An extremely unstable airmass remained in place over Iowa on the afternoon of the 26th.  Low pressure was over southeast South Dakota, with a warm front extending east-southeast into east central Iowa and a cold front extending southwest into northwest Kansas.  A 30 t0 40 kt low level jet feed moisture north ahead of the approaching cold front.  Surface temperatures warmed into the low 90s with dew points in the low to mid 70s across much of the state.  CAPE rose to 5000 to 7000 J/kg ahead of the front with lifted indices of -12 to -15 C.  Strong severe weather parameters were present with downdraft CAPE of 1600-1900 J/kg in the prestorm environment and available CAPE in the -10 to -30 C layer of the atmosphere of 1000-1300 J/kg.  The freezing level was again very high in the 14,500 to 15,000 foot range.  Precipitable water values were somewhat lower than the previous day, though quite high at 1.5 to 1.8 inches.  The LCL was a relatively high 1000-1500 meters.  The environment had fairly strong shear at 50 kts in northern Iowa, and a weaker 30 kts over the south.  A strong cap at 700 mb was present in western Iowa during the mid to late afternoon hours with temperatures above +15 C.  To the west of the cap, along the temperature gradient, strong convection developed by mid to late afternoon over southwest Minnesota, southeast South Dakota, into northeast Nebraska.  Initially the storms lifted northeast ahead of the cold front.  The storms formed into an arc line of storms and progressed east into Iowa.  They weakened and became more multi-cellular as they progressed east.  Several of the storms produced gusty winds and small hail.  A few reports of winds of 60 to 65 MPH were received.  Damage was relatively minor for the most part, with it restricted to tree and large tree limbs.  One storm caused structural damage on a farm in Winnebago County with roof damage to a shed and 4 grain bins destroyed.  Heavy rainfall resulted in some flash flooding.  The storms weakened during the early morning hours.  Shortly before sunrise, the storms strengthened again as the area became cold pool dominated.  Around that time, a wind gust of 70 MPH was recorded at an Iowa RWIS site north of Des Moines, with another gust to 70 MPH measured at an RWIS site in Tama.  High winds caused damage to grain bins and buildings on a farmstead in Marion County.  In Kossuth County, water was flowing over roads southeast of the airport.  In Palo Alto County, flowing water was reported over roads north of Ruthven in a campsite there.  Significant flash flooding took place in the Pomeroy area of Calhoun County.  Major flash flooding took place in Webster County as well with many roads flooded, some by several feet of water, in the city of Fort Dodge.  Thunderstorms moving through central Iowa caused minor urban flooding in Polk County in the Des Moines metro area with a couple of inches of water in intersections and ponding up around a foot deep over roads in low areas.

Thunderstorm Wind in PALO ALTO, IOWA
From 26-JUN-10 20:45:00 to 26-JUN-10 20:45:00 (CST-6)
Location: EMMETSBURG
Magnitude: 57.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Radio reported public sighting of trees down on the east side of Five Island Lake.

Flash Flood in CALHOUN, IOWA
From 27-JUN-10 01:34:00 to 27-JUN-10 08:00:00 (CST-6)
Location: KNOKE
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flooding along Highway D15 near Garber and Janesville Avenues.

Flash Flood in CALHOUN, IOWA
From 27-JUN-10 01:34:00 to 27-JUN-10 08:00:00 (CST-6)
Location: POMEROY
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Underpass and viaduct flooding along Highway 4.

Flash Flood in WEBSTER, IOWA
From 27-JUN-10 02:34:00 to 27-JUN-10 07:00:00 (CST-6)
Location: (FOD)FT DODGE MUNI A
Flood cause: Heavy Rain
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Standing water across much of the city.  Water under Highway 169 underpass at railroad bridge.  Three feet of water at the Crossroads Mall.  Flooding along 1st Ave South and 2nd Ave North and at North 21st St.  Many other reports as well.

Heavy Rain in WEBSTER, IOWA
From 26-JUN-10 22:00:00 to 27-JUN-10 02:07:00 (CST-6)
Location: FT DODGE
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Trained Spotter

There was 3.5 inches of rainfall since 2200 CST.

Heavy Rain in CARROLL, IOWA
From 26-JUN-10 21:00:00 to 27-JUN-10 07:05:00 (CST-6)
Location: MANNING
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Overnight total of 2 inches.

Heavy Rain in HUMBOLDT, IOWA
From 26-JUN-10 21:00:00 to 27-JUN-10 08:49:00 (CST-6)
Location: RENWICK MUNI ARPT
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rainfall of 2.3 inches last night.

Thunderstorm Wind in MARION, IOWA
From 27-JUN-10 03:35:00 to 27-JUN-10 03:35:00 (CST-6)
Location: MELCHER
Magnitude: 61.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Grain bins destroyed, roof damage, and trees down on a farm.

Thunderstorm Wind in POLK, IOWA
From 27-JUN-10 03:22:00 to 27-JUN-10 03:22:00 (CST-6)
Location: ELKHART
Magnitude: 61.00 MG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in TAMA, IOWA
From 27-JUN-10 03:27:00 to 27-JUN-10 03:27:00 (CST-6)
Location: TAMA
Magnitude: 61.00 MG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Mesonet

Flash Flood in CRAWFORD, IOWA
From 27-JUN-10 05:00:00 to 27-JUN-10 08:00:00 (CST-6)
Location: WESTSIDE
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Heavy Rain in POLK, IOWA
From 27-JUN-10 03:30:00 to 27-JUN-10 05:00:00 (CST-6)
Location: URBANDALE
Property damage: 100.00K
Crop damage: 0.00K
Reported by: NWS Employee

Standing water 6 inches deep just south of Douglas and Merle Hay, couple inches of  flowing water at 63rd and Hickman, 1-2 feet of standing water at Washington and 68th.

Flash Flood in KOSSUTH, IOWA
From 26-JUN-10 20:00:00 to 26-JUN-10 22:00:00 (CST-6)
Location: ALGONA
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported flooding on Blackford and Overmeyer Roads with water flowing.

Thunderstorm Wind in EMMET, IOWA
From 26-JUN-10 20:19:00 to 26-JUN-10 20:19:00 (CST-6)
Location: ARMSTRONG
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported winds over Iowa Lake, north of Armstrong, estimated at 60 to 65 MPH.  Pea size hail also.

Thunderstorm Wind in EMMET, IOWA
From 26-JUN-10 20:08:00 to 26-JUN-10 20:08:00 (CST-6)
Location: WELLINGFORD
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous 3-5 inch tree branches down by high wind.

Thunderstorm Wind in WINNEBAGO, IOWA
From 26-JUN-10 21:13:00 to 26-JUN-10 21:13:00 (CST-6)
Location: SCARVILLE
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter reported power was out in town from straight line winds.

Thunderstorm Wind in EMMET, IOWA
From 26-JUN-10 20:04:00 to 26-JUN-10 20:04:00 (CST-6)
Location: DOLLIVER
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Winds estimated 60 to 65 MPH and wall cloud with rotation.

Thunderstorm Wind in WINNEBAGO, IOWA
From 26-JUN-10 20:45:00 to 26-JUN-10 20:45:00 (CST-6)
Location: THOMPSON
Magnitude: 65.00 EG
Property damage: 200.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported a farmstead with 4 grain bins destroyed.  Roof missing off shed and half of the structure destroyed.

Flash Flood in PALO ALTO, IOWA
From 26-JUN-10 21:15:00 to 26-JUN-10 22:30:00 (CST-6)
Location: RUTHVEN
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in WINNEBAGO, IOWA
From 26-JUN-10 20:49:00 to 26-JUN-10 20:49:00 (CST-6)
Location: BUFFALO CENTER
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported a fallen tree blocking Highway 9.