NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 130004 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
704 PM CDT Sun Jul 12 2026

.KEY MESSAGES...

- Hot temperatures will return for at least the first half of
  the upcoming week, with highs in the low to mid 90s Monday
  through Wednesday. Heat indices may reach 100 at times.

- Dry weather is expected through Wednesday, with thunderstorm
  chances returning late in the week.

&&

.UPDATE...
Issued 703 PM CDT Sun Jul 12 2026

A robust line of storms developed in the U.P. and tracked
southward across the Door Peninsula and into northern Lower
Michigan as it weakened. Outflow from this decaying storm
complex is apparent on the Green Bay radar and could reach
Sheboygan around 9 pm if it does not dissipate. Winds would be
20 kt or less with no precip (and barely any clouds) based on
current trends. The meso model that had a handle on this was the
12Z WRF ARW. Most of the other CAMs favored the second round of
storms to be stronger as they crossed Lake Superior, but this
round diminished quickly.

Otherwise, expect quiet weather, calm winds, clear skies, and
lows in the mid to upper 60s across southern WI tonight.

Cronce

&&

.SHORT TERM...
Issued 1224 PM CDT Sun Jul 12 2026

Tonight through Wednesday:

Mostly clear skies are expected through tonight outside of a
few to scattered afternoon cumulus this afternoon. Patchy river
valley fog will be possible again later tonight into early
Monday under the clear skies and another round of light to calm
winds.

A strong upper level ridge will continue to build in from the
west today into Monday and then largely remain in place through
at least mid-week. Surface high pressure will be overhead
through Tuesday as well, weakening a bit Wednesday as low
pressure passes by well to the northeast. A stretch of hot
weather is thus still expected with this pattern in place Mon-
Wed, with highs in the low to mid 90s and heat indices possibly
cracking 100 at times.

Dewpoints and resultant head indices continue to be the
forecast focus for the next few days, as it will be a battle
between afternoon mixing lowering dewpoints and moisture from
maturing crops potentially bumping dewpoints up a bit. Over the
last couple days, dewpoints have trended toward the lower end of
model guidance. As the high sits overhead for a couple days
though, there is the possibility that dewpoints wind up a bit
higher each day. Additionally, there could be some pooling of
higher dewpoints along and ahead of the low level boundary
arriving from the northeast on Wednesday, between the high
sagging to the south and the low passing by well to the
northeast. For now, stayed largely down the middle of model
guidance for dewpoints through Wed given the lingering
uncertainty. This would result in heat indices towards the 100
degree mark Mon- Wed, with the best chance to top 100 on
Tuesday. If dewpoints continue toward the lower end of guidance
the next couple days, temps would likely wind up a bit higher
than currently forecast. The lower dewpoints would likely
balance the higher temps though, keeping heat indices near
current expectations.

Based on expected heat indices of 95-100 tomorrow, the current
plan is to hold off on a Heat Advisory. We'll see how dewpoints
fair today and again Monday and then assess the potential for
an advisory Tue and/or Wed.

DDV

&&

.LONG TERM...
Issued 1224 PM CDT Sun Jul 12 2026

Thursday through Sunday:

Latest model trends hold onto upper level ridge across the
Plains and into the Midwest into the second half of the week.
The GFS continues to show a troughing pattern digging a bit
more southwest into the Great Lakes, but the ECMWF and
Canadian solutions suggest the ridge will be the more dominant
feature for southern Wisconsin during this time. The latest
ECMWF and Canadian ensemble average high temps for Madison are
in the low to mid 90s through Friday. Given the overall trend
towards a more stubborn ridge, forecast temps Thursday into the
weekend are gradually on the rise. A stronger ridge would also
delay the return of shower/storm chances until possibly as late
as next weekend, with the latest forecast now dry on Thursday,
with just low end chances on Friday. By Sunday, models are in
decent agreement that a shortwave and cooler conditions should
arrive in the area along with a chance for showers and storms.

DDV

&&

.AVIATION...
Issued 703 PM CDT Sun Jul 12 2026

Overall, expect clear skies and nearly calm winds that favor a
westerly direction tonight. A few high clouds are possible
toward Lake Michigan. I added a tempo group for a brief wind
direction shift at Sheboygan if outflow from decaying storms
over northern Lake Michigan makes it there (between 01 and 02Z).
Look for westerly winds up to 10 kt Monday with mostly sunny
skies. A lake breeze will remain close to the shoreline, but
could make it to KMKE by late afternoon.

Cronce

&&

.MARINE...
Issued 1224 PM CDT Sun Jul 12 2026

High pressure of 30.2 inches over the Great Lakes region will
maintain an axis roughly from northern Iowa to southern Lower
Michigan through Monday and then sink into Illinois and Indiana
Tuesday and Wednesday while weakening to 30.1 inches. Low
pressure around 29.6 inches will approach from the Northern
Plains Thursday into Friday. Southerly winds across the northern
half of the lake will continue today along with light and
variable winds south. Winds will then become south-
southwesterly for Monday and Tuesday. A weak cold front will
bring a wind shift to the north- northeast Wednesday into
Thursday.

DDV

&&

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

$$

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