NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 110101
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
801 PM CDT Wed Jun 10 2026

.KEY MESSAGES...

- Isolated to scattered thunderstorms this evening with severe
  storms possible toward central WI. Just slight chances for
  storms during the overnight.

- A High Swim Risk is in effect into the early morning hours for
  Sheboygan and Ozaukee Counties. High waves and dangerous
  currents will be likely, and swimming is not advised.

- Multiple rounds of strong to severe storms on Thursday.
  Significant severe storms are possible. Isolated tornadoes,
  damaging winds, and large hail are the main concerns. There
  is a small potential for flash flooding especially in urban
  areas.

&&

.UPDATE...
Issued 800 PM CDT Wed Jun 10 2026

MLCAPE will continue to increase to 1500-2000 J/KG as low to
mid level warm, moist advection ensues ahead of a weakening cold
front over IA. The cold front will mostly dissipate late this
evening into the overnight as the main upper wave over central
MN lifts newd. Before then, severe storms will be possible over
MQT and Green Lake Counties this evening via the line of storms
approaching from Adams County. Wly 0-3 km shear of 30 kts will
support potential mesovortex genesis with this line. The broken
line of strong to severe storms over IA should mostly dissipate
before reaching south central WI, but cannot rule out isold
storms until a drier airmass arrives at 925-850 mb from 08-10Z
over south central WI and 09-11Z over ern WI.


Gehring

&&

.SHORT TERM...
Issued 1215 PM CDT Wed Jun 10 2026

Tonight through Thursday night:

...Severe Weather Potential Increasing This Afternoon...

Rapid thunderstorm development is ongoing over eastern Iowa this
afternoon beneath an approaching MCV. Thunderstorm development
is ongoing within a very unstable environment with sufficient
overlapping effective shear values. Very unstable conditions are
in place downstream across southern Wisconsin, where surface
temperatures have soared into the mid-upper 80s with dew points
in the 70s. The unstable conditions will allow for continuation
of the Iowa storms into southern Wisconsin through the afternoon
hours, with increasing effective shear values allowing for
continued maintenance of storms at severe levels. A Severe
Thunderstorm Watch is now in effect for all of southern
Wisconsin until 7 PM ahead of this approaching activity.

A linear convective mode affiliated with the encroaching storms
will support damaging straight line winds as the predominant
severe weather hazard through this afternoon. Some wind gusts
could be significant (70+ MPH) given an unstable boundary layer
susceptible to downward transfers of higher momentum from aloft.
Line-embedded tornadoes are also possible, particularly in
northeasterly line surges & any mergers with any storm
development managing to occur ahead of the line. Torrential
downpours will also accompany storms, though progressive storm
motions should limit widespread flooding potential in this
initial round of storms. Move indoors and to immediate safe
shelter if a warning is issued for your area this afternoon.

Second disturbance is then forecast to pivot through the area
this evening, bringing additional convective potential along
with it. Peak potential for any storm redevelopment would be
between 7 PM and 1 AM. Coverage & severity of storms will be
heavily influenced by activity this afternoon, with current
trends suggesting that available instability will be heavily
depleted, leaving the intensity and coverage of storms in
question. Will be monitoring trends closely through this
afternoon and evening. Regardless of severity levels, any
redeveloping storms would be capable of producing additional
torrential downpours, which could lead to pockets of flooding in
any locations that are hit this afternoon. Given lower
confidence in preferred training corridors, have held off on any
Flood Watches in this forecast, but will be watching trends
closely through this evening/tonight.

Will then be turning attention to tomorrow's severe potential
following the conclusion of this evening's activity. As a bottom
line, another round of widespread severe storm development is
anticipated, with the most favored locations for storms being
along and south of a boundary laid down by morning
showers/storms. Peak timing for storms will be between 2 to 8
PM. All severe hazards will be possible. Will be monitoring
trends and providing additional details through this evening and
tonight. Stay tuned to the forecast.

Quigley

&&

.LONG TERM...
Issued 1220 PM CDT Wed Jun 10 2026

Friday through Wednesday:

A shortwave trough sitting over WI and a surface low pressure
system are expected to move northeast over Michigan and Ontario,
bringing a surface high to southern WI late Friday into early
Saturday morning. Drier conditions are expected Friday with temperatures
down into the 70s and humidity significantly decreasing.

Throughout Saturday, the potential for precipitation increases in
the afternoon (40-50%) into the evening (50-60%) as the shortwave
trough settles into WI alongside a cold front. Precipitable water
values of around 1.3" increase this potential. Temperatures are
expected to increase alongside humidity throughout the day into
the evening.

Primarily dry and cooler conditions Sunday through Monday as
surface pressure increases across the region and the shortwave
trough begins to move to the east. Shower/storm chances increase
into Tuesday (20-30%) as the shortwave trough begins to sink back
into WI and a surface low enters from the west. A similar chance
for precipitation for later Wednesday (20-30%) as the low pressure
system moves west, with an approaching high over the Plains.

Zawlocki

&&

.AVIATION...
Issued 800 PM CDT Wed Jun 10 2026

Local MVFR Cigs and Vsbys (BR) tnt with isolated to scattered
showers and storms expected. Multiple rounds of strong to severe
storms from late Thursday morning into the early evening. Areas
of MVFR Cigs expected on Thu via broken stratocumulus but also
in the wake of storms.

Gehring

&&

.MARINE...
Issued 1220 PM CDT Wed Jun 10 2026

Showers/storms are expected to move east over Lake Michigan
Wednesday night, with a high potential for precipitation in the
southern half late Wednesday. Increasing fog potential over the
northern half of Lake Michigan Wednesday night, with increasing
potential over the entire lake early Thursday. Continued
southerly winds across Lake Michigan Wednesday night with
potential for gusty conditions.

A cold front/low pressure system is expected to move in Thursday
afternoon (29.76 inches), increasing the potential for
precipitation Thursday, with the chance of some storms becoming
severe. Winds are expected to shift southeasterly ahead of
precipitation, then to Westerly Friday.

Zawlocki

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060 until 4 AM Thursday.

LM...Small Craft Advisory...LMZ643-LMZ644 until 1 AM Thursday.

&&

$$

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