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Overview

A small, but intense Supercell formed along a warm front that was stretched across southern Minnesota and northern Iowa on Friday afternoon, June 11, 2004. It initially developed near Charles City, IA and then tracked northeast into Howard County, Iowa. From that point on it began to produce a series of tornadoes as it moved north toward the state line.

No other damage could be found as the storm tracked north until it approached the Riceville, IA area where it dropped another brief touchdown. A few sheds and buildings on the east side of Riceville were damaged, with mainly tin blown off roofs and siding torn off. This damage was rated F0 and the approximate time was 5:35 p.m.

A much more significant tornado formed around 5:50 p.m. about 4 miles north of Riceville or 4 miles southwest of Le Roy, Minnesota, just east of the Mitchell-Howard County line. The tornado formed in open fields near County Road A23 just east of Addison Avenue, which is the Mitchell-Howard County line. It hit several homes and farms (F2 damage) as it tracked straight north toward the Minnesota-Iowa state line, only feet from the county line.

One home lost the roof and all outbuildings, while another home right on the state line was completely destroyed. The tornado was approx. 150 yards wide at times and apparently reached low end F3 damage intensity right on the state line around 6:00 p.m. The tornado then started to weaken but did heavy damage to a grain company (Koch Industries)(F2 damage) about 2 miles west of Le Roy and continued north crossing Highway 56 just before 6:15 p.m.. The tornado lifted approximately 4 miles northwest of Le Roy in open fields.

There were also brief tornado touch downs (all rated F0) near Dexter and Le Roy, Minnesota, as well as areas along the Mower-Fillmore County line west of Spring Valley.

Tornado map from June 11, 2004


Tornado in extreme northwest Howard County, IA. (Photo by James and Holly Bass)	Tornado southwest of Le Roy, MN. (Photo by Kurt Grover)	Another shot of tornado. (Photo by Jordan Gilgenbach and Lindsay Viker)

Tornado
Timetable
Photos
Radar

Tornadoes:

Tornado - New Haven, IA
Mitchell County

Date	June 11, 2004
Time (Local)	5:17-5:33 p.m.
EF Rating	F1
Est. Peak Winds
Path Length	4 miles
Max Width	60 yards
Injuries/Deaths	0 / 0
Summary: A small but intense supercell thunderstorm produced three tornadoes in northeast Iowa. The first tornado touched down about 4 miles southeast of New Haven (Mitchell County), south of 320th Street and between Walnut and Windfall Avenue. It tracked north, primarily in open fields, and lifted between 350th and 360th Street east of New Haven, or just west of Windfall Avenue.

Track Map

Tornado - Riceville, IA
Howard County

Date	June 11, 2004
Time (Local)	5:40-5:50 p.m.
F Rating	F0
Est. Peak Winds
Path Length	4 miles
Max Width	40 yards
Injuries/Deaths	0 / 0
Summary: The second tornado touched down just east of the Mitchell-Howard County line, about 4 miles south of Riceville, and also moved straight north. It downed a few trees, but primarily crossed open fields until it reached the southeast side of Riceville. It damaged a few sheds and buildings in Riceville, with mainly tin roofing material and siding blown off before lifting while in town.

Track Map

Tornado - LeRoy, MN
Howard & Mower Counties

Date	June 11, 2004
Time (Local)	5:56-6:13 p.m.
F Rating	F3
Est. Peak Winds
Path Length	12 miles
Max Width	150 yards
Injuries/Deaths	0 / 0
Summary: The third and most significant tornado formed about 2 miles north of Riceville, again just east of the Mitchell-Howard County line. The tornado tracked north, just east of the county line or Addison Avenue. It grew in strength and at one point was approximately 150 yards wide, hitting several homes and farms (F2 damage). One home lost the roof and all buildings. The tornado was so close to the county line that debris was thrown across Addison Avenue into Mitchell County at times. The dirt and young crops were scoured by the tornado. The tornado crossed into Minnesota just southwest of Le Roy (Mower County), hitting a home directly on the state line. The home, which was built in1900, and several buildings on the lot, were completely demolished (F3 damage).

Track Map

Tornado - LeRoy, MN
Fillmore County

Date	June 11, 2004
Time (Local)	6:30-6:32 p.m.
F Rating	F0
Est. Peak Winds
Path Length	0.2 miles
Max Width	20 yards
Injuries/Deaths	0 / 0
Summary: A brief tornado touched down near LeRoy from a squall line that moved through from the west.

Track Map

Tornado - 2 miles NE of Dexter, MN
Mower County

Date	June 11, 2004
Time (Local)	6:53-6:55 p.m.
F Rating	F0
Est. Peak Winds
Path Length	0.2 miles
Max Width	20 yards
Injuries/Deaths	0 / 0
Summary: A brief tornado touchdown was reported as a squall line moved through.

Track Map

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Timetable:

12:15 p.m. - Hazardous Weather Outlook stating "BUT A FEW STORMS ALONG THE WARM FRONT MAY BECOME TORNADIC. THIS WILL HAVE TO BE MONITORED CLOSELY."
1:45 p.m. - Tornado Watch issued for northeast Iowa and southeast Minnesota.
3:49 p.m. - Hazardous Weather Outlook stating "...INCLUDING AREAS ALONG AND WEST OF HIGHWAY 63 IN SOUTHEAST MINNESOTA AND NORTHEAST IOWA WOULD BE THE MOST FAVORABLE LOCATION FOR ANY SUPERCELLS AND POSSIBLE TORNADO DEVELOPMENT INTO THE EVENING HOURS.
5:20-5:40 p.m. (estimated) - Brief tornado touchdowns west of Elma and near Riceville.
5:32 p.m. - Tornado Warning for Howard County, until 6:15 p.m.
5:50 p.m. - Tornado starts 4 miles south west of Le Roy, MN.
5:53 p.m. - Tornado Warning for western Fillmore and Mower County, Minnesota.
6:15-6:20 p.m. - Tornado lifts 4 miles northwest of Le Roy, MN.

Photos:


Damage in Riceville, IA.	Home damage about 4 miles southwest of Le Roy, MN in extreme northwest Howard County.	Garage damage. Cars were also thrown.	Home demolished near the Minnesota-Iowa state line.


Heavy damage to same home near the state line. They hid in the basement and survived.	Sheds damaged west of Le Roy.	More damage west of Le Roy to sheds.	Track of the tornado in Howard County, looking south. The ground was scoured.


Projectiles thrown into Mitchell County Iowa.

Radar:

Header


0.5 degree base reflectivity at 523 p.m. CDT around the first brief tornado touchdown.	0.5 degree storm-relative velocity at 523 p.m. CDT around the first brief tornado touchdown.	0.5 degree Base reflectivity at 553 p.m. CDT near Riceville and LeRoy.	0.5 degree storm-relative velocity at 553 p.m. CDT near Riceville and LeRoy.