A cold front had moved south of Iowa during the afternoon and evening of the 4th, however the airmass in the vicinity of the front was capped.  It remained very unstable over Iowa with CAPE in the 3000-5000 J/kg range and lifted indices from -7 to -11 C.  There was considerable downdraft CAPE available with values around 1300 J/kg.  CAPE in the -10 to -30 C. layer was quite high in the 900 to 1200 J/kg range.  This was plenty to overcome the high freezing level of 15,200 feet.  The atmosphere was quite strongly sheared for early August with 40 to 45 kts of shear.  Deep moisture was also in place with a little over 2 inches of precipitable water present.  A small area of thunderstorms erupted rapidly shortly before midnight from west central toward central Iowa.  They became severe in central Iowa and advanced east across the state.  The storms produced penny to quarter size hail at several locations, and smaller hail at numerous locations.  Within a relatively short time of the storms becoming severe, under an hour, they began to produce high winds.  Scattered gusts of 60 to 65 MPH were reported from Polk County to Mahaska County.  Some tree damage occurred with the winds.  Two power poles were blown over in Marion County near Harvey and an outbuilding was toppled near Pella.

Thunderstorm Wind in POLK, IOWA
From 04-AUG-08 23:44:00 to 04-AUG-08 23:44:00 (CST-6)
Location: FT DES MOINES
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in WARREN, IOWA
From 05-AUG-08 00:10:00 to 05-AUG-08 00:10:00 (CST-6)
Location: HARTFORD
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported 60 MPH wind gust and pea size hail east of Hartford.

Hail in DALLAS, IOWA
From 04-AUG-08 23:27:00 to 04-AUG-08 23:27:00 (CST-6)
Location: ADEL
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 10.00K
Reported by: NWS Employee

Hail in POLK, IOWA
From 04-AUG-08 23:31:00 to 04-AUG-08 23:31:00 (CST-6)
Location: ASHAWA
Magnitude: 0.88 
Property damage: 2.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Hail in WARREN, IOWA
From 04-AUG-08 23:55:00 to 04-AUG-08 23:55:00 (CST-6)
Location: CLARKSON
Magnitude: 0.88 
Property damage: 2.00K
Crop damage: 5.00K
Reported by: Law Enforcement

Law Enforcement reported nickel size hail and wind gusts to 50 MPH in the town of Carlisle.

Hail in POLK, IOWA
From 04-AUG-08 23:34:00 to 04-AUG-08 23:34:00 (CST-6)
Location: CLOVER HILLS
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported nickel to quarter size hail falling in West Des Moines.

Hail in POLK, IOWA
From 04-AUG-08 23:44:00 to 04-AUG-08 23:44:00 (CST-6)
Location: FT DES MOINES
Magnitude: 0.88 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

Public reported penny to nickel size hail in southeast Des Moines.

Hail in POLK, IOWA
From 04-AUG-08 23:36:00 to 04-AUG-08 23:38:00 (CST-6)
Location: WINDSOR HGTS
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: NWS Employee

Most of the hail was pea size with a few stones up to an inch in diameter.

Hail in POLK, IOWA
From 04-AUG-08 23:45:00 to 04-AUG-08 23:45:00 (CST-6)
Location: DES MOINES
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Thunderstorm Wind in MARION, IOWA
From 05-AUG-08 00:35:00 to 05-AUG-08 00:35:00 (CST-6)
Location: PELLA MUNI ARPT
Magnitude: 57.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Emergency Manager

An outbuilding was blown over by high winds.

Thunderstorm Wind in MARION, IOWA
From 05-AUG-08 00:37:00 to 05-AUG-08 00:37:00 (CST-6)
Location: HARVEY
Magnitude: 57.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A few 6 to 10 inch tree limbs were blown down and two power poles were blown down.

Thunderstorm Wind in MAHASKA, IOWA
From 05-AUG-08 01:00:00 to 05-AUG-08 01:00:00 (CST-6)
Location: UNIVERSITY PARK
Magnitude: 56.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in MARION, IOWA
From 05-AUG-08 00:33:00 to 05-AUG-08 00:33:00 (CST-6)
Location: FLAGLER
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Large tree branches were blown down.

Hail in DALLAS, IOWA
From 04-AUG-08 23:20:00 to 04-AUG-08 23:20:00 (CST-6)
Location: HADDEN HILL
Magnitude: 0.88 
Property damage: 2.00K
Crop damage: 5.00K
Reported by: Law Enforcement

Law Enforcement reported dime to nickel size hail in Waukee.

Hail in DALLAS, IOWA
From 04-AUG-08 23:19:00 to 04-AUG-08 23:24:00 (CST-6)
Location: HADDEN HILL
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Penny size hail fell for 5 minutes.

Hail in DALLAS, IOWA
From 04-AUG-08 23:19:00 to 04-AUG-08 23:19:00 (CST-6)
Location: SHULER MINE
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 10.00K
Reported by: NWS Employee

Hail in POLK, IOWA
From 04-AUG-08 23:48:00 to 04-AUG-08 23:48:00 (CST-6)
Location: FT DES MOINES
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported nickel to quarter size hail at Wal-mart on southeast 14th Street.