The upper level low pressure that affected the state the previous day continued to move closer to the state.  A complicated setup took place as it approached.  Initially, a pseudo warm front lifted north across the state.  A strong push of moisture sent dewpoint temperatures into the mid 60s to around 70.  Meanwhile, a cold front/dryline pushed into western Iowa during the day with dewpoints in its wake in the low to mid 50s.  The atmosphere became unstable as the day progressed.  With the cold core low moving toward Iowa, the freezing level was quite low, around 10,500 feet.  CAPE in the -10 to -30 layer of the atmosphere was between 600 and 800 J/kg.  The downdraft CAPE was between 800 and 1100 J/kg.  By mid afternoon, CAPE increased to 2500 to 4000 J/kg and lifted indices fell to -10 to -13 C.  Shear increased across the state with 50 to 55 kts of shear available at the time of initiation.  The LCL was relatively low, in the 750 to 1000 meters.  The 0-1 km SRH values were around 150.  There was more moisture available than was in place the previous day with PWAT values in the 1 to 1.25 inch range.  Thunderstorms formed in two areas.  The first was along the dryline over southeast Iowa.  The storms became severe quickly and produced severe hail.  The largest was golf ball size with the storms as they moved through Mahaska and Poweshiek Counties.  Over northern Iowa, a line of thunderstorms formed on the edge of the cold pool as it interacted with the deepening moisture.  These storms produced hail and several funnel clouds.  Hail from this line was around an inch or less in diameter.  One tornado touched down briefly southeast of Tripoli.

Hail in BREMER, IOWA
From 22-MAY-11 14:26:00 to 22-MAY-11 14:26:00 (CST-6)
Location: SUMNER
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in BREMER, IOWA
From 22-MAY-11 13:50:00 to 22-MAY-11 13:50:00 (CST-6)
Location: TRIPOLI
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Hail in BREMER, IOWA
From 22-MAY-11 14:15:00 to 22-MAY-11 14:15:00 (CST-6)
Location: TRIPOLI
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 3.00K
Reported by: Emergency Manager

Hail in DAVIS, IOWA
From 22-MAY-11 15:20:00 to 22-MAY-11 15:20:00 (CST-6)
Location: WEST GROVE
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in POWESHIEK, IOWA
From 22-MAY-11 13:10:00 to 22-MAY-11 13:10:00 (CST-6)
Location: BROOKLYN
Magnitude: 1.50 
Property damage: 5.00K
Crop damage: 3.00K
Reported by: COOP Observer

Hail in BREMER, IOWA
From 22-MAY-11 14:25:00 to 22-MAY-11 14:25:00 (CST-6)
Location: SUMNER
Magnitude: 2.00 
Property damage: 10.00K
Crop damage: 3.00K
Reported by: Utility Company

Tornado in BREMER, IOWA
From 22-MAY-11 14:13:00 to 22-MAY-11 14:13:00 (CST-6)
Location: TRIPOLI
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Funnel cloud reached three quarters of the way to the ground.

Hail in POWESHIEK, IOWA
From 22-MAY-11 13:15:00 to 22-MAY-11 13:15:00 (CST-6)
Location: BROOKLYN
Magnitude: 1.50 
Property damage: 5.00K
Crop damage: 3.00K
Reported by: Trained Spotter

Funnel Cloud in BREMER, IOWA
From 22-MAY-11 13:50:00 to 22-MAY-11 13:50:00 (CST-6)
Location: BABCOCK
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in POWESHIEK, IOWA
From 22-MAY-11 13:10:00 to 22-MAY-11 13:10:00 (CST-6)
Location: BROOKLYN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 3.00K
Reported by: Trained Spotter

Hail in MAHASKA, IOWA
From 22-MAY-11 13:09:00 to 22-MAY-11 13:09:00 (CST-6)
Location: BARNES CITY
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Quarter size hail nearly covering the ground.

Hail in BLACK HAWK, IOWA
From 22-MAY-11 13:38:00 to 22-MAY-11 13:38:00 (CST-6)
Location: FARMER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Oblong hail stones were nickel sized.

Hail in MAHASKA, IOWA
From 22-MAY-11 13:10:00 to 22-MAY-11 13:10:00 (CST-6)
Location: BARNES CITY
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 3.00K
Reported by: Trained Spotter

Trained spotter reported golf ball hail.

Hail in POWESHIEK, IOWA
From 22-MAY-11 13:15:00 to 22-MAY-11 13:15:00 (CST-6)
Location: CARNFORTH
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Funnel Cloud in BLACK HAWK, IOWA
From 22-MAY-11 13:47:00 to 22-MAY-11 13:47:00 (CST-6)
Location: FARMER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported a funnel cloud northwest of Cedar Falls.

Hail in BLACK HAWK, IOWA
From 22-MAY-11 13:40:00 to 22-MAY-11 13:40:00 (CST-6)
Location: NORTH CEDAR
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in POWESHIEK, IOWA
From 22-MAY-11 13:10:00 to 22-MAY-11 13:10:00 (CST-6)
Location: MALCOLM
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 6.00K
Reported by: Trained Spotter

Hail in WAPELLO, IOWA
From 22-MAY-11 15:12:00 to 22-MAY-11 15:12:00 (CST-6)
Location: ELDON
Magnitude: 1.50 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Quarter to ping pong ball size hail.