NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 031140
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
640 AM CDT Mon Aug 3 2026

.KEY MESSAGES...

- Patchy fog ending in low lying areas this morning.

- Next chances for thunderstorms Tuesday night through Wednesday
  night. Multiple rounds of storms may lead to local flooding. A
  few periods of strong storms cannot be ruled out, but timing
  and impacts are not yet clear.

&&

.UPDATE...
Issued 639 AM CDT Mon Aug 3 2026

Patchy fog in low lying areas ending by 8 or 9 AM. The surface
ridge over WI will slowly shift ewd later today and tnt,
reaching the Lower Great Lakes by 12Z Tue. High temps will range
from the middle 70s near the lake to lower 80s inland.

Gehring

&&

.SHORT TERM...
Issued 107 AM CDT Mon Aug 3 2026

Today through Tuesday night:

Moderate swim risk continues through early this morning for Milwaukee,
Racine, and Kenosha County Lake Michigan beaches. Stay away
from dangerous areas such as piers and breakwalls.

Temperatures falling into the upper 50s and low 60s this morning
with dewpoint temperatures in the low 60s will lead to fog
development in river valleys, as well as patchy fog development in
southwestern Wisconsin under clear skies and calm winds. Fog will
burn off an hour or so after sunrise, with mostly clear skies
(diurnal cumulus) and temperatures in the upper 70s to low 80s
expected for the rest of the day.

High pressure lingers overnight tonight, with lows around 60
degrees. Patchy fog is possible, but less likely overnight tonight
as winds will remain light and southerly through the overnight
hours. Cloud cover will also slowly increase through the overnight
hours.

Winds will become steady and southwesterly into Tuesday, bringing
in warmer temperatures ahead of a weak frontal boundary moving
southward through northern Wisconsin during the afternoon hours.
Expect highs in the mid-80s. Isolated to scattered showers and
thunderstorms (20-30% coverage) look to develop as MUCAPE of
1000-1500 J/kg and PWATs of 1.5-1.75 inches build into southern
Wisconsin ahead of the front. The front will gradually sink
southward through the overnight hours, bringing more widespread
rain and storms. MUCAPE around 1000 J/kg lingers through the
overnight hours, with bulk shear building to 40-45 kt. A very
strong stable layer near the ground and shear parallel to the
front will likely keep storms sub-severe. However, widespread
rainfall is expected (60-80% PoPs). With high PWATs, instability
along the front, warm cloud layers up to 14,000 ft, and the
potential for multiple rounds of storms, localized flooding may
become possible.

MH

&&

.LONG TERM...
Issued 107 AM CDT Mon Aug 3 2026

Wednesday through Monday:

Storms linger into Wednesday as low pressure ejects from the
central Plains into the Middle Mississippi Valley. With southern
Wisconsin remaining on the north side of the low and overrunning
precipitation from the night before, expecting benign rainfall
through the morning hours. If clearing develops early enough in
the day, instability may work back into southern Wisconsin for
Wednesday afternoon and evening, setting the stage for potential
severe weather. MUCAPE up to 2000 J/kg is shown on some ensemble
members of GFS and Euro, but will be highly dependent on clearing
after early morning showers and storms. Shear remains favorable
throughout the day (45-50 kt bulk shear values), with afternoon
storms likely forming on the northern edge of upper level ridging
and moving eastward, leading to perpendicular shear vectors and a
ridge-rider setup. Storms finally exit to the east into Thursday
morning, with clearing skies and highs around 80 degrees.

Thursday night, high pressure builds back into the western Great
Lakes, bringing light winds, lows in the upper 50s to low 60s.
High pressure lingers through Friday and Friday night with highs
in the low to mid 80s. Saturday and Sunday, low pressure
developing in the northern Plains will bring strong southwesterly
winds and temperatures in the mid-80s all the way to Lake
Michigan. A return to showers and storms Sunday through Monday as
a frontal boundary from the low moves southward through Wisconsin,
although confidence in timing and impacts remain uncertain at this
time (15-25% PoPs).

MH

&&

.AVIATION...
Issued 639 AM CDT Mon Aug 3 2026

Patchy fog through 8 or 9 AM, then VFR conditions today and tnt.

Gehring

&&

.MARINE...
Issued 107 AM CDT Mon Aug 3 2026

Low pressure around 29.7 inches will continue to lift
northeastward through southeastern Ontario into southern Quebec
today, with high pressure around 30.0 inches building into the
western Great Lakes. Northerly winds this morning will diminish to
light and variable today through tonight. Winds become
southwesterly and increase on Tuesday as low pressure of 29.4
inches develops over the Hudson Bay. A cold front from this low
will progress southward through the Lake Tuesday night through
Wednesday, bringing chances for thunderstorms. Easterly winds are
expected north of the front, with southerly winds south of the
front. The front will stall through Wednesday night, finally
pushing southward into Thursday. Winds will become light and
variable again under high pressure as the front exits, before
shifting to southerly again into Friday.

MH

&&

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

$$

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