494
FXUS63 KMKX 211434
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
934 AM CDT Fri Aug 21 2026

.KEY MESSAGES...

- Showers & storms through noon. Widespread severe weather not
  expected in this activity.

- Scattered showers and thunderstorms (30 to 50 percent chances)
  with passing cold front are expected this afternoon and
  evening. Damaging winds are the main threat.

- Small chances (20 to 40 percent) for a shower or storm
  Saturday afternoon for portions of east central and southeast
  Wisconsin.

&&

.MESOSCALE UPDATE...
Issued 930 AM CDT Fri Aug 21 2026

Mainly sub-severe showers and storms continue through noon.
Monitoring atmospheric recovery into the afternoon for
additional storm redevelopment (some possibly strong-severe).

East-west line of elevated thunderstorms continues to sag
southeast across the region this morning. Activity is ongoing
near the nose of a 925-850 mb theta-e plume originating from the
Central Plains, with affiliated warm advection continuing to
support the development of new cells along the western periphery
of the line. Given the mechanisms in play, anticipating this
line of storms to make it all the way through southern Wisconsin
through the rest of the morning hours. Have upped precip
probabilities through noon to account for near-term
expectations. Given elevated nature to the storms, in addition
to their separation from a plume of surface-based theta-e &
instability closer to the Mississippi River, not anticipating
much of a damaging wind threat in these storms. Can expect a
brief hit of torrential rainfall and frequent cloud to ground
lightning as activity moves through. Move indoors as these
storms approach.

Once these initial storms depart following the noon hour,
forecast concerns shift toward atmospheric recovery through
early afternoon. Said recovery will reside in the amount of
cloud debris leftover from morning storms, in addition to the
eastward progress of a surface warm front currently near the
Mississippi River. The warm front serves as the eastern bound
of what will become a narrow but unstable warm sector ahead of a
cold front currently near the Twin Cities. The further the warm
front makes it into southern Wisconsin, the greater the area
that will become unstable & favorable for storm re-development
after 3 PM. Will thus be monitoring this progress closely over
the next several hours, as it remains uncertain how far east the
warm front will make it. Anywhere that does become favored for
storm re-development will need to be watched for severe weather
impacts, with large hail, damaging winds, and an isolated
tornado all possible. Stay weather aware into this evening.

Quigley

&&

.SHORT TERM...
Issued 1100 PM CDT Thu Aug 20 2026

Tonight through Saturday night:

Tonight should remain largely quiet outside of a few light
showers nudging into the region but despite some PVA pushing
through and low level WAA the low level moisture may be too dry
initially to bring showers to the ground. Around daybreak
Friday we expect some low level moisture to allow for precip
chances to increase for a brief period in the morning. The
forcing appears to be largely focused along the shortwave with
supplementary WAA and better moisture but CAMs do not seem to
favor widespread showers in the morning with better chances
focused further west closer to the surface front. As the front
pushes east moisture seems to improve into Friday afternoon and
evening. CAMs seem to favor some development of convection
Friday late afternoon on the western half of the CWA with a
secondary development potential into the early evening closer to
the lake. Given higher instability (>2000 J/kg) and enough
shear (30-35kts) we should see a stronger storm or two for a
brief period but the lack of better shear should limit the
potential to just a few storms at most with the primary concerns
being 1 inch hail and brief damaging winds.

Quieter conditions overnight Friday into Saturday morning as the
surface low pushes out. However, Saturday late morning and
afternoon we will likely see a backdoor cold front combined with
lake breeze convergence zone in the nearshore region bring
additional precip chances for eastern portions of the CWA. There
is some uncertainty for this primarily with respect to low to
mid level moisture and how widespread it will be but some
showers and perhaps a few storms will be possible with this. If
we can manage a few storms we could see some become strong
given a decent amount of deep layer shear though this differs
significantly between the CAMs and synoptic scale models so we
will have to monitor those conditions through Friday. This will
be worth monitoring Saturday afternoon given some potentially sneaky
conditions. Chances will rapidly decrease Saturday evening as
we lose instability and forcing pushes out.

Kuroski

&&

.LONG TERM...
Issued 1100 PM CDT Thu Aug 20 2026

Sunday through Friday:

Sunday and Monday will feature high pressure building into the
region keeping things dry through Monday. Things have trended
overall drier into Tuesday with the high pressure lingering a
bit longer with Tuesday night Wednesday becoming our next best
chance for showers and storms as and 850mb front and upper level
shortwave swing through with some WAA. Still some uncertainty
in track and timing but models generally agree on this pushing
through bringing precip with likely some storms as well. In
addition, deep layer shear appears to be strong in the 40-50kt
range which would bring some severe risk if the timing of storms
is into the evening.

After Wednesday, uncertainty increases quite a bit though in
general higher pressure seems to be pushing in with drier
conditions overall more likely.

Kuroski

&&

.AVIATION...
Issued 600 AM CDT Fri Aug 21 2026

Storms (non-severe) are likely for east central WI, but are
looking less likely for south central and southeast WI this
morning. Cloud bases in any storms toward central WI could drop
to 2500ft, but would be around 5000ft elsewhere. Look for
steady southwest winds across southern WI today with a general
lull in storm activity. Then isolated to scattered storms are
expected to develop in south central WI mid afternoon and trek
eastward through early evening. A few strong to severe storms
are possible with damaging winds the main threat. Winds will
become northwest this evening after the passage of a cold front.

Cronce

&&

.MARINE...
Issued 600 AM CDT Thu Aug 20 2026

South to southwest winds will increase today as a low pressure
trough of 29.8 inches approaches southern Wisconsin from the
Minnesota Arrowhead. Thunderstorms are expected at times today
through tonight. The trough will cross Lake Michigan from north
to south tonight and bring a wind shift to the northwest. Then look
for gusty northerly winds to develop along a cold front that will
track from north to south down Lake Michigan Saturday evening. A
few thunderstorms are possible along this front. Northerly winds
will persist through Sunday as low pressure around 29.6 inches
tracks from Lower Michigan to Ontario. Variable winds are
expected for Monday and Tuesday as high pressure of 30.1 inches
crosses the Upper Great Lakes.

Cronce

&&

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

$$

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