A cold front advanced toward Iowa from the northwest during the evening hours of the 1st.  The cold front by late evening extended from southern Nebraska, across far northwest Iowa, into northwest Wisconsin.  Ahead of the front the airmass was quite unstable, albeit quite warm.  Temperatures at the 700 mb level were around +12 C. with the freezing level approaching 16,000 feet.  Lifted indices were around -6 C.  The LCL was quite high, around 2000 meters, which limited the threat of tornadoes.  With the warm temperatures aloft, hail was also limited.  Severe thunderstorm were able to form and maintain themselves as the shear environment was favorable with zero to 3 km shear in the 30 to 40 kt range.  Precipitable water values were approaching 2 inches, so the airmass was quite tropical in nature with the warm cloud depth nearly 4 kms.  Temperatures in the afternoon warmed into the upper 80s to low 90s, combined with dew point values in the mid 70s.  This provided approximately 3000 J/kg of CAPE.  There was a significant amount of downdraft CAPE available with DCAPE values around 1100 J/kg during the early evening.  Thunderstorms developed during the late afternoon and evening hours and produced heavy rain and some high winds.  A 62 MPH wind gust was recorded at the Denison AWOS station and high winds blew a semi-tractortrailer over in Interstate 35 in Cerro Gordo County.  Widespread wind damage was reported across Worth and Franklin Counties.  Winds estimated up to 70 MPH buffeted these two areas as what appears to be a large scale collapse took place.  Much of the high wind occurred as a result of wet microbursts.  High winds hit in the Callender area of Webster County.  The winds caused structural damage and caused $100,000 damage to a grain elevator.  The storms produced very heavy rainfall over northwest Iowa.  Just west of Estherville, 4.75 inches of rain was reported.  In the Algona area, 7.2 inches of rain fell in a little over 3 hours time.  Flash flooding was reported in Emmet and Kossuth Counties with water 2 to 3 feet deep on the highways.  U.S. Highway 169 was closed in Kossuth County by 2 foot deep water.

Thunderstorm Wind in EMMET, IOWA
From 01-AUG-06 19:00:00 to 01-AUG-06 19:00:00 (CST)
Location: ESTHERVILLE
Magnitude: 52 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in PALO ALTO, IOWA
From 01-AUG-06 20:19:00 to 01-AUG-06 20:19:00 (CST)
Location: AYRSHIRE
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in POCAHONTAS, IOWA
From 01-AUG-06 20:45:00 to 01-AUG-06 20:45:00 (CST)
Location: LAURENS
Magnitude: 52 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in KOSSUTH, IOWA
From 01-AUG-06 21:25:00 to 01-AUG-06 21:25:00 (CST)
Location: ALGONA
Magnitude: 57 EG
Property damage: 15K
Reported by: AMATEUR RADIO

Flash Flood in KOSSUTH, IOWA
From 01-AUG-06 20:30:00 to 02-AUG-06 03:00:00 (CST)
Location: ALGONA
Property damage: 100K
Crop damage: 10K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in WORTH, IOWA
From 01-AUG-06 21:45:00 to 01-AUG-06 22:15:00 (CST)
Location: COUNTYWIDE
Magnitude: 61 EG
Property damage: 50K
Crop damage: 5K
Reported by: BROADCAST MEDIA

Flash Flood in EMMET, IOWA
From 01-AUG-06 21:30:00 to 02-AUG-06 02:00:00 (CST)
Location: ESTHERVILLE
Property damage: 25K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CRAWFORD, IOWA
From 01-AUG-06 21:55:00 to 01-AUG-06 21:55:00 (CST)
Location: DENISON MUNI ARPT
Magnitude: 54 MG
Property damage: 5K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in CERRO GORDO, IOWA
From 01-AUG-06 22:40:00 to 01-AUG-06 22:40:00 (CST)
Location: MASON CITY
Magnitude: 61 EG
Property damage: 25K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in WEBSTER, IOWA
From 01-AUG-06 23:05:00 to 01-AUG-06 23:05:00 (CST)
Location: OTHO
Magnitude: 61 EG
Property damage: 50K
Crop damage: 15K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in HAMILTON, IOWA
From 01-AUG-06 23:30:00 to 01-AUG-06 23:30:00 (CST)
Location: WEBSTER CITY
Magnitude: 61 EG
Property damage: 15K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in CERRO GORDO, IOWA
From 01-AUG-06 23:30:00 to 02-AUG-06 00:30:00 (CST)
Location: COUNTYWIDE
Magnitude: 61 EG
Property damage: 50K
Crop damage: 10K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in FRANKLIN, IOWA
From 02-AUG-06 00:07:00 to 02-AUG-06 00:07:00 (CST)
Location: LATIMER
Magnitude: 52 MG
Property damage: 5K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in FRANKLIN, IOWA
From 02-AUG-06 00:30:00 to 02-AUG-06 00:30:00 (CST)
Location: HAMPTON
Magnitude: 52 EG
Property damage: 5K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in WEBSTER, IOWA
From 01-AUG-06 23:35:00 to 01-AUG-06 23:35:00 (CST)
Location: CALLENDER
Magnitude: 70 EG
Property damage: 100K
Crop damage: 10K
Reported by: NEWSPAPER