NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 040523
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1223 AM CDT Fri Sep 4 2026

.KEY MESSAGES...

- Periods of showers and storms will be possible through Friday.
  Some isolated severe storms are possible overnight capable of
  gusty winds and hail. Another round of strong to severe storms
  is then possible around daybreak, capable of damaging winds
  and heavy rainfall.

- Drier weather expected for the weekend into early next week,
  with warm and humid conditions persisting.

&&

.SHORT TERM...
Issued 1104 PM CDT Thu Sep 3 2026

Current Overnight through Friday Night:

An isolated supercell thunderstorm has formed out of some
remnant convection on the eastern edge of the 850mb WAA and
capping at the 700mb level. It is generally following a MUCAPE
gradient to the SE as it tracks into east-central and southeast
WI. Given ample effective shear of 40 to 50 knots and CAPE
ahead of the storm, it is expected to maintain it's strength as
it tracks toward the MKE Metro and out over Lake Michigan into
very early Friday morning.

This evening's convection has begun to evolve more like the 00Z
Thursday run of the HRRR rather than its most recent runs this
evening, as the potential for a lead supercell was well captured
by that run. Given more details of that model run starting to
pan out for us in current radar obs, such as convection now
increasing in coverage over north central WI, the rest of the
early morning hours on Friday evolve into a training line of
convection angled from north central WI into SE WI. A heavy rain
threat may then evolve as convection moves through the area.

There's still a bit of uncertain regarding convection over
north central MN and how that will track into the area around
daybreak Friday. If it holds together and tracks along the CAPE
gradient into our area, damaging winds would certainly be a
threat. However, the current convection over north central WI
and our area may sap vital CAPE to sustain the MCS into our area
as the night goes on. For now, the assumption is that the MCS
will make it into our area, with a storms arriving in the 5am to
8am timeframe for the northeastern half of our CWA.

Following the morning storms, it does not appear that the
atmosphere will recover enough to sustain widespread storms
until Friday evening when the stationary front begins to sag
southward near the WI/IL border. Storms Friday evening should be
isolated to widely scattered.

CMiller

&&

.LONG TERM...
Issued 1221 AM CDT Thu Sep 3 2026

Saturday through Thursday:

The frontal boundary will continue southward on Saturday, moving
fairly slowly as it goes. Even though light winds will come
around to northerly Saturday, humidity will remain, and highs
will be in the low to mid 80s. Surface pressure is expected to
increase through the day, and with the front retreating south,
rain chances are not expected. High pressure will then linger
Sunday through Monday keeping us dry. Dew points will remain
somewhat elevated through the weekend as we will fail to get a
push of appreciable dry air into southern WI, though highs will
dip into upper 70s to low 80s. Warm advection then returns
Tuesday with increased chances for more thunderstorms with the
NBM painting 25 to 50% PoPs over the area. Shower and storm
chances then continue through the rest of the extended. CMiller

&&

.AVIATION...
Issued 1203 AM CDT Thu Sep 3 2026

Some lakeshore terminals may see some marine fog through the
early morning hours, provided rain doesn't move overhead.
Thunderstorms are ongoing over east central WI with their
number/coverage becoming more widespread toward daybreak Friday
morning. Ceilings with convection are expected to be between
1500 to 3000 feet. Areas over southwest Wisconsin may miss out
on the lions share of the thunderstorms activity and stay in
VFR. Storms should then largely end during the post dawn hours
Friday morning, before more isolated to scattered redevelopment
occurs Friday evening/night. Winds will remain southerly to
southeasterly early Friday morning, becoming more southwesterly
to westerly Friday afternoon.

CMiller

&&

.MARINE...
Issued 1156 PM CDT Thu Sep 3 2026

Some Marine Dense Fog may form tonight, mainly over the middle
third of the lake, close to a stalled frontal boundary.

Otherwise, the frontal boundary will remain across the Great
Lakes region through Friday. As this frontal boundary waffles
north to south across the lake from day to day, generally east to
northeast winds are expected north of the front, with east to
southeast winds south of the front. On and off thunderstorms will
be possible along and north of this frontal boundary through at
least Friday night. Then high pressure around 30.1 inches builds
over Hudson Bay on Saturday, while low pressure around 29.6 inches
moves into the northern Great Plains. Similar to earlier week
storms, widespread severe weather is not anticipated, though
isolated stronger storms with hail and gusty winds are possible.

CMiller

&&

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

$$

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