Severe Thunderstorm Warning 237, NWS Milwaukee, WI

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
637 AM CDT Sun Aug 9 2026

.KEY MESSAGES...

- Thunderstorm chances return today. There is the potential for
  a late morning to afternoon round, and then an evening round.
  Strong to severe storms will be possible. The evening round of
  storms may be the more conditional round of storms, depending
  upon if we can destabilize behind the morning round of storms.

- Any storms today will be capable of heavy rain. Localized
  flooding will be possible, especially where storms repeatedly
  track through the day.

- Periodic chances for showers and thunderstorms are possible through
  the first half of the week.

&&

.UPDATE...
Issued 626 AM CDT Sun Aug 9 2026

Weak convection on the leading edge of 850mb WAA has moved over
central WI this morning, causing scattered light to moderate
rain. Back in the better warm advection near the core of the
LLJ to our west, more robust convection has formed this morning,
with intermittent Severe Thunderstorm Warnings throughout the
night. Current SPC mesoA shows the strongest warm advection to
be occurring along the MS River Valley and further west over
Iowa.

The current thought is that the convection over Iowa should
track into our area by the mid to late morning with weaker
scattered showers and storms preceding this area of convection
in the meantime. The recent 09Z and 10Z runs of the HRRR want
to weaken this area of convection over southwest and south
central WI as the LLJ wanes in strength, before some
reinvigoration occurs near the Lake Michigan shoreline this
afternoon. This trend would mitigate more widespread flooding/severe
weather potential for today. But, convection currently looks
robust over Iowa. Radar and MesoA trends will be monitored as
this convection tracks toward southern WI this morning.

CMiller

&&

.SHORT TERM...
Issued 1240 AM CDT Sun Aug 9 2026

Today through Monday night:

Well... what an interesting hand we have been dealt today. Meso
models have started to converge on a scenario for this morning and
evening that favors a more robust round of morning convection with
weaker evening potential. This convergence of the meso models does
track well with the mid level and upper level shortwave and WAA.
With the synoptic forcing better aligned with guidance there is a
bit more confidence here, but for any MCS type system guidance will
never full grasp the full picture.

With storms starting to develop in in the Dakotas and western
Minnesota, this leaves us with one likely scenario with a few
contingencies. The likely outcome which favors models like the
FV3, Nam NEST, and HRRR has storms developing out west and
congealing into a n-s line that should move into southern
Wisconsin during the mid to late morning hours then exit to the
east during the early afternoon. The later timing does allow for
some instability to move into the area with good moisture, lift
and shear. Bulk shear remains around 40 kts or greater and the
LLJ keeps good WAA ahead of the line. This will therefore lead
to a stronger signal for strong to severe storms in the morning.
Now some guidance is far more robust with the instability than
others (HRRR could be considered a worst case scenario 00z run).
With more of a linear storm mode, this will open the door for
tornadic potential. Strong winds remain the larger hazard with
small hail possible. How much of a wind and tor threat this
becomes will entirely depend on the amount of instability we
have. The more instability the more widespread the severe risk
the less instability the more this is may a few downburst type
splats along the line.

With this later arrival time being favored, this looks to wash out
the window for an adequate afternoon recovery period. If that
is the case then the better instability gets shunted further
south into IL. This then favors an evening round beginning to
fire roughly along the WI/IL border or further south. The
uncertainty here in location still remains high. The mesoscale
environment will need to be watched closely as there are still
models that hint at the LLJ and strong WAA being able to
overcome that short window of time to bring storm chances back
north toward I-94. So were not completely out of the woods yet.
In the event that storms do develop in the evening along or
south of I-94, heavy rain will be the main concern. There could
be a few downburst winds in isolated areas, but PWATs will be
around 2 inches. The east to west orientation of the line
developing with corfidi vectors that indicate training
convection, means flooding will be a major concern where ever
this develops.

So TLDR is uncertainty does remain, but trends are highlighting
a more robust morning round of convection that lingers into the
afternoon. Then evening storms along the WI/IL border or
further south. If storms move through earlier in the morning and
are weaker, then the door is fully back open for evening storms
across southern Wisconsin. Stay up to date with the weather
today as the mesoscale environment will throw curve balls at
this scenario. Have a way to receive warnings.

Beyond this, we can look ahead to Monday which remains uncertain
(our favorite word of the week it seems). Under the zonal flow aloft
with multiple shortwaves and CAMs spitting out many solutions its
the name of the game. This time the question becomes where will
the sfc front end up and will it stay there. Its possible that
with todays activity (if it plays out how its trending), that
the sfc boundary remains just to our south and keeps with it the
better severe potential and flooding threats. If this front
remains stretched across southern Wisconsin or moves back north
into the area, then the warm (southern) side of the front will
be in play for severe and flooding, while the cooler (northern)
side of the front is spared from the worst of it. If the trends
hold, then much of the rain looks to stay in IL until Monday
evening/night.

Patterson

&&

.LONG TERM...
Issued 1240 AM CDT Sun Aug 9 2026

Tuesday - Saturday

A flattened upper-level cutoff low continues to meander around the
Hudson Bay region to our north on Tuesday. Given the persisting
pattern, could see another embedded shortwave trough round the base
of the longwave trough on Tuesday to bring additional shower and
thunderstorm chances to our neck of the woods as suggested by the
latest global models. Similar to the pattern for the next two days,
chances, strength, and location of this activity will depend on the
timing of the upper-level wave pairing with the low-level
front/instability gradient placement, which are subject to shift due
to prior days convection/pattern. Nevertheless, as multiple NCAR AI
NWP forecast ensembles suggests, the potential remains for some
storms for Tuesday.

Then for the midweek, we begin to see the upper-level low begin to
move east-southeast into Quebec shifting the more active pattern
further east. Northwesterly upper-level will to linger on the
backside of the departing trough and as a result looking at a drier
stretch for the second half of the week as the GEFS and EPS
ensembles become more aligned with the upper-level ridge
beginning to build across the northern Plains and into the Upper
Midwest into next weekend.

Temps in the extended are trending toward normal through the first
half of the week, but hints of near to even below normal temps
toward the end of the week.

Wagner

&&

.AVIATION...
Issued 636 AM CDT Sun Aug 9 2026

Clouds and thunderstorms will spread over the area over the
next few hours. A line of thunderstorms is expected to move
across the area from 15Z, onward into the mid afternoon. MVFR
ceilings will be possible with the storms, and some IFR may
occur over KSBM for a brief period around noon as the storms
pass overhead. Expect moderate southerly to southwesterly winds
today.

CMiller

&&

.MARINE...
Issued 1240 AM CDT Sun Aug 9 2026

Low pressure across the Hudson Bay will slowly move east toward
Maine today while a second low in the central Plains advances
east toward the southern Great Lakes Region. An unsettled weather
pattern will set up over the Upper Great Lakes all week where
weak waves of low pressure will cross the region and produce
rounds of thunderstorms at times. The firs round of storms
should arrive across the southern and central portion of the
lake late this morning into the afternoon. A second round of
storms is expected to develop across the southern third of the
lake this evening into tonight. Heavy rain will be possible with
each round of storms.

Southwest winds early this morning will become southerly by mid
to late morning and become breezy. Winds then become light and
variable across the lake tonight through Monday. Northeast to
east winds develop across the lake Tuesday and remain light.
Wind direction could become variable at times Tuesday.

Patterson

&&

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

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Hazardous Weather Outlook
National Weather Service Milwaukee/Sullivan WI
608 AM CDT Sun Aug 9 2026

WIZ046-047-051-052-056>060-062>072-101115-
Marquette-Green Lake-Fond du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
608 AM CDT Sun Aug 9 2026

This Hazardous Weather Outlook is for portions of east central
Wisconsin, south central Wisconsin and southeast Wisconsin.

.DAY ONE...Today and Tonight

A morning round of storms is expected followed by a potential
evening round of storms today. Some storms may be strong to
severe. Heavy rainfall is expected with localized flooding
possible mainly for the evening round potential.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Additional rain and storm chances persist through mid next week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed at times.

LMZ643>646-101115-
Sheboygan to Port Washington WI-
Port Washington to North Point Light WI-
North Point Light to Wind Point WI-
Wind Point WI to Winthrop Harbor IL-
608 AM CDT Sun Aug 9 2026

This Hazardous Weather Outlook is for the nearshore waters from
Sheboygan Wisconsin to Winthrop Harbor Illinois.

.DAY ONE...Today and Tonight

A morning round of storms is expected followed by a potential
evening round of storms today. Some storms may be strong to
severe. Heavy rainfall is expected, especially with the evening
round.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Additional rain and storm chances persist through mid next week.

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-101115-
Lake Michigan Michigan City IN to St. Joseph MI 5 NM offshore to
mid-line of lake.-
Lake Michigan from Seul Choix Point to Rock Island Passage 5NM
offshore to Mid Lake-
Lake Michigan South of a line from Seul Choix Point to the
Mackinac Bridge and North of a line from Charlevoix MI to South
Fox Island 5NM offshore-
Lake Michigan from Charlevoix to Point Betsie MI 5NM Offshore to
mid lake-
Lake Michigan from Point Betsie to Manistee MI 5NM offshore to
Mid Lake-
Lake Michigan from Rock Island Passage to Sturgeon Bay WI 5NM
offshore to mid lake-
Lake Michigan from Sturgeon Bay to Two Rivers WI 5NM offshore to
Mid Lake-
Lake Michigan from Two Rivers to Sheboygan WI 5NM offshore to Mid
Lake-
Lake Michigan from Sheboygan to Port Washington WI 5NM offshore
to Mid Lake-
Lake Michigan from Port Washington to North Point Light WI 5NM
offshore to Mid Lake-
Lake Michigan from North Point Light to Wind Point WI 5NM
offshore to Mid Lake-
Lake Michigan from Wind Point WI to Winthrop Harbor IL 5NM
offshore to Mid Lake-
Lake Michigan from Winthrop Harbor to Wilmette Harbor IL 5NM
offshore to Mid Lake-
Lake Michigan from Wilmette Harbor to Michigan City in 5NM
offshore to Mid Lake-
Lake Michigan from Pentwater to Manistee MI 5NM offshore to Mid
Lake-
Lake Michigan from Whitehall to Pentwater MI 5NM offshore to Mid
Lake-
Lake Michigan from Grand Haven to Whitehall MI 5NM offshore to
Mid Lake-
Lake Michigan from Holland to Grand Haven MI 5NM offshore to Mid
Lake-
Lake Michigan from South Haven to Holland MI 5NM offshore to Mid
lake-
Lake Michigan from St Joseph to South Haven MI 5NM offshore to
Mid Lake-
608 AM CDT Sun Aug 9 2026

This Hazardous Weather Outlook is for the open waters of Lake Michigan.

.DAY ONE...Today and Tonight

A late morning/afternoon and evening round of storms will be
possible over the southern two-thirds of Lake Michigan today.
Some storms may be strong to severe. Heavy rainfall is expected.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Additional rain and storm chances persist through mid next week.

www.weather.gov/mkx

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Special Weather Statement
National Weather Service Milwaukee/Sullivan WI
1003 AM CDT Sun Aug 9 2026

WIZ058-064-091600-
Dodge WI-Jefferson WI-
1003 AM CDT Sun Aug 9 2026

...STRONG THUNDERSTORMS WILL IMPACT JEFFERSON AND SOUTHERN DODGE
COUNTIES THROUGH 1100 AM CDT...

At 1003 AM CDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from near Fall River to near
Brooklyn. Movement was east at 30 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Watertown, Whitewater, Hartford, Fort Atkinson, Jefferson, Lake
Mills, Waterloo, Juneau, Johnson Creek, Palmyra, Hustisford, Lake
Ripley, Lake Koshkonong, Ixonia, Rome, Ashippun, Rubicon, Lebanon,
Milford, and Hebron.

This includes the following highways...
 U.S. Highway 151 between mile markers 121 and 126.
 Interstate 94 between mile markers 255 and 278.
 Wisconsin Highway 26 between mile markers 14 and 53.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

A Severe Thunderstorm Watch remains in effect until 200 PM CDT for
southeastern Wisconsin.

&&

LAT...LON 4285 8901 4343 8900 4337 8841 4320 8844
      4320 8854 4284 8854
TIME...MOT...LOC 1503Z 275DEG 27KT 4341 8902 4282 8939

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

MRC

Preliminary Local Storm Report
National Weather Service Milwaukee/Sullivan WI
1012 AM CDT Sun Aug 9 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0919 AM     Tstm Wnd Gst     1 NW Lake Delton        43.60N 89.79W
08/09/2026  M63 MPH          Sauk               WI   Public

            63mph wind gust recorded via home weather
            station.

&&

Halbach

Preliminary Local Storm Report
National Weather Service Milwaukee/Sullivan WI
1013 AM CDT Sun Aug 9 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0948 AM     Hail             2 S Windsor             43.19N 89.33W
08/09/2026  M0.75 Inch       Dane               WI   Public

            Report from mPING: Dime (0.75 in.).

&&

Halbach