A strong storm system, in combination with deep moisture from the remnants of a tropical system, produced a large area of flooding rainfall with amounts as high as 8 and 11 inches in an 18 hour period.
The main area of precipitation occurred across far southern Minnesota, and portions of west central Wisconsin, between 7:00 p.m., Wednesday, September 22nd, to 9:00  a.m., Thursday, September 23rd.
Some of the smaller rivers in southeast Minnesota had historical crests which caused extensive damage around Northfield, Cannon Falls, Zumbrota and Pine Island. One bridge section on the North Fork River along Highway 52 between Cannon Falls, and Pine Island collapsed. The bridge in Cannon Falls was inundated by the flood waters of the Cannon River.
In addition to the smaller tributaries, the larger Minnesota and Mississippi Rivers had flooding from Redwood Falls, to the Twin Cities, then southeast to Red Wing, Minnesota for about two to three weeks, as the runoff was extensive.
Some of the most notable rainfall measurements are as follows:
It was a record 2-day rain event in Amboy, MN (10.68), Waseca, MN (7.65), and Springfield, MN (5.47).  Thursday was also the wettest day on record in Waseca, MN (5.16).

Heavy Rain in GOODHUE, MINNESOTA
From 22-SEP-10 23:00:00 to 23-SEP-10 03:30:00 (CST-6)
Location: GOODHUE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A cooperative observer measured 4.50 inches of rainfall in 4.5 hours.

Heavy Rain in WATONWAN, MINNESOTA
From 22-SEP-10 22:00:00 to 23-SEP-10 05:00:00 (CST-6)
Location: ST JAMES
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

The local law enforcement officials measured 6 inches of rainfall overnight.

Heavy Rain in BLUE EARTH, MINNESOTA
From 22-SEP-10 18:00:00 to 23-SEP-10 08:00:00 (CST-6)
Location: AMBOY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured 10.53 inches of rainfall between 6 pm  and 8 am.

Heavy Rain in BLUE EARTH, MINNESOTA
From 22-SEP-10 22:00:00 to 23-SEP-10 05:30:00 (CST-6)
Location: MAPLETON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured 6 inches of rainfall overnight.

Heavy Rain in RICE, MINNESOTA
From 22-SEP-10 19:00:00 to 23-SEP-10 06:00:00 (CST-6)
Location: NORTHFIELD
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A cooperative observer measured 5.20 inches of rainfall overnight.

Heavy Rain in GOODHUE, MINNESOTA
From 22-SEP-10 23:00:00 to 23-SEP-10 03:30:00 (CST-6)
Location: CANNON FALLS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A cooperative observer measured 4.85 inches of rainfall in 4.5 hours.

Heavy Rain in MARTIN, MINNESOTA
From 22-SEP-10 19:00:00 to 23-SEP-10 06:15:00 (CST-6)
Location: WELCOME
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured 4.90 inches of rainfall overnight.

Heavy Rain in FARIBAULT, MINNESOTA
From 22-SEP-10 23:30:00 to 23-SEP-10 04:15:00 (CST-6)
Location: BLUE EARTH
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A cooperative observer measured 4.92 inches of rainfall in less than 5 hours.

Heavy Rain in FREEBORN, MINNESOTA
From 22-SEP-10 19:00:00 to 23-SEP-10 07:00:00 (CST-6)
Location: ALDEN
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

The local media measured 7.0 inches of rainfall overnight.

Flash Flood in BROWN, MINNESOTA
From 22-SEP-10 19:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: SPRINGFIELD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Strong thunderstorms developed during the late afternoon, and early evening across the county, and dropped one to two inches of rainfall, along with some hail stones.  By 730 pm, another band of thunderstorms developed across the county and began to train over the same areas. By 9 pm, portions of southern Brown County already received two to four inches of rainfall.  Over the next several hours periods of heavy rainfall added up, and officials advised no travel on township roads. The City of Comfrey received 10,000 sandbags from the county during the height of the storm to keep water and sewage out of homes.

Flash Flood in REDWOOD, MINNESOTA
From 22-SEP-10 19:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: WALNUT GROVE ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Strong thunderstorms developed during the late afternoon, and early evening across the county, and dropped one to two inches of rainfall, along with some hail stones.  By 730 pm, another band of thunderstorms developed across the county and began to train over the same areas. County Road 10, south of Highway 14, was flooded due to the excessive rainfall and closed for a portion of the night.

Heavy Rain in WATONWAN, MINNESOTA
From 22-SEP-10 19:00:00 to 23-SEP-10 07:00:00 (CST-6)
Location: SOUTH BRANCH
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured 9.82 inches of rainfall overnight.

Flood in MARTIN, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 09:00:00 (CST-6)
Location: TRIMONT
Flood cause: Heavy Rain
Property damage: 915.00K
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.

Flood in FARIBAULT, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 09:00:00 (CST-6)
Location: MINNESOTA LAKE
Flood cause: Heavy Rain
Property damage: 402.00K
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.

Flash Flood in WATONWAN, MINNESOTA
From 22-SEP-10 20:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: ODIN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Strong thunderstorms developed during the late afternoon, and early evening across the county, and dropped around 1 to 2 inches of rainfall, along with some large hail stones.  By 730 pm, another band of thunderstorms developed across the county and began to train over the same areas. By 8 pm, portions of Watonwan County, northeast of Darfur, Minnesota had already received 2.35 inches of rainfall. By 11 pm, an observer measured 5.50 inches of rainfall near St. James. Over the next several hours periods of heavy rainfall added up, with several observers measuring between 8 and 10 inches across the southern part of the county, with localized 10 to 12 inches near Butterfield, Odin, and South Branch, Minnesota.  Numerous streets were underwater and closed for several hours. A few apartment complexes in St. James were evacuated due to the flooding.

Flood in FREEBORN, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 09:00:00 (CST-6)
Location: BATH
Flood cause: Heavy Rain
Property damage: 190.00K
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.

Flash Flood in MARTIN, MINNESOTA
From 23-SEP-10 00:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: ORMSBY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Bands of thunderstorms began to develop across the county by mid evening, with several thunderstorms training over the same areas. By midnight, nearly five inches of rain fell in the northeast corner around Truman.  The town of Fairmont started receiving reports of flooding in town.  Total rainfall amounts by morning ranged from over 6 inches in the northeast corner, to around 3 to 4 inches in the far south. By morning, the town of Truman had flooded roadways, and four to five feet of water in basements.

Flood in RICE, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: CANNON LAKE
Flood cause: Heavy Rain
Property damage: 1.80M
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.

Flood in DAKOTA, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: NORTHFIELD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed in extreme southern Dakota County, around the streams and creeks that flow into the Cannon River due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.

Flash Flood in FREEBORN, MINNESOTA
From 23-SEP-10 03:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: LONDON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Periods of heavy rainfall developed toward midnight, and continued through most of the early morning hours.  Rainfall rates increased to over 1.5 inches per hour, which caused flash flooding in portions of northern and central Freeborn County. Several county roads were inundated by water, and streams and creeks rose rapidly during the morning.

Flash Flood in STEELE, MINNESOTA
From 23-SEP-10 03:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: MERTON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Periods of heavy rainfall developed toward midnight, and continued through most of the early morning hours.  Rainfall rates increased to over 1.5 inches per hour which caused flash flooding.  By 5 am, several county roads were covered by water, including Highway 14 near Meridan and Highway 218 between Highway 14 and Blooming Prairie.  The county emergency manager reported street flooding in Owatonna, with intersections closed. Homes were also evacuated along Maple Creek, and sandbagging occurred along the Straight River south of town.

Flood in GOODHUE, MINNESOTA
From 23-SEP-10 10:00:00 to 26-SEP-10 12:00:00 (CST-6)
Location: PINE IS
Flood cause: Heavy Rain
Property damage: 540.00K
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed in Goodhue County, around the streams and creeks that flow into the Cannon and Zumbro Rivers due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until Sunday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.

Flood in WATONWAN, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: ODIN
Flood cause: Heavy Rain
Property damage: 3.90M
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.

Flash Flood in RICE, MINNESOTA
From 23-SEP-10 03:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: EPSOM
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Periods of heavy rainfall developed toward midnight, and continued through most of the early morning hours.  Rainfall rates increased to over 1.5 inches per hour which caused flash flooding. Several county roads were inundated by water, along with several streams and creeks that rose rapidly during the morning. By 5 am, Highway 60 west of Kenyon was closed due to flood waters.

Flash Flood in FARIBAULT, MINNESOTA
From 23-SEP-10 00:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: PILOT GROVE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Bands of thunderstorms began to develop across the county by the late evening, with several thunderstorms training over the same areas. After midnight, nearly five inches of rain fell in the northwest corner around Winnebago.  Minnesota Lake had over 8 inches by morning with local streams and creeks flowing out of their banks.

Flood in WASECA, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: WALDORF
Flood cause: Heavy Rain
Property damage: 1.00M
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.  In New Richland, Minnesota, Highway 30 and Highway 13 were closed, making it impossible for the roughly 1,000 residents to get out of town.

Flood in BLUE EARTH, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: AMBOY
Flood cause: Heavy Rain
Property damage: 2.10M
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.

Flood in BROWN, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: SPRINGFIELD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.

Flood in NICOLLET, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: COURTLAND
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.

Flood in LE SUEUR, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: KASOTA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.

Flash Flood in LE SUEUR, MINNESOTA
From 23-SEP-10 03:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: LEXINGTON
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Periods of heavy rainfall developed toward midnight, and continued through most of the early morning hours.  Rainfall rates increased to over 1.5 inches per hour which caused flash flooding. Several county roads were inundated by water, along with several streams and creeks that rose rapidly during the morning.

Flash Flood in GOODHUE, MINNESOTA
From 23-SEP-10 03:00:00 to 23-SEP-10 10:00:00 (CST-6)
Location: RANDOLPH
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Periods of heavy rainfall developed toward midnight, and continued through most of the early morning hours.  Rainfall rates increased to over 1.5 inches per hour which caused flash flooding. Numerous county and highway roads were inundated by flood waters, and streams and creeks rose rapidly during the morning. By 5 am, several major highways were closed due to flooded roadways, including Highway 52 from Highway 60 to Goodhue County Road 11 near Pine Island, Highway 60 west of Kenyon, and Highway 60 east of Kenyon between Highway 56 and Goodhue County Road 1.  By 7 am, Northbound Highway 52 from Highway 60 to Goodhue County Road 11 was closed due to flood waters. Then by 9 am, Highway 58 north of Zumbrota was closed.  Other county roads were closed along Highway 60 near Bombay.  County Road 3 in Pine Island closed due to flood waters. The flood waters also caused a Grocery Store in Pine Island to close down.

Flood in STEELE, MINNESOTA
From 23-SEP-10 09:00:00 to 25-SEP-10 21:00:00 (CST-6)
Location: ELLENDALE
Flood cause: Heavy Rain
Property damage: 28.40M
Crop damage: 0.00K
Reported by: County Official

Numerous roads were closed due to excessive rainfall that fell on September 22nd and 23th.  The major areal flooding didn't recede until late Saturday when most of the small streams and creeks had crested and only mainstem rivers remained flooded.  Residents in Owatonna, Minnesota, were fighting to save their homes along the flooded Maple Creek. 70 homes were evacuated in Owatonna due to the rising flood waters. Friday morning was the first time that I-35 was closed due to flood waters south of Owatonna. It re-opened during the afternoon as waters started to recede.

Flash Flood in WASECA, MINNESOTA
From 23-SEP-10 02:30:00 to 23-SEP-10 09:00:00 (CST-6)
Location: WALDORF
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Bands of thunderstorms began to develop across the county by the late evening, with several thunderstorms training over the same areas. By early morning, nearly five inches of rain fell across the southern part of the county.  By morning, several roads were closed or covered with water.  Highway 83 north of Waldorf was closed in both directions.  Highway 13 south of Waseca had single lane traffic due to flooded roadways.

Flash Flood in BLUE EARTH, MINNESOTA
From 23-SEP-10 00:00:00 to 23-SEP-10 09:00:00 (CST-6)
Location: MINNESOTA LAKE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Bands of thunderstorms began to develop across the county by mid evening, with several thunderstorms training over the same areas. By midnight, nearly five inches of rain fell in the southwest corner around Willow Creek and Amboy.  By morning, Amboy had nearly 9 inches of rainfall, with roads closed across the southern part of the county.  In addition, several county roads and highways were closed or blocked by flood waters, including Highway 30 west of Mapleton, and Highway 30 east of Mapleton by County Road 14.  Highway 66 south of Mankato also had water over the road.