330
FXUS63 KMKX 311918
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
218 PM CDT Sun Aug 31 2025

.KEY MESSAGES...

- Some fog possible is possible again later tonight into early
  Monday morning, mainly along and west of the Kettle Moraine.

- Shower and thunderstorm chances continue to trend upward (50
  to 70 percent or higher) Wednesday into Wednesday night along
  a cold front.

- Below normal temperatures expected Wednesday night into the
  weekend.

&&

.SHORT TERM...
Issued 218 PM CDT Sun Aug 31 2025

Tonight through Monday night:

High pressure will remain just east of the area during this
period, with dry conditions expected to continue. Some fog is
possible again later tonight into early Monday morning, mainly
along and west of the Kettle Moraine. Chilly lows in the upper
40s tonight should be below the lowest dew points this
afternoon, so patchy fog is forecast. This fog may be more
shallow in nature, except in low lying areas and river valleys.
The best chances look to be in far western portions of the area.

Light and variable winds tonight and Monday night are expected,
with light east to southeast winds on Monday. Some diurnal
cumulus may occur again in the late morning and afternoon on
Monday. Highs Monday should reach the middle to upper 70s, with
lower 50s away from the lake Monday night. There may not be much
fog Monday night, with low temperatures staying above the
Monday minimum dew points.

Wood

&&

.LONG TERM...
Issued 218 PM CDT Sun Aug 31 2025

Tuesday through Sunday:

500 mb flow becomes northwesterly on Tuesday, as a broad upper
level low develops over south central Canada. The high at the
surface should slide further east, but allow for another dry day
with light southwest winds developing. Highs should be in the
middle to upper 70s once again.

Models and 500 mb cluster analysis continue to show a deepening
500 mb low shifting southeast into the western Lake Superior
area by 00z Thursday, with the main 500 mb low lingering
somewhere over northern Ontario into Saturday. At the surface, a
cold front is expected to push southeast through the area
Wednesday afternoon and early evening, exiting to the southeast
by later Wednesday night.

There is ample moisture and upward vertical motion with the
front, so the trend for higher PoPs of 50 to 80 percent looks
reasonable for Wednesday, with decreasing PoPs Wednesday
evening. Showers and some thunderstorms are expected with the
front. At this time, forecast soundings are showing tall, skinny
mean layer CAPE with the best deep layer bulk shear values
behind the front. Thus, not expecting any severe weather.
A solid 0.25 to 0.50 inches of rainfall may occur, with locally
higher amounts possible.

Various vorticity maxima with differential CVA rotating through
the area at times Wednesday night into the rest of the week may
bring periodic chances for showers. There is also a secondary
cold front that may push through the area later Thursday night
or Friday morning, which may help focus a round of showers. Kept
20 to 30 percent PoPs for this period.

Cold air advection on northwest winds should bring much cooler
temperatures into the area Wednesday night and linger into
Saturday. Highs Thursday may only reach the upper 50s to around
60, which are close to record low maximum temperatures at
Milwaukee and Madison. Below normal highs in the middle 60s for
Friday and Saturday are forecast, with lows in the lower to
middle 40s. These values have been highlighted by ensemble
trends and the NBM. High pressure moving into the region for
the weekend may bring quiet weather, with slowly moderating
temperatures.

Wood

&&

.AVIATION...
Issued 218 PM CDT Sun Aug 31 2025

Scattered diurnal cumulus clouds around 3500 to 4000 feet AGL
should linger until sunset, with light easterly winds.

High pressure will linger over the region into Tuesday, which
will continue to bring dry conditions and light winds. The light
winds and clear skies later tonight may allow for another round
of shallow fog with 1 to 5 mile visibility possible along and
west of the Kettle Moraine, affecting the Madison, Janesville
and perhaps Waukesha terminals. Most of this may be shallow in
nature, with more concentrated areas of fog in river valleys and
low areas.

Light and variable winds tonight will become east to southeast
and remain light on Monday, with more scattered diurnal cumulus
clouds with ceilings around 3500 feet AGL possible by midday.

Wood

&&

.MARINE...
Issued 218 PM CDT Sun Aug 31 2025

High pressure around 30.3 inches will linger over the region
into Tuesday, which will continue to bring light winds over Lake
Michigan. Southwest winds will become established Tuesday
night, as low pressure around 29.6 inches develops near Lake
Superior.

The low will slowly move to the Ontario and Quebec border
Wednesday and Wednesday night, dragging a strong cold front
across Lake Michigan. The frontal passage will result in a
gusty northwest wind shift across the waters Wednesday night,
with gusty winds lingering into Thursday.

The current forecast winds remain below gale force thresholds
during this period for the open waters, though increases to or
above gale force may occur in later forecasts. A Small Craft
Advisory will likely be needed for the nearshore waters, for the
gusty winds and building waves.

Showers and thunderstorms will accompany the passing cold front
Wednesday into Wednesday night. It remains too early to
pinpoint any possibility for waterspouts with this activity and
any showers the rest of the week, though forecast trends will be
closely monitored. Breezy west winds will continue through
Friday.

Wood

&&

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

$$

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