NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 111637
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1137 AM CDT Sat Jul 11 2026

.KEY MESSAGES...

- Hot temperatures will return early next 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.

&&

.SHORT TERM...
Issued 1137 AM CDT Sat Jul 11 2026

Tonight through Sunday night:

Surface high pressure overhead today will strengthen a bit more
tonight into Sunday, while a strong upper level ridge builds in
from the west. Scattered cumulus clouds are possible away from
Lake Michigan this afternoon, but otherwise mostly clear skies
are likely through tomorrow. Patchy river valley fog will be
possible again later tonight into early Sunday under mostly
clear skies and light winds. Temperatures will warm up a bit
more tomorrow with highs into the upper 80s, though temps will
be just a bit cooler near the lake under onshore winds.

DDV

&&

.LONG TERM...
Issued 1137 AM CDT Sat Jul 11 2026

Monday through Saturday:

Surface high pressure and the upper ridge are expected to
remain in place Sunday through Tuesday, with the ridge gradually
flattening mid to late week while the surface high weakens.
Temperatures will continue to warm up early week under the
strong upper ridge. Models have been trending upwards with high
temps Monday-Wednesday, with 925 mb temps in the 26-30C range
during this period. Given plenty of sunshine and relatively
light winds these days, bumped highs up to the low to mid 90s.
There is the potential for some upper 90s to around 100 if the
forecast 925 mb temps hold. Could also see these higher end
temps if the dewpoints end up a bit lower than anticipated.
While the GFS remains a bit cooler (as it does sometimes during
hotter stretches), the ECMWF and Canadian ensemble probabilities
for temps of 90+ are in the 90 to 100 percent range, especially
Monday and Tuesday. The latest RRFS is also showing high temps
well into the 90s Mon and Tue.

Still think dewpoints should be a bit lower than the last hot
stretch, maxing out in the upper 60s to low 70s. There is a
fairly wide spread among models with the dewpoint forecast Mon-
Wed, ranging from mixing out to the upper 50s/low 60s to locked
in the mid-70s. Winds will generally be light out of the west
Mon-Wed under the high, so there won't be strong low level
advection of higher dewpoints. With maturing crops though,
evapotranspiration could add a meaningful amount of moisture to
the low levels. The dewpoints will play a significant role with
how high heat indices end up, leading to some uncertainty with
heat headline potential. Went with dewpoints down the middle of
potential solutions for now, which is leading to forecast heat
indices in the upper 90s to low 100s for at least Monday and
Tuesday.

As the ridge flattens later next week, temps should fall back
toward normal values. Additionally, the door will open back up
for shower/storm chances Thursday through Saturday as a
shortwave or two comes over top of the flattening ridge.

DDV

&&

.AVIATION...
Issued 1137 AM CDT Sat Jul 11 2026

Patchy river valley fog will be possible again tonight.
Otherwise, VFR conditions will persist with FEW to SCT diurnal
cumulus around 5 kft this afternoon away from Lake Michigan.
Mostly clear skies are likely tonight into Sunday. East to
northeast winds of 5 to 10 knots today will become light and
variable under high pressure for tonight and Sunday, except for
east to southeast winds 5-10 knots near Lake Michigan tomorrow.

DDV

&&

.MARINE...
Issued 1137 AM CDT Sat Jul 11 2026

High pressure of 30.1 inches over the Great Lakes today will
strengthen to 30.2 inches by Sunday morning. The high will
largely stay put through the first half of next week, eventually
weakening and shifting southward by late in the week ahead of
an approaching trough of low pressure. Northerly winds generally
under 15 knots through today will become southerly across the
north Sunday, while becoming light and variable in the south.
Winds will become southerly across the lake Monday, increasing a
bit by Tuesday.

DDV

&&

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

$$

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