A cold front crossed Wisconsin during the late afternoon and evening hours of July 24th. Large scale lift and deep layer wind shear associated with upper level low pressure moving into the region led to the development of supercell thunderstorms in southwest Wisconsin. Severe thunderstorm wind gusts, large hail, and two tornadoes were reported in Lafayette County with the supercell storms.

Tornado in LAFAYETTE, WISCONSIN
From 24-JUL-09 16:12:00 to 24-JUL-09 16:17:00 (CST-6)
Location: SEYMOUR CORNERS
Tornado F-scale: EF0
Property damage: 100.00K
Crop damage: 10.00K
Reported by: NWS Storm Survey

A weak tornado spun up a little north of the intersection of CTH Q and Prairie Rd. (about 4 miles northwest of Shullsburg).  It proceded to move on a 145 degreee bearing southeast to just southeast of the intersecton of CTH U and Jackson Rd. a couple miles north-northeast of Shullsburg.  Major damage was inflicted on a barn and storage pole shed, several trees were uprooted or snapped, and some minor damage was inflicted on a corn field.  The specific starting and ending GPS coordinates were 42.63011/-90.26829 and 42.59963/-90.21671, and the damage intensity was based on DI 1 (SBO), DOD 8.  The average width was about 30 yards.  The wind was estimated to be about 105 mph.

Hail in LAFAYETTE, WISCONSIN
From 24-JUL-09 17:18:00 to 24-JUL-09 17:35:00 (CST-6)
Location: BENTON
Magnitude: 2.75 
Property damage: 500.00K
Crop damage: 6.42M
Reported by: Law Enforcement

A 5-mile wide hail swath damaged crops (corn, soy beans, wheat, and alflafa),  vehicles (dents and broken windows), and at least 25 homes (roofs, windows, and siding).  This swath merged with another hail swath from an ealier storm that traveled from Northwest Lafayette County to southeast of Shullsburg.  Some farm fiels were stripped to nothing by the hail stones.
Newspaper accounts indicated that the two hail swaths resulted in damage to 20,000 acres of corn and 10,000 acres of soybeans in Lafayette County. Using an avarge of 135 bushes of corn per acre with a price of $3.45 per bushels yields a corn loss of $9.315 M.   Using an average of 38 bushels of soybeans per acre, and a price of $9.25 per bushel yields a soybean loss of $3.515 M.  These loss estimates were divided by two and assigned to the two hail swaths equally.

Tornado in LAFAYETTE, WISCONSIN
From 24-JUL-09 17:32:00 to 24-JUL-09 17:40:00 (CST-6)
Location: NEW DIGGING
Tornado F-scale: EF0
Property damage: 50.00K
Crop damage: 10.00K
Reported by: NWS Storm Survey

A weak tornado spun up about 1/3 mile south-southwest of the intsection of STH 11 and CTH I, or roughly a couple northeast of New Diggings.  It proceded to move on a 122 degreee bearing southeast to about 1/3 mile east of the intersecton of CTH O and Blackhawk Rd., about 3.5 miles southeast of Shullsburg.  A small pole shed was destroyed and small portions of a side-wall and roof of a home were peeled off.  Otherwise several trees were uprooted or snapped.  The specific starting and ending GPS coordinates were 42.55270/-90.31193 and 42.52115/-90.24236, and the damage intensity was based on DI 1 (SBO), DOD 6.  The average width was about 25 yards.  The wind was estimated to be about 90 mph.

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 24-JUL-09 16:05:00 to 24-JUL-09 16:10:00 (CST-6)
Location: BELMONT
Magnitude: 78.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Powerful thunderstorm winds toppled dozens of trees and damaged a shed.

Thunderstorm Wind in LAFAYETTE, WISCONSIN
From 24-JUL-09 17:18:00 to 24-JUL-09 17:35:00 (CST-6)
Location: BENTON
Magnitude: 78.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Powerful thunderstorm winds toppled dozens of trees.

Flash Flood in LAFAYETTE, WISCONSIN
From 24-JUL-09 18:00:00 to 24-JUL-09 20:30:00 (CST-6)
Location: NEW DIGGING
Flood cause: Heavy Rain
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Repeated heavy rains from a couple thunderstorms resulted in flash flooding in the area from New Diggings to southeast of Shullsburg.  All rivers and streams in this area rose above flood stage, and many roads had water over them.  Some roads had  depths of 2 to 3 feet of fast-flowing water.  Several of the gravel shoulders were washed out, and lots of vegetative debris was left on some roads.

High Wind in ROCK, WISCONSIN
From 24-JUL-09 18:45:00 to 24-JUL-09 19:15:00 (CST-6)
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Many large trees in or near the city of Beloit were uprooted or damaged by powerful, non-thunderstorm, gradient high winds due to a wake-low situation.  A thunderstorm complex had previously moved west to east across northern Illinois, while an area of low pressure developed over the Wiscosnin River Valley northwest of Madsion.  The resultant increase in the surface pressure gradient across southern Wisconsin resulted in the development of high winds.

Hail in LAFAYETTE, WISCONSIN
From 24-JUL-09 16:05:00 to 24-JUL-09 16:05:00 (CST-6)
Location: BELMONT
Magnitude: 2.75 
Property damage: 500.00K
Crop damage: 6.42M
Reported by: Law Enforcement

A 5-mile wide hail swath damaged crops (corn, soy beans, wheat, and alfalfa), vehicles (windows and dents), and at least 25 homes (windows, siding, and roofs).   This hail swath merged with a another, later, hail swath, with the merger southeast of Shullsburg.  Some fields southeast of Shullsburg were totally stripped by the hail stones.
Newspaper accounts indicated that the two hail swaths resulted in damage to 20,000 acres of corn and 10,000 acres of soybeans in Lafayette County. Using an avarge of 135 bushes of corn per acre with a price of $3.45 per bushels yields a corn loss of $9.315 M.   Using an average of 38 bushels of soybeans per acre, and a price of $9.25 per bushel yields a soybean loss of $3.515 M.  These loss estimates were divided by two and assigned to the two hail swaths equally.