly clear skies through the remainder of today.
Currently VRB surface winds will become generally easterly this
afternoon, with VRB conditions once more establishing after sunset.
Additional FG development is possible again tonight along/west of
the Kettle Moraine, though confidence is once more too low to
justify any prevailing mentions at this time.

Quigley

&&

.MARINE...
Issued 255 AM CDT Sun Aug 31 2025

1022 mb high pressure is centered from the Lower Peninsula of
Michigan across the open waters early this morning. The positioning
of the area of high pressure is resulting in generally light
northeasterly winds across the southern third of Lake Michigan,
light and variable winds across the middle third, and light
southwesterly winds across the northern third. This pattern is
expected to prevail through the beginning of the week with high
pressure lingering over the same general vicinity. Southwest winds
will become established Tuesday night as 1006 mb low pressure
develops near Lake Superior. The low will slowly progress toward the
Ontario-Quebec border Wednesday and Wednesday night, dragging a
strong cold front across the open waters in the process. The frontal
passage will result in a gusty northwest wind shift across the
waters Wednesday evening through the day on Thursday. The current
forecast maintains gusts just below gale thresholds (~25-30 kts)
during this time frame, though model guidance trends will be closely
monitored for potential increases to/above gale levels through the
first part of the upcoming week. Showers and thunderstorms will
accompany the passing cold front Wednesday into Thursday. It remains
too early to pinpoint any possibility for waterspouts in this
activity, though forecast trends will be closely monitored. Breezy
west winds will continue through the day on Friday.

Light east to northeast winds will continue in nearshore zones
through the beginning of the week with high pressure lingering over
Lower Michigan. Southwest winds will become established Tuesday
night as low pressure forms near Lake Superior. Said low will drag a
strong cold front across Lake Michigan during the day on Wednesday,
bringing a gusty northwest wind shift Wednesday evening through
Thursday. Gusts could approach Small Craft Advisory thresholds in
some/all nearshore zones during this time frame, with model guidance
trends being closely monitored through the first half of this week.
Showers and thunderstorms will accompany the passing front Wednesday
through at least the first half of Thursday. Breezy conditions will
continue through the end of the week behind the departed cold front.

Quigley

&&

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

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, X, and YouTube at:
www.facebook.com/NWSMilwaukee
www.x.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee