Flash Flood Warning 22, NWS Milwaukee, WI

737 
WGUS73 KMKX 190817
FFSMKX

Flash Flood Statement
National Weather Service Milwaukee/Sullivan WI
317 AM CDT Sat Sep 19 2026

WIC025-190827-
/O.CAN.KMKX.FF.W.0022.000000T0000Z-260919T0900Z/
/00000.U.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Dane WI-
317 AM CDT Sat Sep 19 2026

...FLASH FLOOD WARNING IS CANCELLED FOR DANE COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a
threat.

A Flood Watch remains in effect until 700 PM CDT Saturday for Dane
County.

&&

LAT...LON 4317 8984 4317 8901 4285 8901 4285 8937
      4286 8937 4286 8984

$$

QUIGLEY

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1050 PM CDT Fri Sep 18 2026

.KEY MESSAGES...

- Heavy rainfall moving into southern Wisconsin tonight into Saturday
  morning (peak coverage between 1 AM & 10 AM). Urban/small
  stream flooding, ponding of water, and minor rises on area
  rivers are expected areawide. Areas of flash flooding are
  possible mainly west of a Kenosha-Watertown-Wisconsin Dells
  line. Widespread 1 to 3 inch rain totals remain expected, with
  higher totals between 3-6"+ possible in areas that storms
  track repeatedly.

- Additional storm development possible Saturday afternoon, particularly
  along & south of I-94. Additional heavy downpours & flooding
  impacts would be the main impact with an isolated severe storm
  possible near the Wisconsin-Illinois border.

- Prolonged period of high swimming risk conditions continues
  into Tuesday at all Lake Michigan beaches.

- Off and on chances for lighter rain Sunday into Monday.
  Trending drier Tuesday onward.

&&

.SHORT TERM...
Issued 1055 PM CDT Fri Sep 18 2026

Current Overnight through Sunday:

Synopsis/Mesoanalysis: Weak area of surface low pressure continues
to move into west-central Iowa late this evening. Rooted in the 850
mb layer, warm advection is blossoming along the northeast periphery
of the surface low, combining with an east-west band of
frontogenesis & bisecting low level jet to spark widespread
showers and storms from near the Dells westward. This activity
will slide east-southeast into the region after midnight,
persisting into the first half of Saturday morning. The
showers/storms will bring moderate to torrential downpours,
with flash flooding possible in locations where the heaviest
rates track repeatedly. Activity is expected to slide southeast
of the area by mid-day Saturday, with the forecast picture
becoming more uncertain thereafter. The low currently over Iowa
will approach or pull just south of the Wisconsin-Illinois
border through the afternoon & early evening, with continued
warm advection along its northern periphery posing at least
conditional potential for additional showers and storms near and
south of I-94. Storm development and coverage will be dependent
on thermodynamic recovery in the wake of morning precip, in
addition to any embedded disturbances in the flow aloft. In the
event development occurs, additional heavy downpours and
flooding impacts would be possible. Given the conditional
potential for additional afternoon storm development, the Flood
Watch has now been extended until 7 PM Saturday evening over the
southern half of the area. Further north, the Flood Watch
remains in effect until 1 PM Saturday. Stay vigilant for
possible Flood and Flash Flood Warnings through Saturday
afternoon, and never drive through flooded roadways.

Rest of Overnight into Saturday morning: Expecting widespread
showers and storms across southern Wisconsin. Storms will bring
varying rainfall rates of moderate to torrential intensity, with
widespread precip coverage & long precip duration posing the
potential for at least minor hydrologic impacts (urban/small stream
flooding, ponding of water on roads, and minor rises on rivers)
areawide. Flash flooding will be possible in locations where the
heavier rates track repeatedly. Environmentally, the most favorable
corridor for flash flooding impacts will align near & west of a
Kenosha-Watertown-Wisconsin Dells line through early Saturday
morning. It will be in this part of the area that 1) sufficient
MUCAPE & embedded convection will allow for the materialization of
heavy to torrential rainfall rates and 2) elongated southeast-
northwest frontogenesis bands and their intersection with the low
level jet will provide focus points for training to occur.
Collectively, the going forecast of widespread 1-3" rainfall
accumulations with locally higher totals in the 3-6"+ range remains
on track, with the corridors of higher totals most likely along/west
of the Kenosha-Watertown-Wisconsin Dells line. Flood Watch thus
remains in effect into Saturday morning.

Saturday afternoon & evening: A more conditional window of
additional storm development will be in place predominantly along
and south of I-94 as low pressure moves near or just south of the
Wisconsin-Illinois border. Sufficient recovery post-AM precip will
be essential for this development to occur, with an additional
trigger from any passing disturbances aloft likely being needed as
well. Water vapor imagery shows one such disturbance nearing the
Nebraska Sandhills at the current hour, with crude extrapolations
bringing it across southern Wisconsin from ~11 AM - 7 PM Saturday if
it manages to hold together. Suspect that it's this feature that
more active 00Z CAM solutions are latching onto given its estimated
arrival time & the timing of their simulated storm re-development.
Will thus be monitoring trends very closely through tomorrow
morning, as little additional rainfall would be required to create
additional flooding problems. Have thus extended the Flood Watch
through 7 PM Saturday across the southern half of the area. Severe
weather potential would be low in any re-development, though an
isolated storm with gusty winds wouldn't be entirely out of the
realm of possibility near the Wisconsin-Illinois border.

Quigley

&&

.LONG TERM...
Issued 1055 PM CDT Fri Sep 18 2026

Sunday night through Friday:

Strong high pressure centered just north of the Great Lakes will
very gradually shift eastward Sunday night through Wednesday. A
cooler and much drier airmass is expected across southern Wisconsin
through this period under the influence of the high and an upper
level troughing pattern. Below normal high and low temps are
anticipated through mid-week.

Latest forecast models suggest the upper level trough and surface
high will maintain enough of an influence across southern Wisconsin
for continued mainly dry weather late week next week, with
temperatures gradually returning to near normal by the end of the
week as upper level ridging begins to build in from the west.

DDV

&&

.AVIATION...
Issued 1055 PM CDT Fri Sep 18 2026

Widespread showers with embedded thunder are then expected from late
evening/early tonight into Saturday morning. Heavy rainfall is
likely at times, with a Flood Watch in effect. There may be a lull
in widespread precip Sat afternoon, with more rounds of showers
and storms then possible by Sat evening.

Ceilings are expected to gradually lower west to east late evening
through the night, with widespread ceilings around 500ft or
lower by daybreak Saturday. IFR or lower ceilings are then
expected through the day Saturday. Visibilities will gradually
drop as well when the widespread precip moves in, with even
lower visibilities likely within heavier rain.

Breezy easterly winds tonight into early Saturday may ease a bit by
Sat afternoon as low pressure passes through, becoming breezy again
out of the northeast behind the low Saturday night.

DDV

&&

.MARINE...
Issued 1055 PM CDT Fri Sep 18 2026

1010 mb low pressure will continue to develop near the Missouri
River this evening, moving over or just south of waters during the
day on Saturday. Winds will veer east-southeasterly ahead of the
low, becoming gusty at points. A few gusts could approach gale
thresholds, particularly through the second half of tonight and
Saturday morning. Not expecting any borderline gales to be prolonged
or widespread enough to warrant Gale Warnings, but will continue to
monitor trends. Areas of widespread showers & storms will accompany
the approaching/passing area of low pressure tonight through at
least Saturday night, with widespread severe weather not expected at
this time.

Winds will trend northeasterly Sunday through Monday night as the
aforementioned area of low pressure slowly moves into the Ohio River
Valley. Additional rain showers will accompany the passing low, with
thunder and severe weather hazards appearing unlikely at this time.
1032 mb high pressure will concurrently slide into Ontario from the
Canadian Great Plains, with a compacted pressure gradient allowing
for gusty winds through most of the late weekend/early week time
frame. Similar to Saturday, gusts could occasionally approach gale
thresholds during the Sunday-Monday night time frame, with
conditions not expected to be widespread enough for Gale Warnings at
this time. Will continue to monitor trends for possible increases in
wind gusts. Winds will steadily taper Tuesday through Wednesday as a
new area of 1026 mb high pressure builds into northern Wisconsin.

Wind gusts and wave heights will continue to increase tonight, and
will remain near or above Small Craft Advisory thresholds into early
next week. Small Craft Advisory remains in effect beginning at 10 PM
tonight. Given the largely unchanging conditions & little if any
lulls in advisory-level conditions, have extended the existing Small
Craft Advisory through Tuesday afternoon in this forecast. The need
for further extensions will be evaluated through the beginning of
next week. Could see a few gusts near gale force on Sunday
afternoon, though conditions are expected to remain brief and
isolated enough to preclude the need for Gale Warnings. Will
continue to monitor for possible increasing trends through tomorrow.
Periods of showers and storms will continue through at least
Saturday evening, with severe weather appearing unlikely.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072
     until 7 PM Tuesday.

     Flood Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-WIZ058-
     WIZ059-WIZ060 until 1 PM Saturday.

     Flood Watch...WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-WIZ068-
     WIZ069-WIZ070-WIZ071-WIZ072 until 7 PM Saturday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 PM
     Tuesday.

&&

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Hazardous Weather Outlook
National Weather Service Milwaukee/Sullivan WI
1058 PM CDT Fri Sep 18 2026

WIZ046-047-051-052-056>060-062>072-200400-
Marquette-Green Lake-Fond du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
1058 PM CDT Fri Sep 18 2026

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

.DAY ONE...Tonight

Heavy rain moving in tonight. Widespread totals in the 1 to 3 inch
range with locally higher totals in the 3 to 6+ inch range
possible. Urban & small stream flooding, ponding of water, and
minor rises on rivers are all possible. Flash flooding is possible
in areas where storms track repeatedly. A Flood Watch remains in
effect.

.DAYS TWO THROUGH SEVEN...Saturday through Friday

Additional storm development is possible Saturday afternoon &
evening, with more heavy rainfall possible. Flood Watch remains in
effect until 1 PM CDT across the north and 7 PM CDT further south.

Prolonged period of high swimming risk conditions continues into
Tuesday at all Lake Michigan beaches.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed but rainfall reports are
appreciated.

LMZ643>646-200400-
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-
1058 PM CDT Fri Sep 18 2026

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

.DAY ONE...Tonight

Small craft conditions develop tonight.

Thunderstorms expected tonight.

.DAYS TWO THROUGH SEVEN...Saturday through Friday

Small craft conditions continue into Tuesday.

Additional storms possible Saturday afternoon and evening.

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-200400-
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-
1058 PM CDT Fri Sep 18 2026

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

.DAY ONE...Tonight

Chance of thunderstorms tonight.

.DAYS TWO THROUGH SEVEN...Saturday through Friday

Chance of thunderstorms Saturday into Saturday evening.

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