287
FXUS63 KMKX 091539
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1039 AM CDT Wed Jul 9 2025

.KEY MESSAGES...

- Mostly dry conditions expected today. Storm chances may return
  Thursday as an MCV moves through the upper Mississippi Valley.

- Heat and humidity return Friday into Saturday, along with the
  next widespread chances (~60-75%) for showers and
  thunderstorms.

- Brief break from the humidity on Sunday, with muggy conditions
  and afternoon storm chances returning Monday-Tuesday.

&&

.UPDATE...
Issued 1032 AM CDT Wed Jul 9 2025

Low clouds have pushed south behind a secondary trough over
southern WI, leaving most areas north of I-94 mostly cloudy to
partly sunny. Throughout the day, these clouds are expected to
mix to some degree, allowing for further breaks in the clouds to
develop. Otherwise, dry conditions will prevail through today.

CMiller

&&

.SHORT TERM...
Issued 356 AM CDT Wed Jul 9 2025

Today through Thursday:

Synopsis/Mesoanalysis: A broad area of low pressure is centered from
the Wisconsin-Illinois border to Lower Michigan this morning, with a
slowly-moving cold front currently being analyzed along an
approximate Prairie du Chien - WI Dells - Sheboygan axis. With the
loss of daytime heating, shower and storm activity has waned along
the boundary. Winds have gone light/variable to completely calm in
the vicinity of the front, which is expected to allow for areas of
fog development through sunrise across southern Wisconsin. The cold
front will continue to gradually work south across the area through
this morning, ultimately departing by mid-afternoon. With the
boundary lingering into daytime heating across southern zones, a few
isolated showers/thundershowers can`t be entirely ruled out through
mid-afternoon to the south of I-94 and US-18. Hazards aren`t
anticipated in the event that any isolated development occurs.
Surface high pressure will nudge in from Minnesota late this
afternoon into this evening, allowing a modestly drier & more
comfortable air mass to settle in. Forming along the northern
periphery of subtropical high pressure over the Four Corners,
widespread showers and thunderstorms are forecast tonight across the
Northern Plains. While this activity won`t reach southern Wisconsin,
its influences on the broader environment (particularly any outflows
or MCV`s) could provide enough support for an isolated storm to the
west of Madison on Thursday afternoon. Despite the very small precip
chances both today and Thursday, anticipate that the vast majority
of southern Wisconsin will remain dry through the short term period.

Rest Of Overnight: Can`t rule out areas of fog development
through sunrise with mostly clear skies & light/calm surface
winds being observed in the vicinity of the advancing cold
front. How widespread/dense fog will get remains uncertain. Will
continue to watch obs through daybreak. Slow down & use low
beam headlights if encountering areas of fog through daybreak.

Today: The slow-moving cold front is expected to gradually work
south of the WI-IL state line this afternoon. Can`t completely rule
out an isolated shower or thundershower along the boundary/any
points of interaction with the lake breeze, particularly from late
morning into the early afternoon as surface heating ramps up. Given
timing & expected location of the front, have thus inserted some
~15% precip probs to the south of I-94/US-18 through mid afternoon.
Outside of isolated lightning & brief breezy downdraft winds, severe
weather hazards aren`t anticipated in any shower/thundershower
development.

Thursday: Expect a slightly warmer and largely dry day across
southern Wisconsin. Will be watching areas to the west of Madison
during the mid-late afternoon hours (~3-7 PM), as an isolated shower
or storm can`t be completely ruled out. Whether any development
occurs will be highly dependent on the evolution of overnight
convection in the Northern Plains. If any outflow boundaries or
MCV`s affiliated with said convection make it into southwestern
Wisconsin, isolated shower/storm potential would exist. Any isolated
storms would likely be poorly-organized given very weak (~5-15 kt)
effective shear values, though a few stronger wind gusts would be
possible in collapsing cores given the overlap of storm development
with peak heating & deeply-mixed boundary layers. Will thus continue
to monitor model guidance trends through this evening, with the
understanding that the vast majority of southern Wisconsin will make
it through Thursday afternoon dry.

Quigley

&&

.LONG TERM...
Issued 356 AM CDT Wed Jul 9 2025

Thursday night through Tuesday:

Synopsis: Currently centered from British Columbia to the California
coast, an upper trough will progress into the Canadian Prairies
Thursday night, ultimately crossing the western Great Lakes during
the Friday to Saturday timeframe. A broad area of low pressure & an
attendant cold front will accompany the advancing trough at the
surface, and are likewise forecast to cross the western Great Lakes
during the Friday to Saturday time period. Southerly winds will
increase ahead of the features Thursday night through Friday,
allowing Gulf moisture & humidity to stream back into southern
Wisconsin. Widespread shower and thunderstorm chances will thus
return to the area Friday afternoon into Saturday as the upper
trough & surface features impinge upon the warm & muggy air mass
returning to southern Wisconsin. Uncertainties remain regarding the
precise timing of storm development during the Friday-Saturday
timeframe, though most guidance is in agreement that a round of
widespread storms will occur Friday afternoon and evening. Solutions
then separate considerably moving into Saturday, with some
suggesting additional storm development and others pointing toward
dry conditions. Model trends will thus be monitored closely in the
coming forecasts, with additional details being provided as
solutions converge. Continue to monitor the Friday/Saturday forecast
through mid-late week, particularly if planning to be outdoors
Friday/Saturday. Slightly drier air will work into the region on
Sunday behind the departed cold front. Muggy conditions return
Monday into Tuesday, along with afternoon storm chances.

Thursday Night: Will be watching for scattered storm development
with an increasing low level jet & attendant warm advection across
the Upper Mississippi Valley. Expect this potential to remain
confined to generally west & northwest of Madison, where forecast
guidance generally agrees the low level jet & WAA will focus. Could
see some brief heavy downpours in this activity, with organized
severe weather appearing unlikely at this time. Will continue to
monitor trends.

Friday Through Saturday: The next chances for widespread showers &
storms return to southern Wisconsin. As mentioned above, forecast
guidance differs regarding the progression of the encroaching upper
trough & surface low/cold front, leading to different solutions
regarding the potential for 1 or 2 rounds of storms Friday afternoon
through Saturday afternoon. If forcing mechanisms progress quickly
across the western Great Lakes, solutions depicting a single round
of storms Friday afternoon & evening would become favored.
Conversely, if the upper trough & surface low/cold front proceed at
a slower pace, there could be a period of recovery behind Friday
evening`s storms, allowing for additional storm development on
Saturday as the features move through. Will thus be watching trends
closely through mid-late week, and will provide additional details
as solutions begin to converge. With a moist Gulf air mass
entrenched, heavy downpours will be possible in any storms
developing across southern Wisconsin Friday through Saturday. Also
can`t entirely rule out a stronger storm or two given a very
unstable air mass & modest overlapping wind shear (~15-25 kts).
Continue to monitor the forecast through mid-late week, particularly
if planning to be outdoors during the Friday-Saturday time
frame.

Quigley

&&

.AVIATION...
Issued 1039 AM CDT Wed Jul 9 2025

Low clouds have moved in behind a secondary trough this morning
bringing MVFR to IFR ceilings to areas north of a KMSN to KMKE
line. As the day progresses, these clouds are expected to mix,
lift in height, and scatter, leading SCT low VFR clouds this
afternoon. Otherwise winds will be light and northerly to
northeasterly inland, while terminals along the lakeshore may
see northeast breezes between 15 and 20 knots. Dry weather is
anticipated.

CMiller

&&

.MARINE...
Issued 356 AM CDT Wed Jul 9 2025

A broad area of 1016 mb low pressure is positioned across the
western Great Lakes this morning, with a cold front centered over
the middle of the open waters. The two features are resulting in
light winds across Lake Michigan, with northerlies favored to the
north of the front and southwesterlies to the south. A few light
rain showers are ongoing across southeastern Lake Michigan, and are
expected to move into Lower Michigan by sunrise. The aforementioned
cold front will continue to slowly move south today, resulting in a
northerly wind shift across all of Lake Michigan by the early
afternoon hours. Once ongoing showers over the southern open waters
push east, the remainder of the frontal passage is expected to be
dry. Light northerly winds will prevail through Thursday afternoon
as 1018 mb high pressure moves from the Upper Mississippi River
Valley toward Lake Michigan.

A broad area of 1008 mb low pressure is forecast to move into the
northern Great Plains Thursday night into Friday, resulting in a
south to southeast wind shift across Lake Michigan. The area of low
pressure will move into the Upper Mississippi Valley by Friday
evening, ultimately crossing the open waters during the day on
Saturday with an associated cold front. Periods of showers and
thunderstorms will accompany the approaching surface low & cold
front from Friday afternoon through at least Saturday morning. Winds
will shift out of the west by Saturday evening as the surface low
and cold front move east into Lower Michigan.

With light winds ongoing along a slow-moving cold front, areas of
patchy fog are possible in nearshore zones through sunrise. Don`t
currently expect fog to be widespread or dense, but will continue to
closely monitor observations through the predawn hours. Should fog
materialize and become more widespread/dense than currently
anticipated, brief headlines may be considered. Any fog will
dissipate after daybreak, with winds turning northerly behind the
departing cold front by this afternoon. The next chances for showers
and storms arrive Friday afternoon into Saturday ahead of the next
low pressure system and cold front.

Quigley

&&

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

$$

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