Very warm and humid air was in place over Iowa during the 30th and the 1st with high temperatures in the 90s and dew points in the mid 70s to low 80s.  The airmass was capped on the 30th, and remained fairly capped on the evening of the 1st as a cold front moves southeast into the state.  The cap weakened first over northern Iowa and then gradually farther to the south as the night progressed.  The freezing level was quite high, in the 14,500 to 15,000 foot range.  In spite of CAPE values in the -10 to -30 C layer of the atmosphere in the 400 to 700 J/kg range, hail production was limited with only spot reports of golf ball to ping pong ball size hail. Precipitable water increased to around 1.5 inches during the evening.  CAPE was around 4000 J/kg, with the lifted index around -10 C.  A narrow line of thunderstorms formed along the cold front with the main mode of severe weather being high winds.  Downdraft CAPE was high, around 1500 J/kg.  This resulted in wind of 60 to 70 MPH at several locations.  The factor against the stronger storm development was the lack of shear, with only 20 kts available.  There were numerous reports of trees and power lines being downed by the high winds.  A boat was blown from a dock into a house in the Clear Lake area.  Windows were also blown out of a house there as well.  Power was knocked out to about 1000 customers in the Mason City, Clear Lake Area.

Hail in CERRO GORDO, IOWA
From 01-JUL-11 21:08:00 to 01-JUL-11 21:08:00 (CST-6)
Location: MASON CITY
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Hail in GUTHRIE, IOWA
From 01-JUL-11 21:40:00 to 01-JUL-11 21:40:00 (CST-6)
Location: MONTEITH
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 10.00K
Reported by: Public

Hail in HAMILTON, IOWA
From 01-JUL-11 21:43:00 to 01-JUL-11 21:43:00 (CST-6)
Location: JEWELL
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 10.00K
Reported by: Law Enforcement

An officer estimated quarter size hail.

Thunderstorm Wind in WINNEBAGO, IOWA
From 01-JUL-11 20:00:00 to 01-JUL-11 20:00:00 (CST-6)
Location: THOMPSON
Magnitude: 57.00 EG
Property damage: 25.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Numerous trees down from Thompson to Lake Mills to Scarville.

Thunderstorm Wind in WEBSTER, IOWA
From 01-JUL-11 20:26:00 to 01-JUL-11 20:26:00 (CST-6)
Location: OTHO
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

One foot diameter trees were downed.

Thunderstorm Wind in CERRO GORDO, IOWA
From 01-JUL-11 20:40:00 to 01-JUL-11 20:40:00 (CST-6)
Location: CLEAR LAKE
Magnitude: 61.00 EG
Property damage: 125.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A boat was blown from the dock into a house at the 700 block of South Shore Drive.

Thunderstorm Wind in KOSSUTH, IOWA
From 01-JUL-11 19:10:00 to 01-JUL-11 19:10:00 (CST-6)
Location: SWEA CITY
Magnitude: 57.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency Manager reported several trees down in town by estimated winds of 60 to 70 MPH.

Thunderstorm Wind in CERRO GORDO, IOWA
From 01-JUL-11 20:40:00 to 01-JUL-11 20:40:00 (CST-6)
Location: CLEAR LAKE
Magnitude: 57.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Two power lines were down and tree branches down.  Reported by KGLO AM Radio.

Thunderstorm Wind in CERRO GORDO, IOWA
From 01-JUL-11 20:40:00 to 01-JUL-11 20:40:00 (CST-6)
Location: CLEAR LAKE
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Windows were blown out of a house.  Relayed by WHO TV.

Thunderstorm Wind in SAC, IOWA
From 01-JUL-11 18:20:00 to 01-JUL-11 18:20:00 (CST-6)
Location: LAKE VIEW
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A large branch fell onto a car causing significant damage.

Thunderstorm Wind in WORTH, IOWA
From 01-JUL-11 20:16:00 to 01-JUL-11 20:16:00 (CST-6)
Location: NORTHWOOD
Magnitude: 57.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Numerous trees down on power lines.

Thunderstorm Wind in FRANKLIN, IOWA
From 01-JUL-11 21:20:00 to 01-JUL-11 21:20:00 (CST-6)
Location: HAMPTON
Magnitude: 57.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Numerous tree limbs down.  Road department had to clear the roads.

Thunderstorm Wind in GUTHRIE, IOWA
From 01-JUL-11 21:50:00 to 01-JUL-11 21:50:00 (CST-6)
Location: HERNDON
Magnitude: 52.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: NWS Employee

Large tree limbs down, one causing damage to porch.

Thunderstorm Wind in EMMET, IOWA
From 01-JUL-11 18:20:00 to 01-JUL-11 18:20:00 (CST-6)
Location: MAPLE HILL
Magnitude: 57.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Several 4 to 6 inch diameter large tree branches were blown down.  Small hail also accompanied the storm.

Hail in CRAWFORD, IOWA
From 01-JUL-11 17:55:00 to 01-JUL-11 17:55:00 (CST-6)
Location: DELOIT
Magnitude: 1.75 
Property damage: 20.00K
Crop damage: 10.00K
Reported by: Law Enforcement

Hail in CALHOUN, IOWA
From 01-JUL-11 18:45:00 to 01-JUL-11 18:45:00 (CST-6)
Location: YETTER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 10.00K
Reported by: Trained Spotter

A trained spotter reported dime to nickel size hail.

Hail in CALHOUN, IOWA
From 01-JUL-11 20:03:00 to 01-JUL-11 20:03:00 (CST-6)
Location: LOHRVILLE
Magnitude: 0.88 
Property damage: 3.00K
Crop damage: 10.00K
Reported by: Law Enforcement

Nickel size hail was reported along with 40 to 50 MPH winds.

Hail in WINNEBAGO, IOWA
From 01-JUL-11 20:00:00 to 01-JUL-11 20:00:00 (CST-6)
Location: LAKE MILLS
Magnitude: 1.50 
Property damage: 15.00K
Crop damage: 10.00K
Reported by: Emergency Manager

Thunderstorm Wind in HAMILTON, IOWA
From 01-JUL-11 20:50:00 to 01-JUL-11 20:50:00 (CST-6)
Location: WEBSTER CITY
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reported multiple large tree branches down in town.

Thunderstorm Wind in DALLAS, IOWA
From 01-JUL-11 22:19:00 to 01-JUL-11 22:19:00 (CST-6)
Location: PERRY
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Nickel hail with 4 to 6 inch tree limbs blown down across town.

Thunderstorm Wind in FRANKLIN, IOWA
From 01-JUL-11 21:15:00 to 01-JUL-11 21:15:00 (CST-6)
Location: LATIMER
Magnitude: 57.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Numerous 4 to 8 inch diameter tree branches were blown down.

Thunderstorm Wind in GRUNDY, IOWA
From 01-JUL-11 22:29:00 to 01-JUL-11 22:29:00 (CST-6)
Location: WELLSBURG
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Fire department estimated winds of 60 MPH.

Thunderstorm Wind in POCAHONTAS, IOWA
From 01-JUL-11 19:20:00 to 01-JUL-11 19:20:00 (CST-6)
Location: ROLFE
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trees of 12 inches in diameter were blown down.