NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 061859
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
159 PM CDT Mon Jul 6 2026

.KEY MESSAGES...

- Areas of fog possible west of Madison overnight, with dense
  fog in the Wisconsin River Valley.

- Dry conditions with warm but near normal temperatures with
  high pressure for today into Tuesday.

- Shower and thunderstorm chances increase Wednesday night into
  Thursday evening.

&&

.SHORT TERM...
Issued 159 PM CDT Mon Jul 6 2026

Tonight through Wednesday:

The steady northeast winds will diminish quickly this evening
and become light and variable through Tuesday night as high
pressure moves overhead. Expect a lake breeze on Tuesday. Any
line of storms that approaches from the Northern Plains tonight
is expected to diminish by the time it reaches south central
WI. The main weather concern is the fog potential for tonight.

Our current dewpoints range from the lower 50s in east central
WI to the mid 60s at Lone Rock. Looking back at obs from last
night, the area under the surface ridge over Iowa had areas of
fog, locally dense. That area will be over southwest WI tonight.
With clear skies, light winds and dewpoints of around 60 and
min temps similar, patchy fog makes sense from Madison to
Janesville and west. Dense fog is likely in the Wisconsin River
Valley and possible for the Rock River valley. Eastern WI areas
will have the lower dewpoints so not expecting fog there.

We will see mid 50s to around 60 for lows tonight. Tuesday
highs will range from the mid- upper 80s toward Wisconsin Dells
to just shy of 80 along the lakeshore. Expect more widespread
diurnal cumulus clouds than what we saw today.

Cronce

&&

.LONG TERM...
Issued 159 PM CDT Mon Jul 6 2026

Wednesday night through Monday:

A slow-moving cold front and surface low pressure system coming
down into Wisconsin from the northwest Wednesday night could
create the potential for precipitation development. Surface
convergence and MUCAPE values over 1000J/kg, combined with
synoptic forcing on the right-entrance region of the upper-level
jet support the chance of showers and storms. Considerable
precipitable water values of 1.5-2" also favor showers and
storms across the region (50-70%) Wednesday night. Although these
factors contribute heavily, low deep layer shear could reduce the
risk of severe activity and significant MCS development.

Into Thursday morning and afternoon, the cold front could create
persistent chances for showers and storms (60-80%), with
continued instability providing potential for MCSs. Drier
conditions are expected to move through as the cold front
continues to move south and a surface high pressure system forms
over northern Ontario.

Through the weekend, drier conditions are anticipated to remain
over the Great Lakes region with temperatures staying steady in
the high 70s to low 80s range with northwesterly flow, with
temperatures increasing into the high 80s toward the end of the
weekend and to Monday.

Zawlocki/Cronce

&&

.AVIATION...
Issued 159 PM CDT Mon Jul 6 2026

Steady northeast winds will diminish quickly this evening and
become calm overnight as high pressure moves overhead. Expect
patchy fog to develop late tonight, including Madison and
Janesville. A general 2 to 4SM vsby is likely, with locally
dense fog possible in river valleys and other low spots.
Not expecting fog in southeast WI due to drier air in place.

Diurnal cumulus clouds Tuesday morning may begin as MVFR but
then quickly increase to VFR by late morning. With light and
variable winds across southern WI Tuesday, expect a weak lake
breeze to develop by mid morning to track into Waukesha early in
the afternoon.

Cronce

&&

.MARINE...
Issued 159 PM CDT Mon Jul 6 2026

High pressure around 30.1 inches will remain in place over the
Upper Great Lakes through Tuesday. Expect steady north to
northeast winds through this evening, with light and variable
winds later tonight into Tuesday. Southwest winds will increase
Tuesday night and become gusty on Wednesday as weak low pressure
around 29.8 inches and an accompanying cold front approaches
from the Northern Plains. Winds will become northerly behind the
frontal passage Thursday afternoon into Friday, with high
pressure around 30.1 inches building into the the Upper Great
Lakes Region through the end of the week.

Cronce

&&

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

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, X, and YouTube at:
www.facebook.com/NWSMilwaukee
www.x.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee