NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 281953
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
253 PM CDT Sun Jun 28 2026

.KEY MESSAGES...

- Expecting hot and humid conditions through much of the week
  leading to hazardous/dangerous heat related concerns due to a
  combination of daytime heat indices in the 90s to above 100F,
  the first stretch of heat this summer spanning multiple days
  beginning Monday, and not much overnight relief with overnight
  lows only in the 70s each night.

- Extreme Heat Warning in effect for all of southern WI Monday
  afternoon through Tuesday. Additional heat headlines may be
  needed for the second half of the week, but some uncertainty
  remains.

- Continued chances for showers and storms this evening, en into
  specially for east-central WI. Then additional daily storm
  chances Tuesday evening through Friday with this hot and humid
  pattern.

- High swim risk conditions for Ozaukee and Sheboygan county
  beaches while moderate swim risk for Milwaukee and Racine
  county beaches for Monday.

&&

.SHORT TERM...
Issued 245 PM CDT Sun Jun 28 2026

Tonight through Tuesday night:

Remnant MCS is trekking across southern WI this afternoon
following along the band of 700 mb frontogenesis and mid-level
shortwave trough. While it is mainly bringing light to moderate
rainfall with the stronger activity following the better SBCAPE
gradient and warm front into northern IL, there has been enough
elevated instability over southern WI for a few flashes of
lightning and rumbles of thunder to occur within the stratiform
region of this complex. Cannot completely rule out seeing this
line reinvigorate some as it moves toward the lake as this area
has had some time to warm up and build up a bit more instability
(MUCAPE of around 500mb based on 18z RAP) and paired with the
synoptic forcing mechanisms and localized MCV forcing. Will be
monitoring radar trends and see if this materializes, if so
could see some gusty winds. in addition to the lightning
threat. Otherwise, expect this shower and occasional thunder
activity to work east through the remainder of the afternoon and
pushing out by the evening.

Then will be another chance for showers and thunderstorms this
evening mainly across the central and east-central WI north of
I-94 as the warm front lifts northward and low-level WAA joins
the remnant 700 mb frontogenesis band and nose of 30-45kt LLJ.
Much of this activity looks widely scattered with light to
moderate rainfall. This activity should progress northward and
exit our CWA around daybreak, but lingering cloud cover may
persist through the start of the morning.

Otherwise, the upper-level ridge axis continues to build over
the region into Monday with overnight lows tonight starting of
in the upper 60s to lower 70s. Then continue to see the hot and
humid conditions settling in over the Midwest. While any
lingering cloud cover may slow the morning temps, expect things
to clear up mid-late morning with temps quickly climbing into
the 80s and 90s by the afternoon. Pair with the dewpoints in the
lower 70s, heat indices of +100F is expected across much of the
area and even expecting to see +105F heat indices. Areas right
along and just inland of Lake Michigan will see the coolest
conditions, but still hazardous heat. Thus have upgraded and
issued an Extreme Heat Warning for all of southern WI Monday
afternoon.

Have elected to continue the Extreme Heat Warning Monday
evening/night as there is not expected to be much relief from
the heat with overnight lows expected in the mid to upper 70s
and even warmer heat indices. Also have extended the Warning
into Tuesday as southern will see another hot and humid day for
Tuesday as the blocking high over southeastern CONUS keeps the
upper-level ridge over the Upper Midwest. Looking at afternoon
temps in the mid 90s and +100F heat indices. while cannot rule
out few stray showers and storms to develop in this muggy
environment, there is not much in the way of forcing to trigger
this activity until later Tuesday.

Overall, the week will start off with a prolonged period of
heat paired with humid conditions resulting in heat related
issues and concerns. Stay weather aware and keep cool and
hydrated.

Lastly increasing southerly onshore flow developing overnight
into Monday will build waves along southeastern WI beaches
resulting in elevated swim risk conditions. Highest waves of 4-6
feet and conditions favoring dangerous currents will be for
Sheboygan and Ozaukee county beaches Monday. Still looking at
moderate swim risk conditions for beaches south along Milwaukee
and Racine county beaches.

Wagner

&&

.LONG TERM...
Issued 245 PM CDT Sun Jun 28 2026

Wednesday through Sunday:

Midweek onward is expecting to see similar set up with the
upper- level ridge situated over the Great Lakes through the end
of the week. Thus, will continue to see hot and humid
conditions with daytime heat indices in the upper 90s to
around/above 100F. Additional heat headlines are possible for
the second half of the week. However, the biggest difference
from the start of the week through the end of the week, is the
increased chances for daily showers and thunderstorms. As noted
yesterday models have the ridge axis slightly further east than
earlier model runs, placing the southern WI under the
peripherals and even within the upper-level jet. Any shower and
storm activity, depending on timing/development as well as
remnant cloud cover may influence temps as well as heat indices
each day Wednesday through Friday. Thus, not as certain on the
higher heat indices at this point and additional heat headlines
(warning/advisory) decision will be taken day-by-day.

Regardless of the heat headlines/thresholds and storm chances,
still looking at periods of daytime heat indices in at least the
90s and above each day along with warm nightly lows for the end
of the week. Thus, prolonged nature of the pattern due to the
blocking high will likely be case for continued heat related
issues/concern across southern WI, especially for vulnerable
populations without easy access to stay cool and those spending
extended periods outside.

There are some hints in the long-range models of the ridge
breaking down a bit toward the holiday weekend with a series of
disturbances tracking across the region, but still plenty of
time for things to evolve and change given the midweek pattern.

Wagner

&&

.AVIATION...
Issued 245 PM CDT Sun Jun 28 2026

Line of light to moderate showers and a few rumbles of thunder
(mainly along and south of I-94) continue through the afternoon
and exits by the early evening. Main concern would be brief
gusty winds and minor reduction of visibility. Then there will
be another chance of showers and storms for east-central WI
later this evening and overnight as the warm front lifts north
and may see a period of lower ceiling to around or even below
MVFR with the overnight activity. Otherwise, the southeasterly
winds this afternoon and evening will gradually turn more
southerly into Monday as heat and humid conditions settle across
the region. Accompanying this pattern shift will be gusty winds
late Monday morning through the afternoon and gusts of 25kt
possible. VFR conditions are mainly expected mid Monday morning
through the evening.

Wagner

&&

.MARINE...
Issued 245 PM CDT Sun Jun 28 2026

Low pressure over the Plains continues to deepen and shift
winds more southerly across Lake Michigan tonight into Monday.
Stronger winds and builds waves will result in small craft
conditions tonight for areas north of Port washington, while
conditions develops Monday afternoon for nearshore south of Port
Washington to Winthrop Harbor. Breezy southerly winds will
persist through midweek as the blocking high over the southeast
US brings hot and humid conditions to the region. Additionally
will see daily thunderstorm chances return for the end of he
week into the weekend.

Wagner

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060...4 AM Monday to 10 PM
     Monday.

LM...Small Craft Advisory...LMZ643...4 AM Monday to 10 PM Monday.

     Small Craft Advisory...LMZ644-LMZ645-LMZ646...noon Monday to
     10 PM Monday.

&&

$$

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