A weak cold front entered the state during night of the 2nd into the early morning hours of the 3rd.  The airmass became unstable ahead of the front, though not as unstable as is typically the case in early August.  CAPE values were in the 2000 to 4000 J/kg range with lifted indices around -6 C.  Precipitable water values were generally three quarters of an inch to one inch.  During the day temperatures warmed into the 80s with dew points generally in the upper 50s to mid 60s.  Dew points pooled just ahead of the front and were between 65 and 70.  The freezing level was quite high, between 14,500 and 15,000 feet.  Thunderstorms developed over southeast South Dakota and northwest Iowa during the evening.  They moved southeast and accelerated to around 50 MPH during the late night and early morning hours.  Many of the storms produced hail, however hail was generally around an inch or less in diameter.  One and one quarter inch diameter hail fell in Clarke County, northeast of Osceola.  One of the stronger clusters of storms produced quarter to golf fall size hail in a swath from Schleswig to Denison in Crawford County.  The hail stripped leaves from trees and caused extensive crop damage.  Strong winds were produced as the storms moved into the northwest part of the Des Moines CWA.  Considerable tree and power line damage occurred in Pocahontas, Humboldt, Webster, and Carroll Counties.  Reports indicated that power was knocked out to about 10,000 homes.  As the storms moved through Story County, lightning struck a house northeast of Nevada.  A power pole was struck and the power line was on the house.  A fire resulted causing some damage to the home.

Hail in GUTHRIE, IOWA
From 03-AUG-09 03:42:00 to 03-AUG-09 03:42:00 (CST-6)
Location: BAYARD
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Hail in CARROLL, IOWA
From 03-AUG-09 02:31:00 to 03-AUG-09 02:31:00 (CST-6)
Location: ARCADIA
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Heavy rain, quarter size hail, and strong wind.

Hail in CLARKE, IOWA
From 03-AUG-09 05:33:00 to 03-AUG-09 05:33:00 (CST-6)
Location: WOODBURN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in CRAWFORD, IOWA
From 03-AUG-09 02:07:00 to 03-AUG-09 02:07:00 (CST-6)
Location: SCHLESWIG
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 10.00K
Reported by: Law Enforcement

Hail in CARROLL, IOWA
From 03-AUG-09 01:35:00 to 03-AUG-09 01:35:00 (CST-6)
Location: BREDA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: Fire Department/Rescue

Hail in DALLAS, IOWA
From 03-AUG-09 03:58:00 to 03-AUG-09 03:58:00 (CST-6)
Location: LINDEN
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Hail in CLARKE, IOWA
From 03-AUG-09 05:20:00 to 03-AUG-09 05:20:00 (CST-6)
Location: OSCEOLA
Magnitude: 1.25 
Property damage: 5.00K
Crop damage: 15.00K
Reported by: Trained Spotter

Thunderstorm Wind in HAMILTON, IOWA
From 03-AUG-09 01:10:00 to 03-AUG-09 01:10:00 (CST-6)
Location: WILLIAMS
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Lightning in STORY, IOWA
From 03-AUG-09 03:21:00 to 03-AUG-09 03:21:00 (CST-6)
Location: COLO
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in HUMBOLDT, IOWA
From 02-AUG-09 23:48:00 to 02-AUG-09 23:48:00 (CST-6)
Location: GILMORE
Magnitude: 60.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reported a 60 MPH wind gust.

Hail in BOONE, IOWA
From 03-AUG-09 02:32:00 to 03-AUG-09 02:32:00 (CST-6)
Location: BERKLEY
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Thunderstorm Wind in CARROLL, IOWA
From 03-AUG-09 00:15:00 to 03-AUG-09 00:15:00 (CST-6)
Location: CARROLL
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in WEBSTER, IOWA
From 03-AUG-09 00:00:00 to 03-AUG-09 00:00:00 (CST-6)
Location: CLARE
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trees 2 feet in diameter were blown down.

Thunderstorm Wind in HUMBOLDT, IOWA
From 03-AUG-09 00:10:00 to 03-AUG-09 00:10:00 (CST-6)
Location: DAKOTA CITY
Magnitude: 50.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Large trees were blown down on a house.

Thunderstorm Wind in POCAHONTAS, IOWA
From 02-AUG-09 23:45:00 to 02-AUG-09 23:45:00 (CST-6)
Location: ROLFE
Magnitude: 61.00 EG
Property damage: 25.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Trees down in Rolfe and in Pocahontas.  Twelve inch or larger tree limbs down in Rolfe.  A sliding door was blown off of building that stores semi trucks.

Thunderstorm Wind in WEBSTER, IOWA
From 03-AUG-09 00:05:00 to 03-AUG-09 00:05:00 (CST-6)
Location: FT DODGE
Magnitude: 57.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Large trees and power lines were blown down in town.

Hail in CRAWFORD, IOWA
From 03-AUG-09 02:20:00 to 03-AUG-09 02:45:00 (CST-6)
Location: SCHLESWIG
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 1.00M
Reported by: Newspaper

Hail swath of quarter to golf ball size hail.

Thunderstorm Wind in WEBSTER, IOWA
From 02-AUG-09 23:59:00 to 02-AUG-09 23:59:00 (CST-6)
Location: CLARE
Magnitude: 60.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tree branches were blown down.

Thunderstorm Wind in WEBSTER, IOWA
From 03-AUG-09 00:15:00 to 03-AUG-09 00:15:00 (CST-6)
Location: DUNCOMBE
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Large trees were blown down in town.