NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 180435
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1135 PM CDT Fri Jul 17 2026

.KEY MESSAGES...

- Slight chances for thunderstorms early Sat AM through late
  morning.

- Wildfire smoke is expected to return Saturday night and Sunday
  with unhealthy air and reduced visibility expected.

- High Swim Risk conditions may occur at all southern WI beaches
  Saturday night.

- Numerous thunderstorms, possibly severe, are forecast Monday
  and Monday night.


&&

.SHORT TERM...
Issued 1134 PM CDT Fri Jul 17 2026

Tonight through Sunday night:

The CAMs continue to dissipate the current MCS over west
central WI over the next 2-3 hours but will still have at least
slight chance PoPs as a wly 850 mb jet of 30 kts and thermal
ridge shifts swd into the area just ahead of the approaching
cold front. PWATs will increase to 1.6-1.9 inches during the
overnight with elevated CAPE of 2000 J/KG expected. The CIN will
be weak but so is the forcing. The cold front will track from
nw-se across the area from 10-16Z with a continued possibility
for development as it moves toward the IL border. Sfc based
convection may become possible toward the border by late
morning, but much of the expected storm development will be in
nrn IL in the afternoon.

Nly winds and weak cold advection will then settle over srn WI
for the afternoon including a lake breeze boosted by the front.
High temps in the middle to upper 80s will likely be reached by
noon over far ern WI before cooler lake air moves inland. Heat
index values on Sat will range from the upper 80s north of I-94
to the lower 90s south. High pressure will then settle over the
nrn Great Lakes and nrn WI Sat nt, then moving to lower MI and
Lake Huron on Sun. Cooler low temps in the lower to middle 60s
is forecast Sat nt with highs Sun in the upper 70s to lower 80s.
The high temp forecast for Sun is accounting for fairly
widespread smoke that will arrive Sat nt and continue through
Sun.

Gehring

&&

.LONG TERM...
Issued 1134 PM CDT Fri Jul 17 2026

Monday through Friday:

For Mon-Mon nt a couple upper waves over Canada will support a
996 mb low across nrn Ontario. A wly low level jet of 30-40 kt
and associated thetae advection will arrive on Mon with fairly
widespread showers and storms expected. The cold front and the
srn periphery of the shortwave trough will follow Mon nt, but
there is uncertainty if the warm front will pass or stall over
sw WI or farther west due to the earlier storms and clouds.
Nevertheless the baroclinic zone and CAPE gradient will likely
be sufficiently close for a additional storms and severe
potential over some of the area. Afterward nwly winds and cold
advection will prevail on Tue but with temps still near normal.
Nwly flow aloft and high pressure gradually moving from the
Upper MS River Valley to the Mid Atlantic States is the trend
for the remainder of the week. Little to no chances for rain
with temps near normal.


Gehring

&&

.AVIATION...
Issued 1134 PM CDT Fri Jul 17 2026

VFR conditions tnt-Sat but with low chances for showers and
thunderstorms early Sat AM into early Sat PM. Sct-bkn040-060
expected during this period. Areas to possibly widespread smoke
will then move into srn WI late Sat afternoon through the
evening and continue well into Sunday. Vsbys may fall to 1-2SM
with the smoke with areas of Cigs of 2-3kft.

Gehring

&&

.MARINE...
Issued 1134 PM CDT Fri Jul 17 2026

Areas of smoke will continue over the north half of the lake
tonight. Otherwise breezy southwest to west winds will develop
ahead of a cold front. The low pressure area around 29.7 inches
will track from just north of Lake Superior tonight across
southern Quebec Saturday afternoon and deepen to 29.4 inches. Its
trailing cold front will track from northern Lake Michigan
Saturday morning to far southern Lake Michigan by early afternoon.
Smoke will return to Lake Michigan behind the cold front and may
become dense once again. Breezy northerly winds are forecast
behind the cold front and will linger into Saturday evening.

Winds then quickly taper Saturday night, as high pressure around
30.1 inches moves over the northern Great Lakes. Northeast to
light and variable winds are then expected through Sunday into
Sunday night. Gusty south to southwest winds may then develop
Monday into Monday night, with gusty west to northwest winds
possible into the middle of next week.

A Small Craft Advisory will likely be needed Sat nt from
Sheboygan to Winthrop Harbor due to breezy northeast winds and
building waves.

Gehring

&&

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

$$

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