NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 241105
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
605 AM CDT Wed Jun 24 2026

.KEY MESSAGES...

- Chances for thunderstorms on and off this morning through this
  evening. A Marginal Risk for severe thunderstorms develops
  this afternoon and early evening, with the main hazards
  damaging winds and hail, especially in areas that see clearing
  in the early afternoon hours.

- Active pattern develops Sunday through Wednesday next week.

- A strong warming trend is expected early next week,
  potentially nearing Heat Advisory criteria Monday through
  Wednesday.

&&

.UPDATE...
Issued 550 AM CDT Wed Jun 24 2026

06z guidance remains roughly in agreement with the 00z guidance
for today's thunderstorm setup... The existing elevated
convection (showers and thunderstorms) over northeastern IA and
southwestern WI will continue to track east-southeastward,
crossing southern and southeastern WI through the rest of this
morning. Instability with it will be quite limited (generally
700 joules or less MUCAPE), and the storms will not have an
opportunity to become surface-based, meaning the only real
concern will be lightning. Based on their current motion vector
as well as interim model guidance, these showers (and rumbles
of thunder) should take until at least midday to move clear of
far southeastern WI, and the associated cloud cover will block
much of the sunlight through peak heating today, making it
really difficult for far southeastern WI to destabilize this
afternoon.

For east-central, central, and southwestern WI, a different
story... the existing showers + weak storms and associated cloud
cover should clear out much earlier in the day, perhaps allowing
some of the sunlight at midday / peak heating to get through to
the ground. Nighttime microphysics cloud imagery over the past 3
hours corroborates this assessment, and as I write this (5:45am
CDT) I am seeing mostly clear skies in south-central MN. The
exact effect of the morning convection on this afternoon's
effective warm front remains disputed amongst model guidance,
but the general consensus is for southwesterly surface winds
behind the morning convection to lift it northeastward across
southwestern WI, stalling it diagonally across the CWA (which
could allow it to be a focal point for storms in southwestern
and perhaps south-central WI this afternoon and early evening.
Further north into central and east-central WI, we aren't
expecting this boundary to lift that far north, though some
lighter synoptic southwesterly flow will still be present here,
the clouds should still break apart (particularly further west),
and models hint that your mid-level lapse rates might be a
little bit steeper (which makes conceptual sense closer to the
core of the low pressure system). Hence, the airmass in these
areas may recover this afternoon as well, perhaps enabling some
strong storms in these areas. Generally watching the 2:00 PM to
8:00 PM timeframe this afternoon and early evening for the
stronger storm potential. Frequent lightning, hail, and gusty
winds remain the primary concerns.

Sheppard

&&

.SHORT TERM...
Issued 117 AM CDT Wed Jun 24 2026

Today through Thursday night:

A warm front draped from southern Minnesota through eastern Iowa
will lift northward into this morning as a decaying MCS progresses
eastward along the northern edges of this front. Expecting
overrunning precipitation across the majority of southern
Wisconsin through this morning as the front slowly moves through
the region, with the main threat being lightning. Warm front will
lift into southern Wisconsin after sunrise.

Latest mesoscale modeling shows the weak warm front struggling to
get farther north than the I-94 corridor, resulting in additional
rounds of precipitation through much of the day across the I-94
corridor southward. The parent low finally propagates into
northern Wisconsin during the afternoon hours, with a cold front
slowly progressing southeastward through the state. With
additional rainfall/cloud cover becoming more likely across the
southernmost tiers of counties through much of day, intensity of
storms developing along the cold front is more in question. Areas
farthest north toward central Wisconsin and the Wisconsin River
Valley stand the best chances of seeing isolated stronger storms
due to the increase in instability near the core of the low (still
expected to rise to 1000-1500 J/kg) and the increased shear
values along the front (0-6 km shear around 30 kt, definitely a
downward trend from previous model runs) during the mid afternoon
hours. Storms that do tap into the available ingredients may
become capable of producing damaging winds and hail. Elsewhere,
generally expecting lightning to be the main threat.

Storms along the cold frontal boundary will progress southeastward
through the remainder of the afternoon and evening, with potential
for additional development along the front into the evening hours,
although coverage is expected to diminish (20-40%, isolated to
scattered). Storms will end west to east by midnight, with lows in
the mid to upper 50s. Winds are expected to remain light, but
steady enough to inhibit fog development at this time.

Winds become northwesterly into Thursday as low pressure exits
into Lower Michigan, with an additional shortwave propagating
along the mean flow through central to southeastern Wisconsin
during the afternoon hours, leading to additional scattered
showers and thunderstorms (20-40% coverage). Highs in the mid 70s
are expected.

Winds shift to become northeasterly Thursday night as low
pressure develops in the Middle Mississippi Valley. A few showers
and storms along the north side of the low may progress into far
southern Wisconsin, but probabilities are low due to the low track
through central/southern Illinois (~20%). Lows in the low to mid
50s are expected.

MH

&&

.LONG TERM...
Issued 117 AM CDT Wed Jun 24 2026

Friday to Wednesday:

High pressure builds into the Great Lakes region on Friday, as low
pressure continues to propagate across the Ohio Valley. A few
showers (15-20%) may continue across far southern Wisconsin, but
this likely will trend even lower due to the strength of the
northern high. Easterly winds off Lake Michigan will keep
temperatures cooler in the low 70s in southeastern WI while
temperatures in southwestern WI reach the upper 70s. This pattern
persists through Saturday, but with plenty of sunshine on Saturday
as the Ohio Valley low exits, expect highs in the mid to upper 70s
in southeastern WI and highs in the low 80s in southwestern WI.
Low pressure then developing in the northern High Plains will
shift winds to southeasterly going into Sunday, with WAA and weak
convergence across the area leading to chances for showers and
thunderstorms (15-25%) as low pressure continues to deepen in the
Plains. Temperatures will climb into the mid-80s and even the
upper 80s in areas that do not see showers/storms.

Southerly winds continue through Sunday night, with lows only in
the low 70s. By Monday, plenty of surface WAA combined with
increasing humidity will lead to highs in the upper 80s to even
low 90s (potentially reaching heat index values over 100 degrees).
Winds shifting to become southwesterly as low pressure propagates
into Ontario will allow for high heat index values all the way to
the Lake Michigan shoreline. Monday night into Tuesday, a frontal
feature from the exiting low will bring in scattered shower and
storm potential (20-40%). Some models show this front stalling
through midweek, but confidence in exact timing of any additional
showers and storms remain in question. As high pressure builds
across the Southeast U.S. through early next week, additional heat
and humidity will build into the region. With overrunning cloud
cover, Heat Advisory criteria becomes less confident, but
conditions are ripe for some areas that see additional sunshine
during the daylight hours to also see heat index values above 100
degrees.

MH

&&

.AVIATION...
Issued 600 AM CDT Wed Jun 24 2026

A morning round of showers and weak thunderstorms tracks east-
southeastward across southern WI this morning, taking until
roughly midday to move clear of far southeastern WI. Expect MVFR
visibilities (in some cases briefly IFR) from the moderate to
locally heavy rainfall and some rumbles of thunder. Cloud
ceilings have been generally VFR with this activity so far,
though model guidance suggests a lowering to predominantly MVFR
is likely for most areas later this morning.

Cloud ceilings improve to predominantly VFR in a west to east
manner early this afternoon, but chances for more intense
thunderstorms build in from west to east shortly thereafter.
Gusty winds, hail, and frequent lightning would be a concern
with any stronger storms if applicable, mainly in southwestern,
central, and east-central WI terminals. Generally weaker storm
activity expected as the convection tracks into southeastern WI,
but still a lightning threat.

Storms weaken and clear out in a west to east manner later this
evening. Dry weather likely across the region after midnight
tonight.

Sheppard

&&

.MARINE...
Issued 117 AM CDT Wed Jun 24 2026

Weak low pressure around 29.9 inches in northern Minnesota this
morning will allow for winds to shift to southwesterly as low
pressure pushes eastward through northern Wisconsin through today.
Thunderstorms are expected to develop this evening as low
pressure pushes across the open waters into Lower Michigan,
turning winds to northerly into Thursday. High pressure around
30.0 inches over Ontario and the western Great Lakes will dominate
Friday through Saturday for light northerly winds shifting to
northeasterly. Sunday, low pressure deepens to 29.4 inches in the
northern High Plains, bringing strong southeasterly winds to the
lake. Winds turn southerly into Monday as low pressure exits into
the Canadian Prairies. On and off thunderstorms become more likely
during this time.

MH

&&

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

$$

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