A weak cold front moved through the state during the afternoon of the 4th.  This front stalled south of Iowa and became a warm front during the day on the 5th.  The boundary set the stage for strong lift and thunderstorm development already by the morning of the 5th, and continued through the day.  The atmosphere became quite unstable with most unstable CAPE values rising to the 1000-2500 J/kg range by early afternoon.  There was considerable deep shear with 60 to 70 kts available in the 0-6 km layer.  The LCL level fell as the front lifted north, falling to 750 meters along the frontal boundary.  The initial severe weather that occurred was in the form of large hail.  The available CAPE in the -10 to -30 C layer of the atmosphere was around 200 J/kg in a relatively low freezing level environment.  The freezing level was in the 10,000 to 12,000 foot range.  Considerable moisture streamed north to feed the storms.  In spite of the surface dews points north of the front in the upper 30s and 40s, readings in the 60s were found just south of the boundary.  Precipitable water values rose to 1.25 inches over southern Iowa by early afternoon.  Many of the storms produced hail, with numerous reports in the one inch to golf ball size category.  The largest hail occurred over south central Iowa with golf ball size hail reported in Clarke County.  A secondary round of storms moved through south central into central Iowa by mid afternoon.  One of the storms dropped golf ball size hail in Marion County as well, completely covering the ground.  The same cluster of storms continued northeast with large hail reported.  Half dollar size hail covered the ground in Poweshiek County near Deep River.  Another round of thunderstorms developed over northeast Iowa during the afternoon, but they only produced some small hail.  Thunderstorm activity decreased during the early evening hours, but began to fire again after sunset as the low level jet developed.  Surface winds of 25 to 40 kts from the south developed over Kansas during the evening, with 850 mb winds increasing to southwest at 50 to 60 kts.  Most Unstable CAPE increased to 2000 to 3000 J/kg, while the CAPE in the -10 to -30 C layer of the atmosphere increased to between 200 and 400 J/kg.  Freezing levels increased slightly to a relatively uniform 12,000 feet.  Strong thunderstorms formed over southeast Nebraska into southwest Iowa before midnight and continued to track northeast.  The storms produced hail, though not as large as the hail during the afternoon for the most part.  One of the stronger storms produced golf ball size hail briefly as it moved northeast of Perry.  During the predawn hours, downdraft CAPE increased to 700 to 800 J/kg.  A cluster of thunderstorms moving across Iowa formed a small mesoscale low and produced a bow echo segment.  Gusty winds resulted, however most were below 50 MPH.  As the storm moved through Polk County, a 63 MPH wind gust was reported by an RWIS site in Altoona.

Hail in WARREN, IOWA
From 05-APR-10 12:04:00 to 05-APR-10 12:04:00 (CST-6)
Location: INDIANOLA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in DALLAS, IOWA
From 05-APR-10 12:13:00 to 05-APR-10 12:13:00 (CST-6)
Location: DE SOTO
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in POLK, IOWA
From 05-APR-10 12:15:00 to 05-APR-10 12:15:00 (CST-6)
Location: JOHNSTON
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in POLK, IOWA
From 05-APR-10 12:21:00 to 05-APR-10 12:21:00 (CST-6)
Location: CLOVER HILLS
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in RINGGOLD, IOWA
From 05-APR-10 12:21:00 to 05-APR-10 12:21:00 (CST-6)
Location: KNOWLTON
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in RINGGOLD, IOWA
From 05-APR-10 12:35:00 to 05-APR-10 12:35:00 (CST-6)
Location: DELPHOS
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in RINGGOLD, IOWA
From 05-APR-10 13:08:00 to 05-APR-10 13:08:00 (CST-6)
Location: KNOWLTON
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in RINGGOLD, IOWA
From 05-APR-10 13:28:00 to 05-APR-10 13:28:00 (CST-6)
Location: ELLSTON
Magnitude: 1.50 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CLARKE, IOWA
From 05-APR-10 13:44:00 to 05-APR-10 13:44:00 (CST-6)
Location: HOPEVILLE
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WARREN, IOWA
From 05-APR-10 14:30:00 to 05-APR-10 14:30:00 (CST-6)
Location: LACONA
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Hail in MARION, IOWA
From 05-APR-10 11:37:00 to 05-APR-10 11:37:00 (CST-6)
Location: DONNELLY
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in POWESHIEK, IOWA
From 06-APR-10 02:30:00 to 06-APR-10 02:30:00 (CST-6)
Location: BROOKLYN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in POLK, IOWA
From 06-APR-10 02:31:00 to 06-APR-10 02:31:00 (CST-6)
Location: ALTOONA
Magnitude: 61.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Mesonet

Hail in MARION, IOWA
From 05-APR-10 11:39:00 to 05-APR-10 11:39:00 (CST-6)
Location: KNOXVILLE
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MARION, IOWA
From 05-APR-10 14:42:00 to 05-APR-10 14:42:00 (CST-6)
Location: NEPAS
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Hail in MARION, IOWA
From 05-APR-10 14:50:00 to 05-APR-10 14:50:00 (CST-6)
Location: KNOXVILLE ARPT
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in MARION, IOWA
From 05-APR-10 14:52:00 to 05-APR-10 14:52:00 (CST-6)
Location: KNOXVILLE
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in MARION, IOWA
From 05-APR-10 15:04:00 to 05-APR-10 15:04:00 (CST-6)
Location: PELLA
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MARION, IOWA
From 05-APR-10 15:10:00 to 05-APR-10 15:10:00 (CST-6)
Location: PELLA
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CLARKE, IOWA
From 05-APR-10 13:45:00 to 05-APR-10 13:45:00 (CST-6)
Location: MURRAY
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in AUDUBON, IOWA
From 05-APR-10 23:21:00 to 05-APR-10 23:21:00 (CST-6)
Location: EXIRA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in GUTHRIE, IOWA
From 06-APR-10 00:08:00 to 06-APR-10 00:08:00 (CST-6)
Location: FANSLERS
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in DALLAS, IOWA
From 06-APR-10 00:30:00 to 06-APR-10 00:30:00 (CST-6)
Location: PERRY
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in DALLAS, IOWA
From 06-APR-10 00:33:00 to 06-APR-10 00:33:00 (CST-6)
Location: PERRY
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in DALLAS, IOWA
From 05-APR-10 12:15:00 to 05-APR-10 12:15:00 (CST-6)
Location: VAN METER
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail was reported at the Van Meter fire station.

Hail in POLK, IOWA
From 05-APR-10 12:31:00 to 05-APR-10 12:31:00 (CST-6)
Location: DODGE FLD ARPT
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Nickel to quarter size hail was covering the ground.

Hail in CLARKE, IOWA
From 05-APR-10 13:36:00 to 05-APR-10 13:36:00 (CST-6)
Location: HOPEVILLE
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail reported by the Sheriff's deputy in the small town of Hopeville.

Hail in MARION, IOWA
From 05-APR-10 14:37:00 to 05-APR-10 14:37:00 (CST-6)
Location: NEWBERN
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

The ground was white with hail.

Hail in MARION, IOWA
From 05-APR-10 14:55:00 to 05-APR-10 14:55:00 (CST-6)
Location: KNOXVILLE
Magnitude: 1.50 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Hail in MARION, IOWA
From 05-APR-10 14:54:00 to 05-APR-10 14:54:00 (CST-6)
Location: KNOXVILLE
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MARION, IOWA
From 05-APR-10 14:55:00 to 05-APR-10 14:55:00 (CST-6)
Location: KNOXVILLE
Magnitude: 1.25 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MARION, IOWA
From 05-APR-10 15:11:00 to 05-APR-10 15:11:00 (CST-6)
Location: PELLA
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MARION, IOWA
From 05-APR-10 15:12:00 to 05-APR-10 15:12:00 (CST-6)
Location: PELLA
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in POWESHIEK, IOWA
From 05-APR-10 15:46:00 to 05-APR-10 15:46:00 (CST-6)
Location: DEEP RIVER
Magnitude: 1.25 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

The hail covered the ground.

Hail in POWESHIEK, IOWA
From 05-APR-10 15:48:00 to 05-APR-10 15:48:00 (CST-6)
Location: DEEP RIVER
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in MARION, IOWA
From 05-APR-10 14:40:00 to 05-APR-10 14:40:00 (CST-6)
Location: MELCHER
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in MARION, IOWA
From 05-APR-10 14:51:00 to 05-APR-10 14:51:00 (CST-6)
Location: FLAGLER
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in AUDUBON, IOWA
From 05-APR-10 23:15:00 to 05-APR-10 23:15:00 (CST-6)
Location: GRAY
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in GREENE, IOWA
From 05-APR-10 23:43:00 to 05-APR-10 23:43:00 (CST-6)
Location: SCRANTON
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter