NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 040012 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
712 PM CDT Fri Jul 3 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms will persist through the
  mid evening hours, mainly south of a line from the Dells to
  Kenosha. Small chance of severe closer to the IL border.

- The risk for additional areas of showers and storms will
  continue intermittently into Sunday. While severe weather is
  not expected, lightning will be a risk. Keep up with the
  forecast and current conditions if planning to be outdoors.

- Trending quieter early next week.

&&

.UPDATE...
Issued 712 PM CDT Fri Jul 3 2026

Monitoring two areas of convection at this hour across the
region. The most potent of the thunderstorms are located across
northern Illinois. A remnant boundary south of the state line
has become a focus for vigorous thunderstorm development.
Mesoanalysis places the highest instability axis is along and
south of the boundary, which will continue to sag south with
time driven by storm scale interactions/augmentation. Will need
to watch for any left movers in IL that may try to approach far
SE WI. Otherwise, winds aloft indicate a preferred west to east
movement with cold pool conglomeration. So while this activity
is very close to the IL/WI state line, the trend is for these
storms to hug the instability gradient and move to the east-
southeast with time. Recent HRRR runs handle this evolution of
this activity in such a fashion.

The CAMs are not quite showing the showers and few storms
further north, largely west of the Madison area. General trends
are for this activity to persist for at least a few more hours
into the evening. Have upped PoPs and included
scattered/numerous showers and isolated storms. Haven't seen
much lightning with this activity, but it is still a risk. There
is no risk of severe storms with this activity. Will continue to
monitor these showers and potentially spread scattered shower
chances further east of Madison if needed. If they were to
survive, this activity would be mainly light in nature.

Looking ahead to tomorrow, the overall pattern continues to keep
the door open for periodic scattered shower and thunderstorm
development. A primary feature to watch for is any remnant vort
maxes from thunderstorm complexes to the west. Another is
multicell development during the afternoon/early evening (peak
heating and instability). Deep layer shear is less impressive
than the past few days (closer to 25kt) with between 1000-2000
J/kg MLCAPE. Absent any organized boundaries, any scattered
shower/storm development will be more chaotic in nature, posing
a lighting risk. Continue to monitor updated forecast and
current conditions and be prepared to take cover as storms move
through.

Gagan

&&

.SHORT TERM...
Issued 306 PM CDT Fri Jul 3 2026

Rest of Today through Saturday night:

There is a weak signal of 500mb vorticity advection over central
IA right now that is expected to track across southern
WI/northern IL late this afternoon and early evening. This could
trigger a few showers and thunderstorms, mainly south of I-94.
The 17Z HRRR solution seems credible at this time, although it
may be a little to far north with the convection. The severe
threat is minimal since our environment was worked over with the
midday storms, although closer to the IL border there could be a
return of instability to support a stronger storm or two.

A thunderstorm complex should develop Iowa again tonight, and it
should track eastward into northern IL as it weakens. There is a
chance that it could clip southwest and far southern WI in
the morning between 5 and 9 AM.

Saturday Afternoon (Independence Day), scattered showers and
thunderstorms are looking likely during the afternoon (mainly
between noon and 8 PM) due to a shortwave trough tracking
through the region. The forecast soundings show tall, skinny
cape but weak shear. Any storms that develop will be fairly
brief, but slow- moving, so localized heavy rain is possible. If
a strong storm can develop, gusty winds could result from it.
With the warm temperature profile, hail is not a big threat.
Storms should diminish with sunset, as that is also when the
wave is expected to move out of southern WI.

Temperatures will be warm, but not nearly as hot and humid, so
heat headlines are not needed.

Cronce

&&

.LONG TERM...
Issued 306 PM CDT Fri Jul 3 2026

Sunday through Friday:

A mid level trough will swing through MN and WI Saturday night
through Sunday. This could bring scattered showers and a few
thunderstorms during the day Sunday, with some pop-up showers
possible during the nighttime hours.

Monday looks dry with northeast winds that will allow for cooler
high temperatures in the 70s near the lake and lower 80s inland.

The (normal-level) heat will return Tuesday and precip chances
return Tuesday night as an upper trough and weak surface low
pressure trough slowly slide across Wisconsin.

Cronce

&&

.AVIATION...
Issued 712 PM CDT Fri Jul 3 2026

Primary concern over the next few hours is scattered
shower/isolated storm development west of Madison and
Janesville. While the most intense storms will stay south of the
the WI/IL state line, this scattered activity looks to persist
for the next few hours. Locally heavy downpours pose a brief
risk of MVFR visibility, though mainly VFR is expected.
Overnight, showers should decrease in coverage. Guidance
indicates the potential for MVFR visibility from light fog prior
to daybreak, and if confidence increases, will include in the
TAF accordingly.

The door remains open for additional scattered showers and
storms Saturday into early Sunday. Timing is difficult to
pinpoint unfortunately and will continue to hone the forecast as
confidence increases. There is a signal for light/variable winds
to become more east/southeasterly with time Saturday afternoon.

Gagan

&&

.MARINE...
Issued 306 PM CDT Fri Jul 3 2026

High pressure around 30.1 inches will sit over the Appalachian
Mountains and a trough of low pressure will remain over the Great
Plains through tonight. A weak low pressure area will then
organize and slowly move across Wisconsin and Lake Michigan from
Saturday afternoon into Sunday. Scattered showers and
thunderstorms are expected at times through the weekend. Patchy
marine fog will be possible as warm and humid air flows over the
relatively cooler lake.

Cronce

&&

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

$$

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