A strong push of moist and unstable air moved into Iowa during the day on the 24th.  Surface temperatures warmed into the low to mid 70s over much of western and southern Iowa with dew point temperatures in the low to mid 60s.  A cold front approached the state from the northwest during the evening.  The airmass was quite unstable with surface based lifted indices around -4 C. and most unstable CAPE around 2000 J/kg.  The shear was not real strong, but there was 30 to 40 kts of effective shear available.  CAPE in the -10 to -30 C. layer of the atmosphere was in the 200 to 300 J/kg range with 700 to 800 J/kg of DCAPE available.  The freezing level was relatively low, around 10,500 to 11,000 feet.  Thunderstorms erupted ahead of the approaching cold front.  Many of the storms produced hail with severe hail, with several reports of three quarter to one inch diameter hail reported from Audubon County northeast to Worth County, and east to Black Hawk County.  Golf ball size hail fell in Wright County south of the Dows area.  This was one of the larger reports.  A 60 MPH wind gust was reported as the storms moved through Hardin County.  One other report of high winds was received from Black Hawk County, where a pole shed was damaged.  The LCL was relatively low, in the 500 to 1000 meter range.  One tornado was reported north of Bancroft in Kossuth County early in the event.  A second tornado touched down in Hamilton County and caused tree damage and minor shed damage on 3 farms.  It was reported in an open area with little to no damage.  The shear values were strongest in that area as well.  The bulk of the severe weather moved out of the CWA just as a strong surface low pressure system begin to lift northeast along the advancing cold front.  A new round of severe weather moved into southwest Iowa and then into parts of central Iowa.  The severe weather from this second round was in the form of three quarter to one inch diameter hail.  Over the northeast part of the CWA, the main problem was with flooding and flash flooding. Rainfall over the northeast quarter of the CWA was in the 3 to 4 inch range, with spotty amounts as high as 5 inches in the Denver area.  Roads were washed out in numerous locations scattered from Tama County, north and northwest to Franklin County.  The areal flooding transitioned to significant river flooding, which will be addressed in a separate entry.

Flash Flood in BLACK HAWK, IOWA
From 25-APR-08 03:00:00 to 25-APR-08 09:45:00 (CST-6)
Location: CEDAR FALLS
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Sandbagging operations were being done around the fire station due to flooding from the Dry Run Creek.

Flash Flood in GRUNDY, IOWA
From 25-APR-08 05:00:00 to 25-APR-08 10:00:00 (CST-6)
Location: REINBECK
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Six inches of water was over the road due to flooding from Black Hawk Creek.

Flash Flood in FRANKLIN, IOWA
From 25-APR-08 07:00:00 to 25-APR-08 10:00:00 (CST-6)
Location: BEEDS LAKE ARPT
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: County Official

Flooding between Mallard and Nettles Roads at 180TH St. due to flooding around Otter Creek.

Flash Flood in BLACK HAWK, IOWA
From 25-APR-08 07:28:00 to 25-APR-08 09:45:00 (CST-6)
Location: CEDAR FALLS ISLEY AR
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Highway 57 Between Cedar Falls and Benson was under 2 feet of water.

Flash Flood in GRUNDY, IOWA
From 25-APR-08 08:50:00 to 25-APR-08 10:00:00 (CST-6)
Location: WELLSBURG
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: NWS Employee

The South Beaver Creek was flooding, affecting several gravel roads.

Flood in TAMA, IOWA
From 25-APR-08 09:00:00 to 25-APR-08 21:00:00 (CST-6)
Location: GLADBROOK
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Highway 96 east of Gladbrook was closed due to flooding.

Flood in HUMBOLDT, IOWA
From 25-APR-08 09:58:00 to 25-APR-08 22:00:00 (CST-6)
Location: PIONEER
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flood in BLACK HAWK, IOWA
From 25-APR-08 10:00:00 to 26-APR-08 09:45:00 (CST-6)
Location: CEDAR FALLS ISLEY AR
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flooding was reported along Black Hawk Creek and in Benson.

Flood in BLACK HAWK, IOWA
From 25-APR-08 16:38:00 to 26-APR-08 09:45:00 (CST-6)
Location: VOORHIES
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Broadcast Media

The Black Hawk County Sheriff reported the city of Hudson was inundated with water from Black Hawk Creek.  Sandbagging was underway, but failed to hold back the water.  A local emergency was declared.

Flood in BLACK HAWK, IOWA
From 25-APR-08 18:22:00 to 26-APR-08 09:45:00 (CST-6)
Location: DUNKERTON
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: County Official

Crane Creek was flooding portions of Dunkerton.  Evacuations were taking place along Main and Sycamore Street.

Flood in GRUNDY, IOWA
From 25-APR-08 10:00:00 to 26-APR-08 09:45:00 (CST-6)
Location: WELLSBURG
Flood cause: Heavy Rain
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Flood in HARDIN, IOWA
From 25-APR-08 10:00:00 to 26-APR-08 09:45:00 (CST-6)
Location: ACKLEY MUNI ARPT
Flood cause: Heavy Rain
Property damage: 150.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Flood in FRANKLIN, IOWA
From 25-APR-08 10:00:00 to 26-APR-08 09:45:00 (CST-6)
Location: SHEFFIELD
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Flood in WRIGHT, IOWA
From 25-APR-08 10:00:00 to 26-APR-08 09:45:00 (CST-6)
Location: FLORENCE
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Flood in BREMER, IOWA
From 25-APR-08 10:00:00 to 26-APR-08 09:45:00 (CST-6)
Location: PLAINFIELD
Flood cause: Heavy Rain
Property damage: 200.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Flash Flood in TAMA, IOWA
From 25-APR-08 00:30:00 to 25-APR-08 03:00:00 (CST-6)
Location: GLADBROOK
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Water reported over 170th St. in the Gladbrook area.

Flood in TAMA, IOWA
From 25-APR-08 09:00:00 to 25-APR-08 21:00:00 (CST-6)
Location: GLADBROOK
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

II Avenue was closed due to high water.

Flood in TAMA, IOWA
From 25-APR-08 09:00:00 to 25-APR-08 21:00:00 (CST-6)
Location: GLADBROOK
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

E Ave washed out along Wolf Creek.

Hail in WARREN, IOWA
From 25-APR-08 02:56:00 to 25-APR-08 02:56:00 (CST-6)
Location: SPRING HILL
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flood in BUTLER, IOWA
From 25-APR-08 10:00:00 to 26-APR-08 09:45:00 (CST-6)
Location: PARKERSBURG
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: County Official

Water was reported over the road in Parkersburg.

Flood in BLACK HAWK, IOWA
From 25-APR-08 14:30:00 to 26-APR-08 09:45:00 (CST-6)
Location: HUDSON
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: County Official

Additional roads were closed due to the flooding on the Black Hawk Creek.

Tornado in KOSSUTH, IOWA
From 24-APR-08 15:47:00 to 24-APR-08 15:47:00 (CST-6)
Location: GERLED
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Tornado was reported near the intersection of Highway 169 and 410th.  Tornado was reported by a Minnesota Deputy driving through Kossuth County and it was in an open area.

Tornado in HAMILTON, IOWA
From 24-APR-08 19:21:00 to 24-APR-08 19:24:00 (CST-6)
Location: STONEGA
Tornado F-scale: EF0
Property damage: 50.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A trained spotter sent a photo of a tornado and had driven back to the area where it was sighted.  Tree damage and minor damage was noted on three farmsteads with the tornado track toward the southeast.

Thunderstorm Wind in BLACK HAWK, IOWA
From 24-APR-08 22:10:00 to 24-APR-08 22:10:00 (CST-6)
Location: WATERLOO
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Damage was done to a pole shed.

Thunderstorm Wind in HARDIN, IOWA
From 24-APR-08 20:00:00 to 24-APR-08 20:00:00 (CST-6)
Location: IOWA FALLS
Magnitude: 52.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in HAMILTON, IOWA
From 24-APR-08 19:35:00 to 24-APR-08 19:35:00 (CST-6)
Location: BLAIRSBURG
Magnitude: 61.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A power poll was snapped at 210th St and Quinn Ave.

Thunderstorm Wind in HAMILTON, IOWA
From 24-APR-08 19:50:00 to 24-APR-08 19:50:00 (CST-6)
Location: BLAIRSBURG
Magnitude: 57.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Metal Debris on the road near 200th St and Highway 69 intersection.

Hail in UNION, IOWA
From 25-APR-08 02:20:00 to 25-APR-08 02:20:00 (CST-6)
Location: LORIMOR
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Flash Flood in BREMER, IOWA
From 24-APR-08 21:30:00 to 25-APR-08 10:00:00 (CST-6)
Location: WAVERLY
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roads were washed out in various parts of the county.

Flash Flood in BREMER, IOWA
From 25-APR-08 05:00:00 to 25-APR-08 05:00:00 (CST-6)
Location: DENVER
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Part of the town was being evacuated due to flooding.

Flash Flood in BUTLER, IOWA
From 25-APR-08 06:00:00 to 25-APR-08 10:00:00 (CST-6)
Location: BUTLER CENTER
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: County Official

Water was reported over the road along County Road C45, 2 miles east of Highway 14.

Flash Flood in HARDIN, IOWA
From 25-APR-08 04:00:00 to 25-APR-08 10:00:00 (CST-6)
Location: BUCKEYE
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Broadcast Media

KCCI viewers reported the South Fork of the Iowa River was out of its banks.  Viewer said it was the highest level they have ever seen.

Hail in WARREN, IOWA
From 25-APR-08 02:56:00 to 25-APR-08 02:56:00 (CST-6)
Location: SPRING HILL
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in POLK, IOWA
From 25-APR-08 03:11:00 to 25-APR-08 03:11:00 (CST-6)
Location: AVON
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Public report received through e-spotter.

Hail in RINGGOLD, IOWA
From 25-APR-08 02:29:00 to 25-APR-08 02:29:00 (CST-6)
Location: ELLSTON
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in WARREN, IOWA
From 25-APR-08 02:50:00 to 25-APR-08 02:50:00 (CST-6)
Location: NEW VIRGINIA
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in WARREN, IOWA
From 25-APR-08 03:17:00 to 25-APR-08 03:17:00 (CST-6)
Location: LIBERTY CENTER
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in AUDUBON, IOWA
From 24-APR-08 18:17:00 to 24-APR-08 18:17:00 (CST-6)
Location: ROSS
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail was near the intersection of 150th and Falcon.

Hail in WORTH, IOWA
From 24-APR-08 19:19:00 to 24-APR-08 19:19:00 (CST-6)
Location: MANLY
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in GREENE, IOWA
From 24-APR-08 19:25:00 to 24-APR-08 19:25:00 (CST-6)
Location: JEFFERSON
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Nickel size hail was reported in Jefferson.

Hail in WRIGHT, IOWA
From 24-APR-08 19:44:00 to 24-APR-08 19:44:00 (CST-6)
Location: DOWS
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in BUTLER, IOWA
From 24-APR-08 21:03:00 to 24-APR-08 21:03:00 (CST-6)
Location: CLARKSVILLE
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in WARREN, IOWA
From 25-APR-08 03:09:00 to 25-APR-08 03:09:00 (CST-6)
Location: LIBERTY CENTER
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail the size of quarters reported on Tyler street, 6 miles west and 1 mile north of Lacona.

Hail in KOSSUTH, IOWA
From 24-APR-08 17:24:00 to 24-APR-08 17:24:00 (CST-6)
Location: LU VERNE
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in AUDUBON, IOWA
From 24-APR-08 18:01:00 to 24-APR-08 18:01:00 (CST-6)
Location: FISCUS
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Flash Flood in HARDIN, IOWA
From 25-APR-08 08:30:00 to 25-APR-08 10:00:00 (CST-6)
Location: IOWA FALLS MUNI ARPT
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: NWS Employee

A small tributary was reported to be out of its banks at the intersection of Highway 20.  No impacts were noted.