A very moist airmass remained in place over Iowa.  Precipitable water values were near 2.25 inches when a wave of low pressure moved northeast along a stalled front to the south of the state.  Thunderstorms enhanced with a narrow line of intense storms setting up across parts of Dallas County into Polk County.  Thunderstorm development was quite rapid and formed on the north edge of a decaying MCS to the southwest.  Additional heavy storms developed and produced heavy rainfall over Story County.  Rainfall of 1 to 2.5 inches in under an hour produced flash flooding.  The flooding took place during rush hour in the Des Moines metropolitan area.  Numerous cars were stalled with many intersections under water.  Rescue missions were conducted in a few locations to get people out of the fast flowing water.  Significant damage occurred near the intersection of Interstate 80 and Merle Hay Road.  Flooding overtook part of the first floor of a hotel there.  On top of the heavy rainfall, water was not able to flow out of the area due to a collapsed storm sewer.    Flowing water was reported 1 to 2 feet in several locations across the north side of Des Moines.  Manhole covers were blown off by rapidly rising water in Dallas County at Adel.  The storms produced 6 to 12 inches of flowing water in parts of Story County as well.

Flash Flood in STORY, IOWA
From 04-AUG-10 07:59:00 to 04-AUG-10 09:30:00 (CST-6)
Location: COLLINS
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Estimated 6 inches of water flowing over the road at the intersection of 4th and 2nd Ave.

Flash Flood in POLK, IOWA
From 04-AUG-10 07:00:00 to 04-AUG-10 09:30:00 (CST-6)
Location: LOVINGTON
Flood cause: Heavy Rain
Property damage: 1.00M
Crop damage: 0.00K
Reported by: NWS Employee

Merle Hay flooded round 0800 with about 2 feet of water over the road.

Flash Flood in DALLAS, IOWA
From 04-AUG-10 06:59:00 to 04-AUG-10 11:45:00 (CST-6)
Location: ADEL
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Manhole covers blown off and cars stalled in several intersections.

Flash Flood in STORY, IOWA
From 04-AUG-10 07:57:00 to 04-AUG-10 09:30:00 (CST-6)
Location: MAXWELL
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Flash flooding reported with water over the road 1/2 mile north of Highway 210 on 670th Ave and 310th Street.

Flash Flood in POLK, IOWA
From 04-AUG-10 06:34:00 to 04-AUG-10 09:30:00 (CST-6)
Location: URBANDALE
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Several vehicles stalled at the intersection of Northwest Urbandale Drive and Meredith Drive, also at Douglas Ave and Aurora Ave by 1 to 1.5 feet of water flowing through the intersections.

Flash Flood in POLK, IOWA
From 04-AUG-10 06:02:00 to 04-AUG-10 09:30:00 (CST-6)
Location: LOVINGTON
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported several stalled vehicles at the intersection of Beaver Drive and Valdez Drive.

Flash Flood in POLK, IOWA
From 04-AUG-10 06:46:00 to 04-AUG-10 09:30:00 (CST-6)
Location: URBANDALE
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager reported tire-deep water flowing down the road at the intersection of 86th and I-80.  Power loss and several vehicles stalled.

Flash Flood in DALLAS, IOWA
From 04-AUG-10 07:42:00 to 04-AUG-10 11:45:00 (CST-6)
Location: DALLAS MINE
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Highway F31 near Beaver Creek is closed, estimated 6-8 inches of water flowing over the road.