Deep layer shear with a short wave trough interacted with instability ahead of a surface trough trailing from a surface low in central Wisconsin. The instability and shear produced supercell thunderstorms in southern Wisconsin along and ahead of the surface trough. The severe thunderstorms produced damaging winds, large hail and tornadoes. Heavy rains accompanying the severe thunderstorms produced flash flooding in Lafayette County.

Funnel Cloud in IOWA, WISCONSIN
From 27-JUL-09 17:25:00 to 27-JUL-09 17:25:00 (CST-6)
Location: AVOCA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Flash Flood in IOWA, WISCONSIN
From 27-JUL-09 18:30:00 to 27-JUL-09 21:00:00 (CST-6)
Location: AVOCA
Flood cause: Heavy Rain
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Heavy rains from severe thunderstorms produced flash flooding that washed out the shoulders of several roads and driveways, causing $75,000 of damage. The AWOS unit at the Mineral Point Airport recorded 1.21 inches of rain between 1830 and 1900 CST.

Hail in COLUMBIA, WISCONSIN
From 27-JUL-09 17:44:00 to 27-JUL-09 17:44:00 (CST-6)
Location: CAMBRIA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained weather spotter reported hail estimated at 0.88 inch in diameter in the Village of Cambria.

Tornado in LAFAYETTE, WISCONSIN
From 27-JUL-09 19:10:00 to 27-JUL-09 19:11:00 (CST-6)
Location: GRATIOT
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A NWS storm survey team found evidence of a brief tornado about 2 miles northeast of the Village of Gratiot on a farm just southwest of the intersection of STH 78 and West Chruch Rd.  It moved east-southeast on a 95 degree bearing and dissipated on STH 78.  Damage was limited mainly to trees (uprooted or branches snapped).  The beginning/ending GPS coordinates were 41.60841/-89.99102 and 42.60773/-89.98941 with a damage indicator of DI 27 (TH), DOD 3.  The winds were estimated at about 80 mph, and the average path width about 15 yards.

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 27-JUL-09 18:40:00 to 27-JUL-09 18:50:00 (CST-6)
Location: DARLINGTON
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 15.00K
Reported by: Emergency Manager

Emergency management officials reported tree and crop damage due to severe thunderstorm wind gusts in a 100-yard wide swath.

Thunderstorm Wind in IOWA, WISCONSIN
From 27-JUL-09 18:05:00 to 27-JUL-09 18:05:00 (CST-6)
Location: LINDEN
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emeregency management officials reported large trees uprooted by severe thunderstorm wind gusts in the VIllage of Linden.

Flash Flood in LAFAYETTE, WISCONSIN
From 27-JUL-09 19:00:00 to 27-JUL-09 22:00:00 (CST-6)
Location: BELMONT
Flood cause: Heavy Rain
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Heavy rains from severe thunderstorms produced flash flooding that washed out the gravel shoulders of roads in and near Belmont in Lafayette County.  Damage due to the flash flooding totaled $30,000. Rainfall estimates from National Weather Service radar totaled 2 to 3 inches during this time.

Tornado in MARQUETTE, WISCONSIN
From 27-JUL-09 16:48:00 to 27-JUL-09 17:12:00 (CST-6)
Location: GLENOAK
Tornado F-scale: EF1
Property damage: 10.00K
Crop damage: 10.00K
Reported by: NWS Storm Survey

A tornado spun up about 2 miles west-northwest of Glen Oak (about 3 miles southwest of Montello), roughly mid-way between Williams Lake and Metcalf Lake. It proceded to move southeast on a 150 degree bearing to where Grand Ave. crosses into Green Lake County.  This weak tornado eventually dissipated about 2 miles northwest of Dalton in southwest Green Lake County.  Mainly tree damage was noted along the track in Marquette County.  However, one small pole shed lost some roof shingles, and minor roof damage was infliced upon two mobile trailer homes along Grand Ave.  Minor damage to corn crops was noted as well.   The starting ending GPS coordinates in Marquette County were 43.76112/-89.36820 and 43.71007, with a damage indicator of DI 27 (TH), DOD 3.  The wind speed was estimated at 95 mph.  The average path width was about 75 yards.

Tornado in GREEN LAKE, WISCONSIN
From 27-JUL-09 17:12:00 to 27-JUL-09 17:16:00 (CST-6)
Location: DALTON
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 2.00K
Reported by: NWS Storm Survey

This tornado segment was a continuation of a EF1 tornado what spun up about 3 miles soutwhest of Montello in Marquette County.  It moved southeast and crossed into Green Lake County where Grand Ave. enters the county. It dissipated about 2 miles north-northwest of the Village of Dalton.  Damage was limited mainly to trees (uprooted or branches snapped), but there was some minor damage to a corn field.

Hail in GREEN LAKE, WISCONSIN
From 27-JUL-09 17:10:00 to 27-JUL-09 17:10:00 (CST-6)
Location: DALTON
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: Emergency Manager

An emergency management official reported hail up to 1.50 inches in diameter covered the ground on Grand Ave. on a farm about about 3 miles northwest of the Village of Dalton.  Hail stones still measured 1 inch in diameter 18 hours later at this location which was shaded by trees and a corn crop.  Newspaper reports indicated that some corn fields were shredded by the hail, therefore an estimated loss estimate of $5000 was entered with this event.

Hail in COLUMBIA, WISCONSIN
From 27-JUL-09 17:55:00 to 27-JUL-09 17:55:00 (CST-6)
Location: CAMBRIA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Police officials estimated hail up to 1 inch in diameter fell in a 1/2 mile wide swath from one mile north of Cambria near State Highway 33 to the Village of Cambria.

Thunderstorm Wind in GREEN LAKE, WISCONSIN
From 27-JUL-09 17:22:00 to 27-JUL-09 17:22:00 (CST-6)
Location: DALTON
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Police officials reported tree damage in the Village of Dalton due to damaging thunderstorm wind gusts.

Thunderstorm Wind in IOWA, WISCONSIN
From 27-JUL-09 17:45:00 to 27-JUL-09 17:45:00 (CST-6)
Location: AVOCA
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A NWS storm survey team found a few uprooted trees and other minor tree damage produced by damaging thunderstorm wind gusts.

Thunderstorm Wind in MARQUETTE, WISCONSIN
From 27-JUL-09 16:06:00 to 27-JUL-09 16:40:00 (CST-6)
Location: WESTFIELD
Magnitude: 56.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Severe thunderstorms produced damaging winds estimated up to 65 mph that caused extensive tree damage in a 4 mile wide swath from Westfield to Montello. Trees fell on two homes at Buffalo Lake causing roof damage.  Several power lines were damaged by tree debris and there were scattered power outages in the Montello area.  Most likley this wind damage was associated with the forward flank downdraft of the supercell thunderstorm that generated a F1 tornado in Marquette County a few minutes later.