A cold front dropped southeast into Iowa during the late afternoon and evening of the 3rd.  The atmosphere became quite unstable with temperatures rising into the low to mid 80s and dewpoints in the 55 to 60 degree range.  As thunderstorms began to form along the front, CAPE had risen to around 2000 J/kg with CAPE in the -10 to -30 C layer of the atmosphere between 300 and 500 J/kg. The freezing level was between 11,500 and 12,000 feet.  Downdraft CAPE was in the 1000 to 1200 J/kg range.  Though many parameters were favorable, the shear was limited with 25 to 30 kts of effective shear available.  Thunderstorms formed along the cold front and became severe relatively quickly.  The main severe weather with the storms was hail with most of the hail reported around quarter size.  Hail covered the ground in a few areas.  Nearly baseball size hail fell in Calhoun County at Manson.  The storm in Algona produced a 59 MPH wind gust at the airport.

Hail in KOSSUTH, IOWA
From 03-MAY-15 16:45:00 to 03-MAY-15 16:45:00 (CST-6)
Location: SENECA
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported that quarter size hail nearly covered the gruond.

Hail in PALO ALTO, IOWA
From 03-MAY-15 18:00:00 to 03-MAY-15 18:00:00 (CST-6)
Location: WEST BEND
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Public

Hail in WORTH, IOWA
From 03-MAY-15 18:20:00 to 03-MAY-15 18:20:00 (CST-6)
Location: SILVER LAKE
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WEBSTER, IOWA
From 03-MAY-15 19:08:00 to 03-MAY-15 19:08:00 (CST-6)
Location: BADGER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Pea to nickel size hail was reported.

Hail in WEBSTER, IOWA
From 03-MAY-15 19:15:00 to 03-MAY-15 19:15:00 (CST-6)
Location: (FOD)FT DODGE MUNI A
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in KOSSUTH, IOWA
From 03-MAY-15 17:45:00 to 03-MAY-15 17:45:00 (CST-6)
Location: ALGONA MUNI ARPT
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Hail in CALHOUN, IOWA
From 03-MAY-15 21:51:00 to 03-MAY-15 21:51:00 (CST-6)
Location: MANSON
Magnitude: 2.50 
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in GRUNDY, IOWA
From 04-MAY-15 00:00:00 to 04-MAY-15 00:00:00 (CST-6)
Location: WELLSBURG
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CALHOUN, IOWA
From 03-MAY-15 21:52:00 to 03-MAY-15 21:52:00 (CST-6)
Location: MANSON
Magnitude: 2.50 
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Significant damage was done to a vehicle from the large hail.

Thunderstorm Wind in EMMET, IOWA
From 03-MAY-15 16:45:00 to 03-MAY-15 16:45:00 (CST-6)
Location: RALEIGH
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

Minor tree damage reported with the wind.

Hail in EMMET, IOWA
From 03-MAY-15 16:45:00 to 03-MAY-15 16:45:00 (CST-6)
Location: RALEIGH
Magnitude: 1.50 
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Public

Sixty MPH wind gusts occurred with the hail.

Hail in CALHOUN, IOWA
From 03-MAY-15 21:35:00 to 03-MAY-15 21:45:00 (CST-6)
Location: MANSON
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A shower of quarter size hail occurred with a window broken out.