An unstable airmass was located over Iowa.  A cold front moved into the western part of the state during the afternoon.  Thunderstorms erupted around mid day and tracked east across the southern and eastern part of the state.  Though CAPE rose to 4000-5000 J/kg and the lifted index fell to between -7 and -9 C, severe weather was limited.  Gusty winds occurred, along with some small hail, but the most significant event was the heavy rainfall.  Precipitable water values increased to between 1.8 and 2.3 inches by early afternoon.  The storms became efficient rainfall producers.  In Madison County, nearly 2 inches of rain fell in a two hour period.  The storms were more intense as they moved through the Ottumwa area in Wapello County.  Rainfall of 4-5 inches occurred in the Ottumwa area.  In just over an hour, 4.2 inches fell at the Ottumwa Airport.  Flooding occurred very quickly along U.S. Highway 63 as shown in a photo.  The photo was taken a little over an hour after the heavy rain began with water 5 feet deep over the highway.  The water eventually reached a depth of 20 feet over the highway.  Flash flooding occurred north and east of the city of Ottumwa.  Roads were close by flowing water as deep as car windows in places.  Rapidly rising water required that a daycare center on the north side of Ottumwa be evacuated.  As the thunderstorms continued to move eastward, thunderstorms produced strong winds in the Pulaski area.  A storage facility was damaged in town.

Heavy Rain in MADISON, IOWA
From 20-AUG-10 10:30:00 to 20-AUG-10 12:55:00 (CST-6)
Location: WINTERSET ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rainfall of 1.8 inches was measured since 1030 CDT.

Heavy Rain in WAPELLO, IOWA
From 20-AUG-10 14:30:00 to 20-AUG-10 15:35:00 (CST-6)
Location: (OTM)OTTUMWA INDSTRL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Rainfall at the Ottumwa airport was measured at 4.2 inches within just over an hours time.

Flash Flood in WAPELLO, IOWA
From 20-AUG-10 15:24:00 to 20-AUG-10 21:00:00 (CST-6)
Location: DAHLONEGA
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Local law enforcement and trained spotters report water flowing over Highway 149 and North Court Road in the 2600 to 2700 block on the north side of Ottumwa.  Water was up to the windows of cars with vehicles stalling and traffic backing up.

Flash Flood in WAPELLO, IOWA
From 20-AUG-10 15:30:00 to 20-AUG-10 21:00:00 (CST-6)
Location: (OTM)OTTUMWA INDSTRL
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports water flowing over the road near the intersection of Angle Road and Highway 149 in north Ottumwa.

Thunderstorm Wind in DAVIS, IOWA
From 20-AUG-10 15:50:00 to 20-AUG-10 15:50:00 (CST-6)
Location: PULASKI
Magnitude: 52.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Newspaper

A storage facility was damaged by thunderstorms winds.

Flash Flood in WAPELLO, IOWA
From 20-AUG-10 15:22:00 to 20-AUG-10 21:00:00 (CST-6)
Location: OTTUMWA
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reports water flowing over the road and blocking traffic near the intersection of Pennsylvania Ave and Jefferson Street.

Heavy Rain in WAPELLO, IOWA
From 20-AUG-10 14:00:00 to 20-AUG-10 18:00:00 (CST-6)
Location: (OTM)OTTUMWA INDSTRL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Rainfall total was 4.54 inches.

Flash Flood in WAPELLO, IOWA
From 20-AUG-10 20:14:00 to 20-AUG-10 21:00:00 (CST-6)
Location: (OTM)OTTUMWA INDSTRL
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Local law enforcement reports water from the Little Cedar Creek rushing over Angle Road just east of Highway 149 on the north side of Ottumwa.

Flash Flood in WAPELLO, IOWA
From 20-AUG-10 15:50:00 to 20-AUG-10 21:00:00 (CST-6)
Location: OTTUMWA
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Six inches of flowing water across Eddyville Road.  Cars stalled.

Flash Flood in WAPELLO, IOWA
From 20-AUG-10 14:45:00 to 20-AUG-10 21:00:00 (CST-6)
Location: (OTM)OTTUMWA INDSTRL
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Newspaper

Friday���s heavy rain caused water to come up rapidly on U.S. Highway 63, just north of Ottumwa and before Angle Road.