NWS-Milwaukee/Sullivan Forecast Discussion
FXUS63 KMKX 292327
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
627 PM CDT Sat Aug 29 2026
.KEY MESSAGES...
- Brief break in showers across the area early this evening,
with more activity filling in near/after 9 PM.
- Becoming very warm and humid Sunday and persisting much of
next week. There will be storm chances at times through at
least the first half of next week.
- A Small Craft Advisory may be needed late tonight into Sunday
morning, particularly north of North Point Lighthouse. A Beach
Hazard Statement may also be needed for Sheboygan and Ozaukee
Counties.
&&
.UPDATE...
Issued 625 PM CDT Sat Aug 29 2026
Tied to an impulse at the 500 mb level, afternoon rain showers
are departing over Lake Michigan early this evening. Departure
of the feature, in addition to subsidence evident in satellite
imagery in its wake, will keep the area rain-free through at
least the first half of the evening hours. Expecting this lull
to be short-lived, however, as broad warm advection increases
regionally into tonight, This will lead to additional shower
development with a few rumbles of thunder. Beginnings of this
activity have been observed in radar mosaics from Rochester,
MN southeast toward the Quad Cities, with rough timing estimates
showing the leading edge of precip potential reaching western
areas near/after 9 PM. Anticipate that activity will continue
east across the remainder of the area through the first half of
the overnight. Steadily warming temperatures in the 850-700 mb
layer will be moving in from the Northern Plains along with
showers, so some questions remain whether precip will eventually
be suppressed during the second half of tonight or if it will
linger in the presence of the low level jet. Will be monitoring
trends & making forecast adjustments where necessary. Not
anticipating hazards in any embedded thunder.
Quigley
&&
.SHORT TERM...
Issued 221 CDT Sat Aug 29 2026
Tonight through Sunday night:
Waves of scattered light to moderate rain have pushed into
southern Wisconsin through the late morning and into the
afternoon today. While most rain is reaching the ground, it has
struggled to stay organized as the rain has run into a
retreating surface ridge and dry air at the surface. More
shower activity will work through Southern Wisconsin through
the rest of the afternoon and into the early evening, riding the
leading edge of low to mid- level WAA into the Upper
Mississippi Valley.
There may then be a brief lull in the rain this evening, before
the LLJ broadens and strengthens overnight into Sunday morning.
Scattered showers and a few rumbles of thunder should blossom
before dawn over east central and southeast WI and then
continue into the daytime hours of Sunday morning. It won't be a
washout, but scattered shower and thunderstorm activity should
then continue through the daytime hours. MUCAPE is expected to
reach around 1000 j/kg over southern WI and especially near the
WI/IL border, but CAPE profiles will be skinny, with high
freezing levels. Any storms tomorrow also look to be fairly high
based with an inverted v signature in the low levels. As such,
any stronger storms may have some isolated small hail, if any,
and gusty winds. Severe weather is not anticipated at this time.
After another brief break after sunset Sunday evening, more warm
advection driven showers and storms may form early Monday
morning along the Wisconsin and Illinois border
Elevated southerly winds may cause moderate risk conditions at
beaches in Sheboygan and Ozaukee Counties. For now, surf zone
waves look to stay at 3 feet which just below beach hazard
criteria. Trends in wave heights will be watched through
subsequent model runs for a potential Beach Hazard Statement.
CMiller
&&
.LONG TERM...
Issued CDT Sat Aug 29 2026
Monday through Saturday:
A warm, humid, and active weather pattern is expected this
upcoming week, following the progression of a warm front
northward on Sunday and then a slow progression southward of a
stationary/cold front Monday through the late week. With the
front present there will be daily chances for scattered showers
and storms as weak waves propagate along the boundary. However,
it is not expected to be a washout. Strong to severe storms may
occur at times, especially midweek as better shear overlaps
with the frontal boundary.
Heat and humidity are expected with highs near 90 Monday through
Wednesday and dewpoints in the low 70s. Temps may "cool" late-week
as the front sags southward over the area, but
shower/thunderstorm chances may continue into the beginning of
next weekend.
CMiller
&&
.AVIATION...
Issued 625 PM CDT Sat Aug 29 2026
Afternoon showers are departing southern Wisconsin, with a lull
anticipated through the first half of the evening hours.
Anticipating a gradual fill-in of activity during the second
half of the evening, with precip moving west to east into the
first half of the overnight hours. Whether activity lingers into
the predawn hours or moves entirely east of the area remains
uncertain, with trends being monitored through this evening.
Will be adjusting near-term PROB30 groups at all terminals
given anticipated evolution of showers & lingering
uncertainties.
A low level jet will also move overhead tonight, causing
southwest wind shear from 35 to 40 knots. Surface winds may
remain elevated overnight with continued gusts to 20 knots and a
more southwesterly surface wind direction.
Quigley/CMiller
&&
.MARINE...
Issued 236 PM CDT Sat Aug 29 2026
High pressure will continue to move east of the lower Great
Lakes into this evening, while low pressure deepens in the
central Great Plains tonight. This will support modest to breezy
southerly winds this afternoon through this evening. Tonight, a
warm front is expected to lift northward over the lake, and the
presence of a jet aloft may cause some gusty southerly winds to
30 knots over the south half of the Lake on Sunday.
Breezy southerlies then remain into Monday as the low will lift
northeast from the plains toward western Lake Superior. Scattered
thunderstorms will occur at times from tonight into next week. A
weak cold front will finally arrive late Tuesday night and
Wednesday with light northerly winds eventually taking hold.
CMiller
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&
$$
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