NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 071021 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
521 AM CDT Tue Jul 7 2026

.KEY MESSAGES...

- Shower and storm chances increase Wednesday into Thursday. Low
  chances possible Wednesday morning (15 to 30 percent) north of
  I-94, with better chances (greater than 50 percent) Wedensday
  evening into Thursday morning for all of southern Wisconsin.

- Storms later Wednesday afternoon and evening may produce
  strong winds, cloud-to-ground lightning and some hail. The
  better chances would be north of a Madison to Sheboygan line.

- Locally heavy rainfall and localized ponding/flooding may also
  occur later Wednesday afternoon into Thursday night, due to
  increased moisture and slow moving nature of the system.

&&

.UPDATE...
Issued 521 AM CDT Tue Jul 7 2026

The line of showers and storms in northwest and west central
Wisconsin has fallen apart, with some residual anvil cirrus
clouds moving through at least western parts of the area into
this morning. There may still be patchy dense fog in the river
valleys in south central Wisconsin early this morning.

Otherwise, another dry and warm day is expected today, with an
east to southeast lake breeze developing near Lake Michigan by
midday into this afternoon. Highs should reach the middle 80s
inland, with upper 70s to around 80 degrees near the lake before
the lake breeze develops.

It appears that there is potential for strong winds with the
storms that develop ahead of a cold front later Wednesday
afternoon into Wednesday evening. There seems to be enough mean
layer CAPE (up to 1500 to 2000 J/kg or so) with 20 to 30 knots
of deep layer bulk shear to bring this risk for areas mainly
north of a Madison to Sheboygan line.

There is still some uncertainty with timing, as some CAMs are
slower with bringing in the storms until Wednesday evening. In
addition, some have this activity weakening as it moves into the
area. Still, there seems to be enough potential to warrant the
Slight Risk for severe storms from SPC for that period. Will
continue to evaluate this setup as we get closer to that period.

Also, precipitable water values approach 2.00 inches or so
later Wednesday afternoon into Thursday night. The frontal
boundary slowly shifts southeast through the area, with storms
possibly moving over the same locations. So, this setup may
bring locally heavy rainfall and localized flooding potential.

Wood

&&

.SHORT TERM...
Issued 1201 AM CDT Tue Jul 7 2026

Today and Tonight:

Light and calm winds overnight into early morning hours will
continue as surface high pressure continues to work its way
southward across the area through the day. Could see some patchy
fog develop across portions of the Wisconsin River Valley as
temps drop through the early morning hours. Will be keeping an
eye on the line of thunderstorms trekking across MN and
northwest WI tonight as a few showers may clip the western
portions of the CWA, however, with the drier air and subsidence
from the surface high, most 00z CAMs have this activity
weakening before clipping our neck of the woods.

Otherwise, expect temps to climb into lo to mid 80s this
afternoon with mostly clear skies and plenty of sunshine. Winds
continue to remain light and given the increased thermal
gradient between inland temps and cooler Lake Michigan temps,
expect a lake breeze to develop and track inland through the
afternoon bringing cooler temps to lakeshore areas along with a
period of breezy winds. Overnight will remain mild with lows
only dipping into the low to mid 60s as the surface high
continues slide south and east of the area through early
Wednesday morning.

Wagner

&&

.LONG TERM...
Issued 1201 AM CDT Tue Jul 7 2026

Wednesday through Monday:

Will see the pattern turn a bit more active for Wednesday into
Thursday as mid-level shortwave trough is progged to traverse
across the region later Wednesday into Thursday. However, this
wave develops upstream across the northern Plains Tuesday and
looks to trigger convection across the Dakotas/MN. Some models
hint at this upstream activity lingering overnight tracking
eastward as an MCS into Wednesday morning and may clip portions
of central WI. Thus have added some low end PoP chances for
Wednesday morning for northwester portions of our CWA.

However, the better shower and storm potential for southern WI
will be later in the day Wedensday into the overnight hours as
the mid- level shortwave trough and associated mid-level
vorticity track across WI aligning with a slow moving cold front
and weak surface low feature under the right entrance region of
a sub-100 knot upper- level jet. The alignment of the forcing
paired with increasing PWATs of 1.5-2.0 inches supports 50-90%
PoPs. While timing of this activity remains in question as it
gradually trends slower and moving through more overnight into
Thursday timeframe, there is still models progging +1000 J/kg of
MUCAPE with minimal deep layer shear 20-30 kt Wednesday
evening. This would be enough to support thunderstorm
development with the initial activity and while a stronger storm
or two capable of producing small hail and localized gusty
winds cannot be rule out, the potential continue remain on the
lower side (5% chance per SPC convective outlook).

Overnight Wednesday will see the instability diminish, but slow
moving cold front and moisture is expected to persist, thus PoP
chances continue through Thursday morning. Given the moist
environment and slow moving nature of this activity, would not
be surprised to see some of the showers move over the same areas
for a period of time, which may lead to localized
ponding/flooding, especially if higher rain rates of +1"/hr
materializes, especially with any taller convection. But the
GEFS and EPS members probs of greater than 1" remain on the
lower side (<20%). Nevertheless, potential for heavy rainfall
will be there through Thursday morning and will have a better
idea as the CAMs come more into frame.

Then looking to see off and shower chances continue into
Thursday afternoon as the cold front sags through the area. Some
models prog additional development along the slow moving
boundary Thursday afternoon as an additional mid-level feature
tracks across the region. However, continue to see a deeper
shortwave trough take shape across the Central Plains track
into IA/IL/IN through the day Thursday, which may end up pulling
the cold front through faster than current forecast.

Otherwise, end of the week may start off drier as northwesterly
flow sets up across the region, but models disagree on upper-
level wave passages timing and strength. The 00z GFS is most
aggressive and faster of the models trekking a trough through
the area Friday which could bring additional shower/storm
chances, while the ECMWF is not as bullish and favors high
pressure settling across the area into the weekend.

Wagner

&&

.AVIATION...
Issued 521 AM CDT Tue Jul 7 2026

The line of showers and storms in northwest and west central
Wisconsin has fallen apart, with some residual anvil cirrus
clouds moving through at least western parts of the area into
this morning. There may still be patchy dense fog in the river
valleys in south central Wisconsin early this morning.

Otherwise, another dry day is expected today, with an east to
southeast lake breeze developing near Lake Michigan by midday
into this afternoon. Light and variable winds are expected
inland today. There may be some diurnal cumulus clouds that
develop this afternoon inland as well.

Light south to southwest winds are expected tonight, with some
more middle to high clouds possibly moving in from showers and
storms to the north of the area. There is a small chance (20
percent or so) that Sheboygan may see a few showers move
through into Wednesday morning. Could see patchy fog in the
river valleys once again in south central Wisconsin.

Wood

&&

.MARINE...
Issued 521 AM CDT Tue Jul 7 2026

High pressure around 30.1 inches will remain in place over the
Upper Great Lakes region today. Expect developing south winds
over northern portions of the lake, with light and variable
winds to the south. South southwest winds should then increase
tonight and become gusty and southerly Wednesday, as weak low
pressure around 29.8 inches and an accompanying cold front
approaches from the Northern Plains. Gusty southwest winds
Wednesday night will become northwest to north behind the
frontal passage Thursday into Friday, with high pressure around
30.0 inches building into the the Upper Great Lakes region.

Wood

&&

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

$$

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