Flash Flooding in Wisconsin, September 25 to 26, 2005

Name: Flash Flooding in Wisconsin, September 25 to 26, 2005
Start: 2005-09-25T20:00
End: 2005-09-26T01:00
Location: Wisconsin

September 25 to 26, 2005 · NWS MKX · 2 events in 2 counties and zones

5 inches werer reported across parts of Waukesha and Milwaukee counties during the late afternoon and into late evening as thunderstorms tracked northeast over the same areas. Flash flooding was reported across portions of Milwaukee and Waukesha counties as storm drains became overwhelmed with water flow.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: $100,000
Crop damage: None recorded
Events: 2

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS MKX wrote it up.

Heavy rains of 2.0 to to 4.5 inches werer reported across parts of Waukesha and Milwaukee counties during the late afternoon and into late evening as thunderstorms tracked northeast over the same areas. Flash flooding was reported across portions of Milwaukee and Waukesha counties as storm drains became overwhelmed with water flow. Interstate-43 was closed for a couple hours after a few cars were stranded in flash flood waters near North Avenue. Several basements were also flooded about the area, resulting in damage to contents.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Milwaukee, WI wrote its last area forecast discussion before the first event at Sep 25, 2:15 PM CST, 5 hours 45 minutes earlier.

Area forecast discussion, Sep 25, 2:15 PM CST, 5 hours 45 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
315 PM CDT SUN SEP 25 2005

.DISCUSSION...FORECAST EMPHASIS ON PRECIPITATION TNGT AND WHETHER TO
CARRY INTO MON...AND SHARPENING SHORT WAVE ON WED.

INCREASING CONVERGENCE ALONG BOUNDARY LEFT OVER FROM EARLIER
CONVECTION HELPING TO TRIGGER MORE SCATTERED TO NUMEROUS CONVECTION
ACROSS SRN PTNS OF COUNTY WARNING AREA.  RAINFALL ESTIMATES FROM
TODAY MOSTLY IN THE QUARTER INCH TO ONE INCH RANGE...BUT PORTIONS OF
NORTH AND WEST RECEIVED NARROW STRIP OF ONE TO TWO INCH RAINFALL.
PRECIPITABLE WATER REMAINS AROUND 200 PERCENT OF NORMAL THIS EVENING
AS ENHANCED SYNOPTIC SCALE FORCING FROM LEFT EXIT REGION OF
INCREASING UPPER LEVEL JET MOVES THRU.  LOW LEVEL JET NOT AS STRONG
AS LAST NIGHT BUT STILL EXPCG 20 TO 30 KNOTS INTO THE EVE.  HENCE WL
MENTION POTENTIAL FOR HEAVY PRECIP IN HEADLINE ONCE AGAIN THIS
EVENING...WITH ONE TO TWO INCH RAIN AMOUNTS POSSIBLE IN SEVERAL
HOURS TIME.  PRECIP EXTENDS WELL WEST INTO NWRN IA ASSOCD WITH
DEFORMATION ZONE WITH UPR WAVE.  WL CARRY SML POP INTO MON MRNG IN
ERN AREAS BUT EXPC BULK OF PRECIP TO BE OVERWITH AS 305 THETA
SURFACE SHOWING DOWNGLIDE AND SUBSIDENCE.  CLOUDS MAY TAKE SOME TIME
TO CLEAR ON MON AS WEAK THERMAL TROF BUILDS IN AND LOW LEVEL
CYCLONIC FLOW HANGS ON.  DIMINISHING WINDS AND CLOUDS SHOULD ALLOW
AREAS OF FOG TO DVLP LTR MON NGT WITH ABUNDANT LOW LEVEL MOISTURE IN
PLACE.

FAIRLY CONSISTENT RUN TO RUN CONTINUITY OF GFS REGARDING AMPLIFYING
SHORT WAVE ON WED.  PRECIP ASSOCD WITH COMPACT SHORT WAVE
POSTFRONTAL WITH MINIMAL RH AVBL UNTIL WED.  ELEVATED INSTABILITY
MARGINAL ON WED...YET 500MB TEMPS DECREASE TO -14 TO -18 SO WL
INCLUDE ISO MENTION OF T AT THIS POINT.  IMPRESSIVE 400MB POTENTIAL
VORTICITY ADVECTION WED AFTN/EVE BUT WOULD LIKE TO SEE LWR LAPSE
RATES TO REALIZE FULL POTENTIAL.  IN ADDITION TO ABOVE...600MB FULL
WIND FRONTOGENESIS AVLB SO WL BUMP UP WORDING TO SCT CAT FOR WED.

EMPHASIS ON LATER PERIODS ON AMPLIFYING SHORT WAVE TROF AND COLD
FRONT EXITING AREA WED NGT.  LOW LEVEL COLD AIR ADVECTION AND
RELATIVE HUMIDITY SHOULD PRODUCE SC FIELD WHICH MAY PERSIST INTO THU
ALONG WITH THERMAL TROF BEFORE CLEARING THU AFTN AND EVE.  85H TEMPS
AROUND -2C WITH DIMINISHING WINDS THU NGT SHOULD ALLOW TEMPS TO FALL
INTO THE UPR 30S TO LWR 40S...ESPECIALLY CENTRAL AND WESTERN
SECTIONS OF CWA.  WL MENTION FROST IN LOW AREAS FOR NOW AND SEE HOW
THIS PLAYS OUT NEXT SEVERAL DAYS.  GFS ENSEMBLE MEMBERS IN
REASONABLE AGREEMENT AT START OF EXTENDED PERIOD LENDING MORE
CREDENCE TO HANDLING OF WED SHORT WAVE. MUCH MORE UNCERTAINTY
SETTLES IN FOR NEXT WEAK SHORT WAVE EXPECTED OVER THE WEEKEND.
DPROG OF GFSLR SHOWING MOISTURE LIMITED WITH WEEKEND SYSTEM AND
ECMWF SLOWING SYSTEM DOWN BUT LATEST DGEX CONTG TO SHOW SML POPS.
PER COORD WITH ARX...WL LEAVE IN SML POPS FOR NOW SAT NGT.

MEAN 500MB HEIGHT ANOMOLY SHOWING WEST TO NORTHWEST FLOW WITH NEAR
NORMAL HEIGHTS TO FINISH OFF THE MONTH.  UPSTREAM SHORT WAVE TROF
AMPLIFIES OVER NRN PAC FIRST FEW DAYS OF OCT PRODUCING SLIGHTLY ABV
NORMAL HEIGHTS AND MORE ZONAL FLOW OVER UPR MIDWEST...WHICH CARRIES
THRU MIDDLE OF NEXT WEEK...RESULTING IN SERIES OF WEAK SHORT WAVES
TROFS AND ABV NORMAL TEMPS CONT.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

MBK

Hazardous weather outlook, Sep 25, 7:00 PM CST, 1 hour before

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
800 PM CDT SUN SEP 25 2005

WIZ046-047-051-052-056>060-062>072-261000-
MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE-
WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE-
LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA-
800 PM CDT SUN SEP 26 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL AND
SOUTHEAST WISCONSIN.

.DAY ONE...TONIGHT

OCCASIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED TONIGHT...SOME
PRODUCING HEAVY RAINFALL. THE RAIN WILL CAUSE URBAN AND SMALL
STREAM FLOODING IN SOME LOCATIONS...MAINLY IN THE SOUTHEAST PART OF
THE STATE.

AREAS OF DENSE FOG ARE ALSO POSSIBLE...REDUCING VISIBILITIES TO LESS
THAN A QUARTER MILE IN SPOTS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THERE IS A CHANCE OF THUNDERSTORMS AGAIN WEDNESDAY. AT THIS TIME
THESE THUNDERSTORMS ARE EXPECTED TO REMAIN BELOW SEVERE LIMITS.

THERE WILL BE A CHANCE FOR FROST IN LOW LYING AREAS ESPECIALLY OVER
SOUTH CENTRAL SECTIONS THURSDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED...HOWEVER RAINFALL REPORTS
WILL BE APPRECIATED.

LMZ643>646-665-261000-
SHEBOYGAN TO WINTHROP HARBOR ILLINOIS-
WISCONSIN ADJACENT OPEN WATERS OF LAKE MICHIGAN TO MID LAKE-
800 PM CDT SUN SEP 25 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN.

.DAY ONE...TONIGHT

OCCASIONAL SHOWERS AND THUNDERSTORMS WILL CONTINUE TONIGHT. THE
THUNDERSTORMS SHOULD REMAIN BELOW SEVERE LIMITS. AREAS OF DENSE FOG
WILL ALSO CONTINUE.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

SMALL CRAFT ADVISORIES MAY BE NEEDED MONDAY...AND AGAIN WEDNESDAY
AND THURSDAY.

THERE IS A CHANCE OF THUNDERSTORMS WEDNESDAY. AT THIS TIME THESE
THUNDERSTORMS ARE EXPECTED TO REMAIN BELOW SEVERE LIMITS.

NJ

The radar

The Milwaukee radar (KMKX), 48 km away, was scanning. The volume nearest the first event began at 02:02 UTC.

Open the radar archive at this moment

Event by event

2 flash flood. Local standard time, as filed.

Flash Flood, Milwaukee

When: September 25, 8:00 PM CST to September 26, 1:00 AM CST
Where: Milwaukee County, Milwaukee
Property damage: $50,000
Reported by: NWS EMPLOYEE(OFF DUTY)
Coordinates: 43.033, -87.967

Widespread flooding across most of Milwaukee County. Several feet of water was reported on Interstate 43 at North Avenue, causing it to close for several hours. Three cars were stranded as water rose very rapidly. One to three feet of water was also reported on roadways at the UW-Milwaukee campus. On the UW-Milwaukee campus, over 4 inches of rain fell during the evening. Some basements were flooded in low lying areas, resulting in damage to contents.

Flash Flood, Waukesha

When: September 25, 8:00 PM CST to September 26, 1:00 AM CST
Where: Waukesha County, Mukwonago
Property damage: $50,000
Reported by: LAW ENFORCEMENT
Coordinates: 42.867, -88.333

Flooded roads and some flooded basements were reported across portions of central and southern Waukesha county, damaging contents inside.

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Wisconsin in 2005 Every state in 2005 This day in weather history Warnings in Wisconsin, September 2005

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5474718, 5474719.