NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 310610
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
110 AM CDT Fri Jul 31 2026

.KEY MESSAGES...

- Widespread showers will spread west to east today, continuing
  across the region through Saturday. Isolated thunderstorms are
  possible, especially south of I-94.

- Probabilities of over 1 inch of rainfall are moderate to high
  (over 60%) along and south of I-94, while probabilities of
  over 2 inches are moderate (over 40%) in southwestern
  Wisconsin. Flooding or severe storms is not currently
  expected.

- Breezy onshore winds will lead to high waves and dangerous
  currents at Lake Michigan beaches this weekend. A Beach
  Hazards Statement is in effect from late tonight through
  Sunday night for all Lake Michigan beaches.

- Next chances for thunderstorms Tuesday night into Wednesday.

&&

.SHORT TERM...
Issued 111 AM CDT Fri Jul 31 2026

Today through Saturday night:

With low pressure deepening in the central Plains and PWATs of
1.5-2 inches progressing eastward into the Upper Midwest today,
anticipating the drier airmass that may serve as an inhibiting
factor for rainfall to stay across central to northern Wisconsin,
allowing for a steady rain to progress through southern Wisconsin
starting midday today. A few periods of thunder may be possible,
especially south of I-94, as low pressure makes its approach
through central Iowa this afternoon. However, elevated instability
around 100-500 J/kg and stronger convection across Illinois may
allow for isolated lightning even outside of storm development in
the stratiform region. Expecting highs in the mid 70s to low 80s
ahead of rainfall.

Steady rain is expected to continue through the overnight hours
tonight along and south of I-94, with the lightning threat
diminishing after sunset as low pressure sinks farther south and
continues to occlude, putting southern Wisconsin firmly within the
cold conveyer belt on the northern side of the low. Areas north of
I-94 are expected to see more showery activity rather than steady
rainfall. PWATs remain in the 1.5-2 inch range, with warm cloud
layers as deep as 14,000 ft. This may lead to very efficient rain
production even without convective development. A few convective
allowing models are calling for isolated pockets of rainfall up to
5 inches over today and tonight, but these accumulations will
depend on exactly where multiple rounds of rainfall train, and if
no training segments develop most areas will see 1-2 inches total.
Probabilities of over 1 inch are moderate to high (over 60%)
along and south of I-94, while probabilities of over 2 inches are
moderate (over 40%) in southwestern Wisconsin near the center of
the low track.

Saturday, although low pressure will occlude and progress eastward
into the Ohio Valley, wrap-around shower activity will continue
through much of the day. Still not anticipating much thunder with
this activity as the atmosphere remains stable in the cold air
portion of the low. PWATs remain high. With overcast skies,
expecting highs in the 70s. Northeasterly winds will continue to
gust around 30 mph through the day and into the overnight hours as
the low finishes occluding and stacking. Rainfall/showers will
finally taper off west to east into the evening as low pressure
slowly pivots southeastward, with PWATs falling below 1.5 inches
overnight. Overnight lows around 60 degrees are expected.

As the low approaches tonight, expect easterly winds to increase
to gust between 20 and 30 mph. As winds increase, onshore flow
will lead to high waves and dangerous currents along Lake Michigan
beaches. Winds turn northeastward into Saturday as low pressure
exits into the Ohio Valley, but will continue to increase to gust
30 to 35 mph. A High Swim Risk is expected late tonight through
Sunday as low pressure lingers over the Ohio Valley and
northeasterly winds continue. A Beach Hazards Statement is in
effect. Stay out of the water and away from dangerous areas like
piers and breakwalls!

MH

&&

.LONG TERM...
Issued 111 AM CDT Fri Jul 31 2026

Sunday through Friday:

High swim risk continues into Sunday. Expect continued
northeasterly winds gusting 20-30 mph as low pressure slowly
exits. No precipitation is expected, with highs in the mid to
upper 70s. High pressure builds in Sunday night into Monday,
bringing light and variable winds and temperatures in the low 80s
for Monday.

Low pressure develops in the central Plains Tuesday, with a
shortwave over Ontario showing potential for phasing with this
low, and bringing the next chances for precipitation to southern
Wisconsin Tuesday night through Wednesday as the resultant system
propagates eastward (20-30%). Highs in the low to mid 80s are
expected both Tuesday and Wednesday.

Active pattern persists through Friday, with multiple shortwaves
developing off the northern portions of the central Plains low.
Uncertainty remains in the longer term portion of the forecast as
model solutions diverge, therefore kept NBM PoPs in the 15-25%
range Thursday and Friday.

MH

&&

.AVIATION...
Issued 111 AM CDT Fri Jul 31 2026

VFR conditions and light and variable winds into this morning,
with winds becoming southeasterly and steady by the afternoon
hours. Winds continue to shift to become northeasterly overnight,
increasing to gust 20-25 kt through Saturday morning.

Widespread showers are expected to spread west to east through
southern Wisconsin midday through this evening, continuing
throughout the overnight hours. Expect MVFR visibilities within
the showers, with ceilings gradually lowering to MVFR then down to
1000 ft overnight into early Saturday morning. Low ceilings and
showers persist into Saturday morning.

MH

&&

.MARINE...
Issued 111 AM CDT Fri Jul 31 2026

High pressure around 30.0 inches will linger over Lake Michigan
through this morning, with low pressure over the central Plains
deepening to 29.6 inches as it moves into eastern Iowa this
evening. This will shift winds to easterly overnight tonight.
Saturday, expect winds to shift to northeasterly as low pressure
moves into the Ohio Valley and deepens to 29.5 inches. Gusts to 30
kt are expected Saturday afternoon through Sunday afternoon for
the southern two-thirds. An isolated gale is possible Sunday
afternoon as low pressure lifts into Michigan. A Small Craft
Advisory is in effect for southern Wisconsin nearshore zones from
late tonight into Sunday night due to gusty winds and building
waves. Low pressure will finally exit into Sunday night with
winds diminishing into Monday. High pressure returns Monday into
Tuesday, bringing light and variable winds. Tuesday night into
Wednesday, southerly winds become dominant as a low pressure
system develops in the Plains.

MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-
     WIZ072...4 AM Saturday to 1 AM Monday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...4 AM
     Saturday to 1 AM Monday.

&&

$$

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