...Here is a summary of the severe weather outbreak on June 23, 2004...
A cool, moist airmass resided across southern Wisconsin through the early to middle afternoon
hours. Previous convection in the morning helped to hold off the northern progression of a surface
warm front, keeping the area fairly stable. As southerly winds increased, the surface warm front
pushed through the area bringing in slightly warmer air at the surface. This, in conjunction with
relatively cold air aloft, created moderately unstable conditions.
A broken line of intense thunderstorms developed across Walworth, Milwaukee, Racine, and Kenosha
counties around 4:00 pm CDT. These thunderstorms produced severe hail (image1 / image2) of up to one inch in diameter
and torrential rainfall before quickly moving over Lake Michigan and weakening.
A brief respite in the action followed these storms as instability continued to increase across
western and southern Wisconsin. Meanwhile, an area of strong to marginally severe thunderstorms
developed across eastern Minnesota in response to a rapidly moving cold front from northern Minnesota.
With higher instability levels along and east of the Mississippi river, this cluster of thunderstorms
began to build farther south to form a broken line as they headed into western Wisconsin. The individual
thunderstorms embedded along the line began to rotate as they encountered stronger shear due in part to
the light easterly winds north of the warm front and the stronger southerly winds south of the warm front.
The ingredients were in place for tornado development.
Before the line of thunderstorms reached southern Wisconsin, several reports of tornadoes and widespread
wind damage were noted across west central Wisconsin. These same thunderstorms continued to develop as
they rapidly headed east southeast around 55 miles per hour through the NWS Milwaukee/Sullivan county warning
area (CWA) later that evening.
Widespread straight-line wind damage and severe hail was the result from the fast moving line of
thunderstorms across most of the area. Several reports exceeded 60 miles per hour and a few even
exceeded 80 miles per hour. Trees with diameters up to two feet were toppled or uprooted.
...The following tornadoes occurred with a cluster of thunderstorms which moved across the northern
half of the Milwaukee/Sullivan CWA…
1.) Around 8:00 pm CDT, the first tornado report was received from 7 miles northeast of Oxford, or 3.5 miles
north northwest of Packwaukee in Marquette County. The tornado spun up just east of Highway 51 and
moved east southeast through the far southern portion of Montello and ended near the county line, about
one and a half miles south of County Trunk Highway C. Nine farm buildings were damaged or completely
destroyed. Based on damage surveys, this tornado was classified as an F2. Radar image at: 8:00 PM and 8:30 PM.
BEGINNING TIME 800 PM PATH LENGTH 11.0 MILES
ENDING TIME 815 PM MAX WIDTH 200 YARDS
DURATION 15 MIN DEATHS 0
BEGINNING LOCATION 3.5 NNW PACKWAUKEE INJURIES 0
ENDING LOCATION 4.0 SE MONTELLO F-SCALE F2, 140-150 MPH
2.) At 8:33 pm, another tornado spun up about 3 miles west northwest of Markesan, or 2N of Manchester,
in Green Lake County near the intersection of Highway 73 and County Road H. It headed southeast
through the southern portions of Markesan causing extensive tree and building damage. It then cut
across the southwest corner of Fond Du Lac County and into far northern Dodge County into the city
of Waupun. The tornado continued on its path into the southern areas of Knowles before dissipating
near Highway 41 at 9:05 pm. Damage surveys concluded this tornado was an F3. Radar image at: 8:30 PM and 9:00 PM.
BEGINNING TIME 833 PM PATH LENGTH 33.3 MILES
ENDING TIME 905 PM MAX WIDTH 400 YARDS
DURATION 32 MIN DEATHS 0
BEGINNING LOCATION 2 N MANCHESTER INJURIES 0
ENDING LOCATION 2 SE LOMIRA F-SCALE F3, 175-200 MPH
3.) A third tornado spun up at 8:35 pm 4.2 miles south southeast of Markesan in Green Lake County and moved
east toward the Green Lake and Fond du Lac county line by 8:42 pm. Large trees were uprooted and some
buildings were damaged. Before merging with the Markesan tornado in far western Fond du Lac County,
this tornado caused F2 damage. Radar image at: 8:30 PM and 9:00 PM.
BEGINNING TIME 835 PM PATH LENGTH 7.6 MILES
ENDING TIME 842 PM MAX WIDTH 300 YARDS
DURATION 7 MIN DEATHS 1
BEGINNING LOCATION 4.2 SSE MARKESAN INJURIES 1
ENDING LOCATION 2.5 SSW ALTO F-SCALE F3, 175-200 MPH
4.) Around 9:10 pm a weak tornado spun up southwest of Campbellsport in the Superior Drive area in southeast
Fond du Lac County. Tree damage was noted and damage surveys confirmed an F1 tornado. Radar image at: 9:00 PM and 9:30 PM.
BEGINNING TIME 910 PM PATH LENGTH 7.6 MILES
ENDING TIME 918 PM MAX WIDTH 150 YARDS
DURATION 8 MIN DEATHS 0
BEGINNING LOCATION 6SW CAMPBELLSPORT INJURIES 0
ENDING LOCATION 1.5 NW KEWASKUM F-SCALE F1, 80-90 MPH
5.) A very brief and weak tornado developed at 9:19 PM southeast of West Bend in Washington county.
Only minor damage was noted. Radar image at: 9:00 PM and 9:30 PM.
BEGINNING TIME 919 PM PATH LENGTH 0.1 MILE
ENDING TIME 919 PM MAX WIDTH 25 YARDS
DURATION BRIEF DEATHS 0
BEGINNING LOCATION 4.0 NNE JACKSON INJURIES 0
ENDING LOCATION 4.0 NNE JACKSON F-SCALE F0, 50-60 MPH
...The following tornadoes occurred with a second cluster mainly south of Interstate 94 which moved
through Dane, Walworth, and Jefferson counties...
6.) At 8:23 pm, a weak tornado briefly spun up two miles west-northwest of Marxville in northwest Dane county
and moved east-southeast 0.1 mile to end at 1.9 miles west-northwest of Marxville. Only minor tree damage was
reported and it was determined this tornado was an F0. Radar image at: 8:00 PM and 8:30 PM.
BEGINNING TIME 823 PM PATH LENGTH 0.1 MILE
ENDING TIME 824 PM MAX WIDTH 25 YARDS
DURATION 1 MIN DEATHS 0
BEGINNING LOCATION 2 WNW MARXVILLE INJURIES 0
ENDING LOCATION 1.9 WNW MARXVILLE F-SCALE F0, 60-70 MPH
7.) At 8:35 pm, a tornado spun up three miles southwest of Middleton in Dane county and moved east southeast
through the southern city limits of Madison just north of Highway 18/12 (the Beltline), and ended at
about 8:44 pm two and a half miles south of the Capital Square. Several buildings and signs were damaged
and numerous trees were either uprooted or damaged. Through damage surveys it was estimated that winds with
the tornado approached 100 miles per hour, or F1 intensity. Radar image at: 8:30 PM and 9:00 PM.
BEGINNING TIME 835 PM PATH LENGTH 7.8 MILES
ENDING TIME 844 PM MAX WIDTH 200 YARDS
DURATION 9 MIN DEATHS 0
BEGINNING LOCATION 2.5 SW MIDDLETON INJURIES 0
ENDING LOCATION 2.3 S MADISON F-SCALE F1, 100-110 MPH
8.) The same supercell storm associated with spawning the tornado in Dane County weakened a bit before
re-intensifying across southern Jefferson County. The second tornado spun up 6 miles southeast of Fort
Atkinson, or north-northeast of Whitewater, just north of Highway 59. It traveled east southeast through
mainly open farm land. Two sheds were damaged and numerous trees were toppled. The tornado ended around
9:30 pm and was later classified as an F1. Radar image at: 9:30 PM and 10:00 PM.
BEGINNING TIME 923 PM PATH LENGTH 7.8 MILES
ENDING TIME 934 PM MAX WIDTH 150 YARDS
DURATION 11 MIN DEATHS 0
BEGINNING LOCATION 1.8 SE COLD SPRINGS INJURIES 0
ENDING LOCATION 3.0 NNW LA GRANGE F-SCALE F1, 90-100 MPH