A weak frontal boundary extending from northwest Minnesota into southwest Kansas advanced toward Iowa.  The flow was very week, but the airmass was very moist.  Precipitable water values were above 2 inches with a deep warm layer in place.  The freezing level was between 14,500 and 15,500 feet.  The CAPE in the -10 to -30 layer was significant at 800 J/kg, but in spite of that there was little hail due to the very high freezing level.  Afternoon temperatures warmed in to the upper 80s to low 90s with dew points in the mid 70s.  This pushed the most unstable CAPE to around 5500 J/kg.  Lifted indices were in the -9 to -11 range by late afternoon.  Tornadoes did not occur with a weak shear environment (under 20 kts) and with an LCL of 1000 to 1200 meters.  There was a fair amount of DCAPE available, about 1500 J/kg.  Thunderstorms formed in three areas as the afternoon progressed.  One area was in northwest Iowa, with the second over eastern Nebraska moving into west central and southwest Iowa.  The third area was smaller with development over the southeast counties of the state.  Initially the storms produced some marginally severe half of three quarter to one inch in diameter.  As the afternoon progressed, the two clusters in northwest and southwest Iowa merged, and the storms over the southeast weakened.  The systems over the west took on more of a linear structure and the event transitioned into a wind event.  There were several reports of trees and power lines downed by the high winds.  The strongest winds was measured at 75 MPH in Adair.

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:25:00 to 13-JUL-06 17:25:00 (CST)
Location: WEST DES MOINES
Magnitude: 52 EG
Property damage: 2K
Reported by: STORM CHASER

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:15:00 to 13-JUL-06 17:15:00 (CST)
Location: CLIVE
Magnitude: 52 EG
Property damage: 5K
Reported by: NWS EMPLOYEE(OFF DUTY)

Thunderstorm Wind in DECATUR, IOWA
From 13-JUL-06 18:08:00 to 13-JUL-06 18:08:00 (CST)
Location: LEON
Magnitude: 55 MG
Property damage: 5K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in LUCAS, IOWA
From 13-JUL-06 18:05:00 to 13-JUL-06 18:05:00 (CST)
Location: DERBY
Magnitude: 50 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:20:00 to 13-JUL-06 17:20:00 (CST)
Location: DES MOINES
Magnitude: 52 EG
Property damage: 5K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in UNION, IOWA
From 13-JUL-06 17:50:00 to 13-JUL-06 17:50:00 (CST)
Location: CRESTON ARPT
Magnitude: 51 MG
Property damage: 2K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in WARREN, IOWA
From 13-JUL-06 17:20:00 to 13-JUL-06 17:20:00 (CST)
Location: CARLISLE
Magnitude: 52 MG
Property damage: 3K
Reported by: AMATEUR RADIO

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:20:00 to 13-JUL-06 17:20:00 (CST)
Location: DES MOINES
Magnitude: 50 EG
Property damage: 2K
Reported by: NWS EMPLOYEE(OFF DUTY)

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:18:00 to 13-JUL-06 17:18:00 (CST)
Location: WINDSOR HGTS
Magnitude: 58 MG
Property damage: 3K
Reported by: NWS EMPLOYEE(OFF DUTY)

Thunderstorm Wind in AUDUBON, IOWA
From 13-JUL-06 16:45:00 to 13-JUL-06 16:45:00 (CST)
Location: AUDUBON
Magnitude: 50 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in GUTHRIE, IOWA
From 13-JUL-06 17:08:00 to 13-JUL-06 17:08:00 (CST)
Location: CASEY
Magnitude: 50 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:15:00 to 13-JUL-06 17:15:00 (CST)
Location: URBANDALE
Magnitude: 50 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in ADAIR, IOWA
From 13-JUL-06 17:02:00 to 13-JUL-06 17:02:00 (CST)
Location: ADAIR
Magnitude: 65 MG
Property damage: 10K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:19:00 to 13-JUL-06 17:19:00 (CST)
Location: WEST DES MOINES
Magnitude: 50 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in ADAIR, IOWA
From 13-JUL-06 17:18:00 to 13-JUL-06 17:18:00 (CST)
Location: GREENFIELD
Magnitude: 50 EG
Property damage: 2K
Reported by: AMATEUR RADIO

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:14:00 to 13-JUL-06 17:14:00 (CST)
Location: URBANDALE
Magnitude: 52 EG
Property damage: 2K
Reported by: AMATEUR RADIO

Hail in WARREN, IOWA
From 13-JUL-06 16:39:00 to 13-JUL-06 16:39:00 (CST)
Location: ST MARYS
Magnitude: 0.88 
Property damage: 2K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in DALLAS, IOWA
From 13-JUL-06 16:52:00 to 13-JUL-06 16:52:00 (CST)
Location: MINBURN
Magnitude: 57 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in AUDUBON, IOWA
From 13-JUL-06 16:38:00 to 13-JUL-06 16:38:00 (CST)
Location: AUDUBON
Magnitude: 50 MG
Property damage: 2K
Reported by: AWOS,ASOS,MESONET,ETC

Hail in WARREN, IOWA
From 13-JUL-06 16:25:00 to 13-JUL-06 16:25:00 (CST)
Location: INDIANOLA
Magnitude: 1.00 
Property damage: 5K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in CRAWFORD, IOWA
From 13-JUL-06 16:26:00 to 13-JUL-06 16:26:00 (CST)
Location: VAIL
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in CRAWFORD, IOWA
From 13-JUL-06 15:44:00 to 13-JUL-06 15:44:00 (CST)
Location: BUCK GROVE
Magnitude: 0.75 
Crop damage: 5K
Reported by: GENERAL PUBLIC

Thunderstorm Wind in POLK, IOWA
From 13-JUL-06 17:14:00 to 13-JUL-06 17:14:00 (CST)
Location: URBANDALE
Magnitude: 52 EG
Property damage: 2K
Reported by: NWS EMPLOYEE(OFF DUTY)

Hail in STORY, IOWA
From 13-JUL-06 16:55:00 to 13-JUL-06 16:55:00 (CST)
Location: HUXLEY
Magnitude: 0.75 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in POLK, IOWA
From 13-JUL-06 17:09:00 to 13-JUL-06 17:09:00 (CST)
Location: GRIMES
Magnitude: 0.52 
Property damage: 2K
Reported by: NWS STORM SURVEY

Thunderstorm Wind in CRAWFORD, IOWA
From 13-JUL-06 14:33:00 to 13-JUL-06 14:33:00 (CST)
Location: VAIL
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in CRAWFORD, IOWA
From 13-JUL-06 15:43:00 to 13-JUL-06 15:43:00 (CST)
Location: VAIL
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER