A warm front was positioned from northeast Nebraska, southeast across central into east central Iowa.  Thunderstorms fired north of the front during the night, and the activity continued into the day.  A 25 kt low level jet continued to feed moisture into the atmosphere during the day.  By early to mid afternoon, most unstable CAPE reached 1900 J/kg, with lifted indices around -7 C.  Though there was considerable downdraft CAPE available at around 1400 J/kg, it was not realized.  The atmosphere was weakly sheared with about 30 kts of shear present.  Hail was the main feature with the storms.  The freezing level was low, sloping from around 9600 feet over central Minnesota, to 10,800 feet at Omaha.  Numerous reports of hail ranging from nickel to golf ball size were received.  Golf ball size hail fell in Kossuth and Pocahontas Counties.  Many locations reported that the hail covered the ground.  The storms also produced very heavy rainfall.  With over an inch of precipitable water available, the storms were quite efficient.  Two to two and one half inches of rainfall was reported from near Spencer to Thompson.  Though flash flooding did not occur, the heavy rain pushed rivers over flood stage.

Hail in PALO ALTO, IOWA
From 12-APR-10 14:15:00 to 12-APR-10 14:15:00 (CST-6)
Location: EMMETSBURG
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Largest hail was on the south side of town where golf ball size hail was reported.  Quarter size hail fell on the north side of town.

Hail in KOSSUTH, IOWA
From 12-APR-10 15:47:00 to 12-APR-10 15:47:00 (CST-6)
Location: ALGONA
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter arrived home from work at 1611 CST with quarter size hail still on the ground.  The start time was estimated.

Hail in PALO ALTO, IOWA
From 12-APR-10 14:10:00 to 12-APR-10 14:10:00 (CST-6)
Location: EMMETSBURG
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail beginning to accumulate at the time of observation.

Hail in HANCOCK, IOWA
From 12-APR-10 15:35:00 to 12-APR-10 15:35:00 (CST-6)
Location: CORWITH
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in KOSSUTH, IOWA
From 12-APR-10 15:38:00 to 12-APR-10 15:38:00 (CST-6)
Location: ALGONA
Magnitude: 1.50 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in PALO ALTO, IOWA
From 12-APR-10 14:07:00 to 12-APR-10 14:07:00 (CST-6)
Location: EMMETSBURG ARPT
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in PALO ALTO, IOWA
From 12-APR-10 14:13:00 to 12-APR-10 14:13:00 (CST-6)
Location: EMMETSBURG ARPT
Magnitude: 1.25 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in KOSSUTH, IOWA
From 12-APR-10 15:39:00 to 12-APR-10 15:39:00 (CST-6)
Location: ALGONA
Magnitude: 1.75 
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in KOSSUTH, IOWA
From 12-APR-10 15:41:00 to 12-APR-10 15:41:00 (CST-6)
Location: ALGONA
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

Hail in KOSSUTH, IOWA
From 12-APR-10 15:37:00 to 12-APR-10 15:37:00 (CST-6)
Location: ALGONA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in HANCOCK, IOWA
From 12-APR-10 17:00:00 to 12-APR-10 17:00:00 (CST-6)
Location: DENHART
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in PALO ALTO, IOWA
From 12-APR-10 14:09:00 to 12-APR-10 14:09:00 (CST-6)
Location: EMMETSBURG
Magnitude: 1.25 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: COOP Observer