Iowa remained in a northwest flow with numerous short waves embedded in the flow.  A mid level cap was in place over southwest Iowa and areas southwest, limiting the formation of thunderstorms.  The airmass was very unstable with lifted indices in the -12 C. range and CAPE values between 5000 and 6000 J/kg.  Surface dew point readings were in the mid 70s well into the night.  Thunderstorms erupted over northwest Iowa during the early morning hours.  They became severe quite quickly and tracked southeast across the state.  The storms produced hail of up to golf ball size in Greene County as well as Boone County.   As the storms progressed southeast, they began to become wind producers.  Wind gusts around 60 MPH were reported in parts of central and southeast Iowa with spotty tree and power line damage occurring.

Hail in MARION, IOWA
From 03-AUG-04 04:10:00 to 03-AUG-04 04:10:00 (CST)
Location: PLEASANTVILLE
Magnitude: 1.75 
Property damage: 15K
Crop damage: 5K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in MARION, IOWA
From 03-AUG-04 04:20:00 to 03-AUG-04 04:20:00 (CST)
Location: KNOXVILLE
Magnitude: 50 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Hail in GREENE, IOWA
From 03-AUG-04 01:06:00 to 03-AUG-04 01:06:00 (CST)
Location: CHURDAN
Magnitude: 1.75 
Property damage: 10K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in MARION, IOWA
From 03-AUG-04 04:21:00 to 03-AUG-04 04:21:00 (CST)
Location: KNOXVILLE ARPT
Magnitude: 50 MG
Property damage: 1K
Reported by: AWOS,ASOS,MESONET,ETC

Hail in GREENE, IOWA
From 03-AUG-04 00:31:00 to 03-AUG-04 00:31:00 (CST)
Location: CHURDAN
Magnitude: 0.75 
Crop damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in POLK, IOWA
From 03-AUG-04 03:45:00 to 03-AUG-04 03:45:00 (CST)
Location: RUNNELLS
Magnitude: 57 EG
Property damage: 5K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in POLK, IOWA
From 03-AUG-04 03:30:00 to 03-AUG-04 03:30:00 (CST)
Location: ALTOONA
Magnitude: 61 EG
Property damage: 10K
Reported by: GENERAL PUBLIC

Hail in GREENE, IOWA
From 03-AUG-04 01:47:00 to 03-AUG-04 01:47:00 (CST)
Location: PATON
Magnitude: 0.75 
Crop damage: 5K
Reported by: GENERAL PUBLIC

Hail in GREENE, IOWA
From 03-AUG-04 02:05:00 to 03-AUG-04 02:05:00 (CST)
Location: GRAND JCT
Magnitude: 0.75 
Crop damage: 5K
Reported by: GENERAL PUBLIC

Thunderstorm Wind in WAPELLO, IOWA
From 03-AUG-04 06:00:00 to 03-AUG-04 06:00:00 (CST)
Location: OTTUMWA
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MARION, IOWA
From 03-AUG-04 04:21:00 to 03-AUG-04 04:21:00 (CST)
Location: KNOXVILLE
Magnitude: 50 MG
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in POLK, IOWA
From 03-AUG-04 03:02:00 to 03-AUG-04 03:02:00 (CST)
Location: JOHNSTON
Magnitude: 50 MG
Reported by: OFFICIAL NWS OBS.

Hail in BOONE, IOWA
From 03-AUG-04 03:38:00 to 03-AUG-04 03:38:00 (CST)
Location: BOONE
Magnitude: 1.75 
Property damage: 10K
Crop damage: 5K
Reported by: BROADCAST MEDIA

Hail in CALHOUN, IOWA
From 03-AUG-04 02:20:00 to 03-AUG-04 02:20:00 (CST)
Location: FARNHAMVILLE
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in POLK, IOWA
From 03-AUG-04 03:11:00 to 03-AUG-04 03:11:00 (CST)
Location: WEST DES MOINES
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in DAVIS, IOWA
From 03-AUG-04 05:42:00 to 03-AUG-04 05:42:00 (CST)
Location: DRAKESVILLE
Magnitude: 50 EG
Property damage: 1K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in WAPELLO, IOWA
From 03-AUG-04 05:45:00 to 03-AUG-04 05:45:00 (CST)
Location: OTTUMWA
Magnitude: 50 EG
Property damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 03-AUG-04 02:30:00 to 03-AUG-04 02:30:00 (CST)
Location: OGDEN
Magnitude: 61 EG
Property damage: 3K
Crop damage: 5K
Reported by: NEWSPAPER