Very unstable conditions developed during the afternoon of August 20th over eastern Nebraska as a warm front set up from central into southeast Nebraska by early afternoon. Temperatures were in the 90s with dew points in the 70s south of the boundary. A strong upper level disturbance that moved across the state helped trigger thunderstorm development by mid afternoon as it brought a wind shift of drier air eastward to meet the unstable conditions. Severe thunderstorms quickly developed and they congealed into several bow echo type configurations as they tracked across both the Lincoln and Omaha metro areas and then into southwest Iowa. Moderate amounts of wind damage was reported with the activity along with scattered large hail reports.

Thunderstorm Wind in MILLS, IOWA
From 20-AUG-07 19:00:00 to 20-AUG-07 19:00:00 (CST-6)
Location: GLENWOOD
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Thunderstorm winds estimated at over 60 mph downed tree limbs and power lines in town.  A window was blown out of the administrative office of the County Sheriff's Office and a 100 foot section of fencing along a ball field was ripped down.

Funnel Cloud in POTTAWATTAMIE, IOWA
From 20-AUG-07 18:25:00 to 20-AUG-07 18:25:00 (CST-6)
Location: COUNCIL BLUFFS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A funnel cloud was reported by a spotter moving up and down near 29th Street and Avenue G.  The funnel was caught on video and played later on a local tv station.

Thunderstorm Wind in MONTGOMERY, IOWA
From 20-AUG-07 19:40:00 to 20-AUG-07 19:40:00 (CST-6)
Location: RED OAK
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

A thunderstorm wind gust was measured at 61 mph by the AWOS in Red Oak.  The strong winds caused significant tree damage in town.  Fallen trees damaged roofs, vehicles and blocked a few roads.  Other building damage was noted included a crumpled grain bin near town.

Thunderstorm Wind in POTTAWATTAMIE, IOWA
From 20-AUG-07 19:30:00 to 20-AUG-07 19:40:00 (CST-6)
Location: OAKLAND
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm winds estimated at 60 mph downed large tree limbs which caused damage to transformers knocking power out across the southwest part of town.  Other damage that was observed included a porch blown off of a house.

Thunderstorm Wind in MONTGOMERY, IOWA
From 20-AUG-07 20:05:00 to 20-AUG-07 20:20:00 (CST-6)
Location: VILLISCA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm wind gusts estimated at 60 mph knocked down numerous large limbs and several trees which blocked a road and downed power lines.  Power was knocked out over a large section of town.

Hail in SHELBY, IOWA
From 20-AUG-07 19:35:00 to 20-AUG-07 19:35:00 (CST-6)
Location: HARLAN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in POTTAWATTAMIE, IOWA
From 20-AUG-07 18:50:00 to 20-AUG-07 18:50:00 (CST-6)
Location: UNDERWOOD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Thunderstorm winds estimated by a cooperative observer to be 60 mph downed 3 to 4 inch tree limbs.

Thunderstorm Wind in MILLS, IOWA
From 20-AUG-07 19:00:00 to 20-AUG-07 19:00:00 (CST-6)
Location: GLENWOOD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

An amateur radio operator reported damage to shingles northeast of Glenwood.  The damage was caused by thunderstorm winds estimated at 60 mph.

Thunderstorm Wind in PAGE, IOWA
From 20-AUG-07 20:20:00 to 20-AUG-07 20:20:00 (CST-6)
Location: HEPBURN
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm winds estimated at 60 mph knocked down power poles near town.

Thunderstorm Wind in POTTAWATTAMIE, IOWA
From 20-AUG-07 18:46:00 to 20-AUG-07 18:46:00 (CST-6)
Location: COUNCIL BLUFFS
Magnitude: 64.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A local media meteorologist measured a wind gust of 74 mph in Council Bluffs.  The strong winds caused scattered tree damage in town including downed power lines.

Thunderstorm Wind in MILLS, IOWA
From 20-AUG-07 19:05:00 to 20-AUG-07 19:05:00 (CST-6)
Location: MINEOLA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm winds estimated at 60 mph downed a 12 to 15 inch diamter limb onto power lines near town.