NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 111117
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
617 AM CDT Fri Sep 11 2026

.KEY MESSAGES...

- Patchy fog in low-lying areas early this morning, burning off
  shortly after sunrise.

- Trending drier, but still cannot rule out some isolated
  showers and a rumble of thunder into Saturday morning,
  especially in southwestern Wisconsin.

- Additional showers and storms expected Sunday night through
  Tuesday morning. A few stronger thunderstorms are possible.
  The potential for heavy rainfall is increasing, especially
  Monday and Tuesday.

- Seasonable conditions may return midweek.

&&

.UPDATE...
Issued 618 AM CDT Fri Sep 11 2026

Forecast remains on track. Patchy fog in low-lying areas will
burn off shortly after sunrise. Expecting highs around 80
degrees with southerly winds. Diurnal cumulus are expected, with
no rain expected.

MH

&&

.SHORT TERM...
Issued 1200 AM CDT Fri Sep 10 2026

Today through Saturday night:

High pressure will continue to slide eastward this morning,
meanwhile a surface low is progged to develop and track across
central Canada. As a result, southern WI will be placed in
between these systems and expect to see southerly winds pick up
through the day today. Will see a bit of WAA with the southerly
flow and temps be a degree or a few warmer today than yesterday.
However, moisture advection will be lacking so will feel more
comfortable humidity wise. OVernight temps will also be warmer
with lows dipping into the lower 60s into Saturday morning. May
also begin to see increasing cloud cover overnight aiding in the
warmer temps.

Then the low pressure to our north will gradually work its way
into the Hudson Bay region and drag the cold front across WI on
Saturday. May see some showers along the front upstream make it
in our western areas, given the lack of appreciable PWATs (less
than 1.5 inches), expect a mostly dry frontal passage as this
trend continues on the 00z CAMs. Otherwise will see west to
northwesterly wind shift behind the front later Saturday
followed by cooler, more fall like temps in 50s again.

Wagner

&&

.LONG TERM...
Issued Issued 1200 AM CDT Fri Sep 10 2026

Sunday through Thursday:

High pressure returns to the region for Sunday resulting is a
pleasant seasonal end to the weekend with highs only in the 70s
and lows dipping into the 50s and maybe even cracking into the
upper 40s. This high pressure is not expected to hang around for
too long and quickly shifts east overnight Sunday into Monday
as the pattern becomes a bit more active for the start of the
week. Upstream a trough is progged to lift across the Northern
Rockies and Northern Plains through the day. Ahead of it,
looking at low-level WAA to gradually increase along with
southerly surface winds and moisture advection to lift into
southern WI during this time. Models continue to favor increased
PoP chances (+40%) along the low-level WAA and surface warm
front overnight Sunday through the day on Monday. Then later
Monday night into early Tuesday expect the cold front to swing
through the region as the main low traverses across the James
Bay region.

While, this places southern WI in the warm sector of this
system, a bulk of the latest mid-range guidances is keeping the
upper-level dynamics to our north. Meanwhile any convection will
be driven by low-level WAA, and unseasonable stronger LLJ, and
timing of the cold frontal passage, which this far out is tough
to pinpoint exact details. Also given the trend for more midday
precip chances, may end up limiting instability building into
southern WI and paired with later overnight/early morning timing
of the cold front across our neck of the woods, may ultimately
limit our thunderstorm potential with this early week system.
Nevertheless, still plenty of time for things to shift and if we
see this system slow down and the 40-50 kt LLJ scenarios
materialize, it may be enough for a few stronger storms and
potentially minor flooding concerns for portions of southern
WI. Will continue to monitor over the coming days, but it does
bear watching.

Behind the start of the week system, things are progged to
settle down a bit toward the middle of next week as high
pressure is progged to filter in behind it and bring a cooler
airmass to the area.

Wagner

&&

.AVIATION...
Issued 618 AM CDT Fri Sep 11 2026

Patchy fog may still progress across terminals in eastern
Wisconsin, but is expected to be short-lived and low-lying.
Fog will burn off shortly after sunrise. Winds will become
southerly after sunrise, becoming steady around 10 kt during the
afternoon hours. Gusts around 18 kt are possible along the Lake
Michigan shoreline north of MKE. Diurnal cumulus around 5000 ft
are expected. Winds will remain steady and southerly overnight,
with increasing high clouds. Isolated showers and thunderstorms
become possible in southwestern Wisconsin going into early
Saturday morning along a cold front. Winds turn west, then
northwesterly Saturday as the cold front moves southeastward.

MH

&&

.MARINE...
Issued Issued 1200 AM CDT Fri Sep 10 2026

High pressure along with light and variable winds will linger
over the Great Lakes into this morning. Then expect the high
pressure to shift into the eastern Great Lakes with south to
southwesterly winds picking up over Lake Michigan through the
day as low pressure works its way into the Hudson Bay. While
could see some small craft conditions north of Port Washington,
the strongest gusts are expected to occur across the northern
third of Lake Michigan this afternoon into Saturday and may
briefly approach gale force at times. The low pressure will
gradually slide eastward through the weekend and drag a weak
cold front across the Upper Great Lakes region on Saturday
shifting winds to the west-northwest by Saturday night. Will
then see winds gradually lessen through the day Sunday as high
pressure builds across the northern Plains and into the Upper
Great Lakes through Sunday evening. Another low pressure then
develops across the Canadian Plains and tracks across Ontario
for the start of the week. This will bring a return of
increasing south-southwesterly wind over Lake Michigan ahead of
this systems cold front, but timing and gusts will depend on
the strength of the low pressure and cold front.

Wagner

&&

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

$$

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