NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 160034
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
734 PM CDT Sat Aug 15 2026

.KEY MESSAGES...

- Drizzle & a few pop-up showers through early evening

- Widely scattered showers & thunderstorms possible after
  midnight, though many locations will remain dry. No severe
  weather expected.

- Drier & more comfortable Monday. Storm chances return Tuesday
  into Wednesday.


&&

.UPDATE...
Issued 734 PM CDT Sat Aug 15 2026

Scattered to isolated rain showers have developed along and north of
a warm front currently moving northeast through Wisconsin. As these
showers bubble up on satellite and radar there have been a few
outflow boundaries that generated additional showers. This trend is
expected to continue until the warm front moves out of southern
Wisconsin.

The next chances for rain will likely hold off until the cold front
passes tonight. There are already rain and storms firing across
Minnesota and Iowa with this frontal boundary. Confidence is low on
any widespread rain and storms with the passage of the cold front.
The better upper level forcing looks to remain just to our south in
Illinois. Lowered POPs across the board for late this evening into
Sunday morning. The best chances for any rain will be along the
WI/IL border(30-40%). Can't rule out a few isolated showers for
areas further north, but chance are low around (10-25%). Hard to
have much of any confidence in this zonal setup where the placement
of the upper level PVA literally gives you feast or famine. Other
than the meager rain chances not much has changed in the
forecast.

Patterson

&&

.SHORT TERM...
Issued 253 PM CDT Sat Aug 15 2026

This Afternoon through Sunday:

Synopsis/Mesoanalysis: Busy pattern is apparent regionally this
afternoon, with a number of features impacting current & short term
weather conditions. Low pressure continues to migrate east toward
the International Falls, MN vicinity, with an attendant warm front
branching to its south and east. Said front has made it into far
southern Wisconsin, with current obs placing the feature along an
approximate Monroe - Edgerton - Burlington line. While temp/dew
point differences are minimal across the boundary, surface
convergence has been sufficient enough for widely scattered shower
development near & north of the front. Best radar returns have been
in southeast Wisconsin, where warm frontal convergence is being
further augmented by the lake breeze. Anticipate that this trend
will continue through the immediate near-term, but will need to
monitor for expansions in coverage as the boundary attempts to work
northward through early evening. Not expecting severe weather
hazards in any pop-ups. The International Falls surface low will
continue to work east tonight, dragging a cold front through
southern Wisconsin in the process. Additional scattered, non-severe
storm development is possible as the front moves through, though
many locations will remain dry. The front will shift east of the
area on Sunday, bringing a drier and more comfortable air mass to
most during the afternoon hours.

This Afternoon through Tonight: Beach Hazards Statement continues
through 7 PM at Milwaukee, Ozaukee and Sheboygan County beaches due
to elevated and breaking waves. Use extreme caution if heading
lakeside. Will be monitoring pop-up shower activity through ~7 PM,
in addition to potential widely scattered showers/storms along the
encroaching cold front near/after midnight. Not anticipating severe
weather hazards in any activity, though there will be just enough
instability around to support a few flashes of lightning. Move
indoors if thunder approaches your location. Given the overnight
arrival timing of the cold front, anticipating widely scattered
coverage in any post-midnight precip, with many locations staying
dry through the frontal passage.

Quigley

&&

.LONG TERM...
Issued 253 PM CDT Sat Aug 15 2026

Sunday Night through Saturday:

Synopsis: Drier air will lead to pleasant and comfortable conditions
on Monday afternoon. Moisture will gradually work back into southern
Wisconsin Tuesday through Wednesday, leading to muggier conditions.
A cold front will swing through the western Great Lakes Tuesday
evening into Wednesday, triggering the next round of shower and
thunderstorm development as it impinges upon the returning humid air
mass. Tuesday evening & night currently appears to be most favored
for storms in southern Wisconsin. Broader ingredients will be in
place for a few stronger storms with heavy downpours, though where
exactly those ingredients come together best remains uncertain. Will
continue to monitor trends. If the front lingers across the region
long enough, additional storm development would be possible on
Wednesday afternoon. Passing high pressure and drier air will lead
to pleasant & largely precip-free conditions through the end of the
week. An isolated shower is possible on Friday as broad warm
advection spreads over the Upper Midwest, though confidence in
occurrence, timing, and placement is low at this time.

Tuesday Evening into Wednesday: Continue to anticipate a window of
storm potential along a passing cold front. Global deterministic &
ensemble guidance remains in sound agreement regarding an
evening/overnight frontal passage, which continues to point toward
this time frame as being the most likely to see storm development.
Given the model agreement, continue to maintain precip probabilities
from the NBM, which maximize (~75+%) during the ~7 PM Tuesday - 7 AM
Wednesday time frame. Favorable positioning of a seasonably strong
upper jet/attendant wind shear over the Upper Mississippi Valley
points toward organized storm potential, though where exactly the
best moisture/instability overlap with the favorable dynamics
remains to be seen. Global ensembles currently depict southern
Wisconsin on the northeast side of an instability plume centered
over Iowa, which if verified would generally place the highest
severe potential from the western half of the CWA back westward. Any
changes in frontal timing, however, would lead to shifts in the
instability plume and zone(s) of greatest severe potential.
Seasonably moist conditions will be supportive for heavy downpours,
though whether enough storms and/or training occurs to support a
flooding threat remains to be seen. Will thus be monitoring trends
regarding the aforementioned uncertainties over the next couple
days.

Quigley

&&

.AVIATION...
Issued 734 PM CDT Sat Aug 15 2026

VFR to IFR conditions are expected through the period. Flight
categories are expected to vary into tonight. Ceiling heights and
potential rain will be the main drivers for lower flight categories.
The VFR to MVFR ceilings around 2-7 kft are expected to become more
uniform with time and gradually fall to around 500 to 2000 ft. Rain
showers have developed across portions of central and east central
Wisconsin this evening and should slowly move northeast with time.
Under pockets of low ceilings drizzle will be possible as well.
There is uncertainty in who receives drizzle and who does not.
Additional chances for rain and a few thunderstorms will be possible
with the passage of a cold front tonight. The best chances for rain
are expected to be along the WI/IL border. Restricted PROB 30s to
the most likely times for showers and storms and shortened windows
for storms considerably for terminals along I-94. Visibilities are
expected to range from 4-6 SM with any rain or drizzle. The low
ceilings are expected to linger into Sunday morning and then should
gradually improve back to VFR conditions.

Variable southerly winds will persist into tonight before shift to
northwesterly Sunday morning. Northwest winds may become breezy at
times Sunday afternoon before becoming light and variable Sunday
night.

Patterson

&&

.MARINE...
Issued 253 PM CDT Sat Aug 15 2026

1023 mb high pressure is centered near the Saint Lawrence River this
afternoon, resulting in generally light easterly winds across the
open waters. The high will progress into the northeastern United
States tonight as a cold front approaches from the northern Great
Plains, resulting in a brief period of south-southeasterly winds
this afternoon and tonight. The aforementioned surface front will
move across Lake Michigan early Sunday morning, with northwest winds
becoming established by Sunday afternoon across the entirety of the
lake. Periods of scattered showers and thunderstorms continue today
into Sunday morning ahead of the front. Severe weather is not
anticipated.

A new area of 1018 mb high pressure will build in from the northern
Great Plains late Sunday night into Monday, bringing light and
variable winds to the waters through the majority of Monday and
Monday evening. A slow-moving cold front will approach from the
northern Great Plains Tuesday into Wednesday, bringing increasing
southwest winds and chances for thunderstorms. Precise timing
details will continue to be refined over coming forecasts, though it
does appear that a few stronger storms could be possible over the
southern half of the waters Tuesday afternoon & night. Winds will
trend light and variable behind the front from Wednesday night
through the end of next week.

Small Craft Advisory conditions continue north of North Point
Lighthouse through 7 PM CDT this evening. Chances for showers &
isolated thunderstorms continue into Sunday along/ahead of a passing
cold front, with severe weather impacts not expected. The next
chances for thunderstorms arrive Tuesday afternoon into Wednesday.
Precise timing details will become clearer in coming forecasts,
though it does appear that a few stronger storms could be possible
in this activity. Will be monitoring trends closely over the next
couple days.

Quigley

&&

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

$$

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