NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 090040 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
740 PM CDT Mon Jun 8 2026

.KEY MESSAGES...

- A very humid air mass will linger through this week.

- Showers and isolated thunderstorms will continue this evening
  into tonight.

- Hot and humid conditions expected mid to late week, with some
  potential for Heat Advisory conditions on Wednesday.

- Severe thunderstorms are possible Wednesday and Thursday.

&&

.UPDATE...
Issued 740 PM CDT Mon Jun 8 2026

Showers will continue this evening as weak low pressure slowly
approaches from the southwest. With the loss of daytime heating,
the thunder threat should continue to diminish this evening,
though a few rumbles will be possible into overnight. Overall
rainfall rates should be less this evening into tonight as well.

DDV

&&

.SHORT TERM...
Issued 240 PM CDT Mon Jun 8 2026

Tonight through Tuesday night:

A compact MCV continues to churn over eastern Iowa as dew
points in the low 70s and PWATs from 1.8 to 2 inches continue to
circulate around the feature. A bit of a lull in convection
behind morning activity has allowed for breaks in the sun to
occur in pockets over southern WI. This has allowed for modest
SBCAPE of 1000 to 2000 J/kg to build over the area. The
presence of the MCV and surface instability should support
additional thunderstorms late this afternoon into this evening.
Very heavy downpours will be possible with any thunderstorms
that occur this evening owing to the tropical environment that
will be present. Generally an additional 0.1 to 0.5 inch of rain
is expected areawide into the evening, but far larger local
amounts from 1 to 3 inches will be possible beneath any stronger
storms.

With the potential for water loading in downdrafts this
afternoon, some wind gusts from wet microbursts can't be ruled
out. Shear is far lower than projected yesterday by models,
lessening the potential for an isolated, brief tornado. However,
some funnel clouds can't be ruled out.

The MCV is projected to slowly meander from NE IA over southern
WI tonight, reaching the Lake Michigan shoreline Tuesday
morning, where it then becomes a bit ill-defined in the models
heading into Tuesday afternoon. Some remnant influence from the
MCV, and a low level trigger from a lake breeze circulation may
allow for some scattered pop- up thunderstorms along the Lake
Michigan shoreline Tuesday afternoon. These storms may be
capable of gusty winds and small hail, particularly during the
mid to late afternoon when instability is maximized.

CMiller

&&

.LONG TERM...
Issued 229 PM CDT Mon Jun 8 2026

Wednesday through Monday:

Low to mid level warm advection Wednesday morning may bring in a
line of storms into our southwest. CAM soundings show these
storms being slightly elevated but feature 2000 J/kg of MUCAPE,
and mid level lapse rates around 7 C/km. Some hail will be
possible as these storms move in just before sunrise, with some
potential for gusty winds if the stable layer gets broken
through. Through Wednesday, a warm front is projected to lift
north over the area, exposing southern WI to a hot and humid
environment. Highs will be in the low 90s, amid dewpoints
between 70 and 75 degrees. This will lead to heat indices
approaching 100 and borderline Heat Advisory conditions. We'll
have to watch Wednesday for cloud cover, as increased cloud
cover will decrease temps and heat indices and vice versa.

Wednesday afternoon, diffluent flow aloft from an approaching
trough will kick off thunderstorm activity over central MN.
These storms are expected to quickly form into a line amid the
boundary parallel shear and track toward southern WI Wednesday
evening around and after sunset. GFS and NAM soundings show
great turning in the low levels, but weak flow aloft. This may
support an initial tornado/hail threat over Central MN and
northern WI, but may mean more in the way of wind for us as the
line tracks our way as the weak shear makes the storms outflow
dominant. We'll need to watch timing and where storms initiate,
as that will determine what severe weather hazards we see
Wednesday night. Closer initiation to southern WI and storms
earlier in the evening would support all hazards, rather than
favoring wind.

Thursday, another chance for severe weather exists, but the
threat will highly depend upon where a remnant boundary from
Wednesday night's convection sets up. The presence of the
boundary will drive storm formation Thursday afternoon. Runs of
the RRFS that are in range would suggest all severe weather
hazards would be possible.

Beyond, a front swings through, lowering dew points heading into
next weekend. Ill-defined chances for showers and storms at time
then linger Saturday through Monday.

CMiller

&&

.AVIATION...
Issued 740 PM CDT Mon Jun 8 2026

Showers will continue this evening as weak low pressure slowly
approaches from the southwest. With the loss of daytime heating,
the thunder threat should continue to diminish this evening,
though a few rumbles will be possible into overnight. The chance
for showers will generally wind down southwest to northeast
overnight into Tuesday morning, though a few showers and
isolated thunderstorms may linger in the east

Ceilings are expected to decrease this evening into tonight, as
the low pressure system moves into southern Wisconsin. If fog
develops over Lake Michigan, some lower visibilities will be
possible in the east tonight into early Tuesday, especially
north of Milwaukee.

Light southeast winds this evening will gradually become west to
northwest by Tuesday morning as the low passes through the
region. Winds will likely turn onshore near Lake Michigan by
late Tue morning or early afternoon.

DDV

&&

.MARINE...
Issued 211 PM CDT Mon Jun 8 2026

Warm and humid air brought from the south along a warm front over
the cool lake into the evening and overnight will bring the
potential for fog over Lake Michigan, primarily over the northern
half Monday night into Tuesday morning, with increasing fog
potential in the north Tuesday evening. Showers and thunderstorms
are expected to increase tonight over the southern portions of the
lake.

Continued southeasterly winds over the lake overnight and into
Tuesday morning ahead of an MCV and a surface low pressure,
with winds shifting southwesterly in the south and northerly in
the north. Into Wednesday, westerly winds alongside a pressure
decrease will bring gusty conditions with the potential for
showers/thunderstorms over southern Lake Michigan Wednesday
afternoon and evening.

Zawlocki

&&

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

LM...None.
&&

$$

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