A strong push of moisture streamed into Iowa on a 50 to 70 kt low level jet.  Lifted indices were around -9 C at the beginning of the event with CAPE in the 2500 to 4000 J/kg range.  Thunderstorms erupted to the west and southwest of Iowa with the initial development being discrete supercells to the southwest, and linear ahead of an approaching cold front to the west.  The storms became much more multi-cellular as they moved into Iowa.  As a result, competition for moisture caused the storms to weaken.  The storms that were severe in Iowa produced high winds in what appears to be several microburst events.  Winds of 74 MPH were recorded at the Ames Airport, with 73 MPH winds measured at a mesonet site in Adair.  A few other reports of severe winds were received with tree damage south of Adair and also in the Earlham area.  There were only a few reports of hail from the storms.  Hail that did occur was limited to an inch or less in diameter.

Hail in DECATUR, IOWA
From 29-MAY-04 23:40:00 to 29-MAY-04 23:40:00 (CST)
Location: PLEASANTON
Magnitude: 1.00 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in HAMILTON, IOWA
From 29-MAY-04 23:50:00 to 29-MAY-04 23:50:00 (CST)
Location: RANDALL
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in HARDIN, IOWA
From 29-MAY-04 23:55:00 to 29-MAY-04 23:55:00 (CST)
Location: RADCLIFFE
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in ADAIR, IOWA
From 30-MAY-04 01:07:00 to 30-MAY-04 01:07:00 (CST)
Location: ADAIR
Magnitude: 52 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in MADISON, IOWA
From 30-MAY-04 01:38:00 to 30-MAY-04 01:38:00 (CST)
Location: EARLHAM
Magnitude: 52 EG
Property damage: 2K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in STORY, IOWA
From 29-MAY-04 23:45:00 to 29-MAY-04 23:45:00 (CST)
Location: ROLAND
Magnitude: 52 EG
Property damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in DECATUR, IOWA
From 29-MAY-04 23:20:00 to 29-MAY-04 23:20:00 (CST)
Location: DAVIS CITY
Magnitude: 52 EG
Property damage: 2K
Reported by: OFFICIAL NWS OBS.

Thunderstorm Wind in RINGGOLD, IOWA
From 29-MAY-04 22:35:00 to 29-MAY-04 22:35:00 (CST)
Location: MT AYR
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in ADAIR, IOWA
From 30-MAY-04 01:01:00 to 30-MAY-04 01:01:00 (CST)
Location: ADAIR
Magnitude: 63 MG
Property damage: 5K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in WAYNE, IOWA
From 30-MAY-04 00:00:00 to 30-MAY-04 00:00:00 (CST)
Location: ALLERTON
Magnitude: 52 EG
Property damage: 2K
Reported by: OFFICIAL NWS OBS.

Hail in APPANOOSE, IOWA
From 30-MAY-04 01:15:00 to 30-MAY-04 01:15:00 (CST)
Location: CENTERVILLE
Magnitude: 0.88 
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in GUTHRIE, IOWA
From 30-MAY-04 01:25:00 to 30-MAY-04 01:25:00 (CST)
Location: JAMAICA
Magnitude: 57 EG
Property damage: 5K
Reported by: NWS EMPLOYEE(OFF DUTY)

Thunderstorm Wind in STORY, IOWA
From 29-MAY-04 23:27:00 to 29-MAY-04 23:27:00 (CST)
Location: AMES ARPT
Magnitude: 64 MG
Property damage: 2K
Reported by: AWOS,ASOS,MESONET,ETC