A very warm and unstable airmass was in place over Iowa.  The moisture was in limited supply with this event.  A cold front approached the state from the northwest.  This front moved into the state during the late afternoon and evening of the 16th.  Moisture was limited with this system.  Surface dew points were in the mid 50s to around 60 during the early part of the afternoon over the southeast half of the state.  The moisture was very shallow.  Afternoon mixing lowered dew points into the upper 40s over the southeast, and into the upper 20s and 30s over the northwest just ahead of the front.  Temperatures warmed into mid 80s to low 90s which made the airmass quite unstable.  CAPE values were around 1000 J/kg with Lifted Indices around -4 C. just ahead of the front.  Convection had a hard time getting organized at first with only spotty cells forming ahead of the front.  By early evening, a small MCS formed over western Iowa and advanced east-southeast across the state.  The MCS produced hail in many locations along with gusty winds.  In spite of the "inverted V" type upper air soundings, high winds were not as widespread as would normally be expected.  Several locations did report gusts to around 60 MPH.  High winds blew a car off of Interstate 80 in Poweshiek County southeast of Malcom.  A wind gust of 70 MPH was reported at the Ames Airport in Story County.  For the most part, the hail was in the three quarter to one inch diameter size.  Hail did cover the ground in Carroll County at Lidderdale.  The largest hail report came from Guthrie County north of Panora into the Panora area.  Golf ball size hail was reported at that location.  There were several reports of gutter damage and dents in car hoods due to the hail in Panora.  Overall, damage was limited with this event since tree leaves were only beginning to come out and the crops had not yet been planted.

Hail in STORY, IOWA
From 16-APR-04 20:32:00 to 16-APR-04 20:32:00 (CST)
Location: AMES
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Hail in POLK, IOWA
From 16-APR-04 23:10:00 to 16-APR-04 23:10:00 (CST)
Location: BONDURANT
Magnitude: 1.00 
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in STORY, IOWA
From 16-APR-04 20:34:00 to 16-APR-04 20:34:00 (CST)
Location: AMES
Magnitude: 60 EG
Reported by: NWS EMPLOYEE(OFF DUTY)

Thunderstorm Wind in GUTHRIE, IOWA
From 16-APR-04 20:42:00 to 16-APR-04 20:42:00 (CST)
Location: GUTHRIE CENTER
Magnitude: 61 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in FRANKLIN, IOWA
From 16-APR-04 20:36:00 to 16-APR-04 20:36:00 (CST)
Location: HAMPTON
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 16-APR-04 20:22:00 to 16-APR-04 20:22:00 (CST)
Location: BOONE
Magnitude: 50 MG
Reported by: AWOS,ASOS,MESONET,ETC

Hail in POLK, IOWA
From 16-APR-04 21:15:00 to 16-APR-04 21:15:00 (CST)
Location: ALTOONA
Magnitude: 0.88 
Reported by: TRAINED SPOTTER

Hail in POLK, IOWA
From 16-APR-04 21:21:00 to 16-APR-04 21:21:00 (CST)
Location: ALTOONA
Magnitude: 1.00 
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in DALLAS, IOWA
From 16-APR-04 22:13:00 to 16-APR-04 22:13:00 (CST)
Location: DALLAS CENTER
Magnitude: 0.88 
Reported by: AMATEUR RADIO

Thunderstorm Wind in POWESHIEK, IOWA
From 16-APR-04 22:06:00 to 16-APR-04 22:06:00 (CST)
Location: MALCOLM
Magnitude: 50 EG
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in POWESHIEK, IOWA
From 16-APR-04 22:08:00 to 16-APR-04 22:08:00 (CST)
Location: BROOKLYN
Magnitude: 50 MG
Reported by: AWOS,ASOS,MESONET,ETC

Hail in GUTHRIE, IOWA
From 16-APR-04 21:22:00 to 16-APR-04 21:22:00 (CST)
Location: PANORA
Magnitude: 1.00 
Property damage: 5K
Reported by: BROADCAST MEDIA

Hail in GREENE, IOWA
From 16-APR-04 19:30:00 to 16-APR-04 19:30:00 (CST)
Location: CHURDAN
Magnitude: 1.25 
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in POLK, IOWA
From 16-APR-04 22:35:00 to 16-APR-04 22:35:00 (CST)
Location: GRIMES
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Hail in HARDIN, IOWA
From 16-APR-04 21:25:00 to 16-APR-04 21:25:00 (CST)
Location: STEAMBOAT ROCK
Magnitude: 0.88 
Reported by: TRAINED SPOTTER

Thunderstorm Wind in STORY, IOWA
From 16-APR-04 20:32:00 to 16-APR-04 20:32:00 (CST)
Location: AMES
Magnitude: 52 EG
Reported by: NWS EMPLOYEE(OFF DUTY)

Hail in GUTHRIE, IOWA
From 16-APR-04 20:59:00 to 16-APR-04 20:59:00 (CST)
Location: GUTHRIE CENTER
Magnitude: 1.00 
Property damage: 3K
Reported by: TRAINED SPOTTER

Hail in CARROLL, IOWA
From 16-APR-04 18:35:00 to 16-APR-04 18:35:00 (CST)
Location: LIDDERDALE
Magnitude: 0.88 
Property damage: 2K
Reported by: FIRE DEPT/RESCUE SQUAD

Hail in POLK, IOWA
From 16-APR-04 22:41:00 to 16-APR-04 22:41:00 (CST)
Location: JOHNSTON
Magnitude: 1.00 
Property damage: 5K
Reported by: NWS EMPLOYEE(OFF DUTY)

Hail in POLK, IOWA
From 16-APR-04 21:10:00 to 16-APR-04 21:10:00 (CST)
Location: BONDURANT
Magnitude: 0.88 
Reported by: OFFICIAL NWS OBS.

Hail in HAMILTON, IOWA
From 16-APR-04 20:05:00 to 16-APR-04 20:05:00 (CST)
Location: STRATFORD
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Thunderstorm Wind in STORY, IOWA
From 16-APR-04 20:31:00 to 16-APR-04 20:31:00 (CST)
Location: AMES ARPT
Magnitude: 61 MG
Property damage: 2K
Reported by: AWOS,ASOS,MESONET,ETC

Hail in GUTHRIE, IOWA
From 16-APR-04 21:26:00 to 16-APR-04 21:26:00 (CST)
Location: PANORA
Magnitude: 1.75 
Property damage: 10K
Reported by: BROADCAST MEDIA

Hail in DALLAS, IOWA
From 16-APR-04 21:49:00 to 16-APR-04 21:49:00 (CST)
Location: MINBURN
Magnitude: 1.00 
Property damage: 1K
Reported by: STORM CHASER

Hail in GUTHRIE, IOWA
From 16-APR-04 21:00:00 to 16-APR-04 21:00:00 (CST)
Location: PANORA
Magnitude: 1.75 
Property damage: 20K
Reported by: GENERAL PUBLIC

Thunderstorm Wind in STORY, IOWA
From 16-APR-04 20:29:00 to 16-APR-04 20:29:00 (CST)
Location: AMES
Magnitude: 52 EG
Reported by: TRAINED SPOTTER

Hail in BOONE, IOWA
From 16-APR-04 20:30:00 to 16-APR-04 20:30:00 (CST)
Location: BOONE
Magnitude: 1.00 
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in STORY, IOWA
From 16-APR-04 20:50:00 to 16-APR-04 20:50:00 (CST)
Location: KELLEY
Magnitude: 50 EG
Reported by: EMERGENCY MANAGER

Hail in CARROLL, IOWA
From 16-APR-04 18:34:00 to 16-APR-04 18:34:00 (CST)
Location: LIDDERDALE
Magnitude: 0.88 
Property damage: 2K
Reported by: LAW ENFORCEMENT

Hail in JASPER, IOWA
From 16-APR-04 21:38:00 to 16-APR-04 21:38:00 (CST)
Location: NEWTON
Magnitude: 1.00 
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in DALLAS, IOWA
From 16-APR-04 21:54:00 to 16-APR-04 21:54:00 (CST)
Location: DALLAS CENTER
Magnitude: 0.88 
Reported by: TRAINED SPOTTER

Thunderstorm Wind in STORY, IOWA
From 16-APR-04 20:25:00 to 16-APR-04 20:25:00 (CST)
Location: AMES
Magnitude: 52 EG
Reported by: LAW ENFORCEMENT

Hail in BUTLER, IOWA
From 16-APR-04 20:36:00 to 16-APR-04 20:36:00 (CST)
Location: AREDALE
Magnitude: 0.88 
Reported by: TRAINED SPOTTER

Hail in DALLAS, IOWA
From 16-APR-04 22:20:00 to 16-APR-04 22:20:00 (CST)
Location: DALLAS CENTER
Magnitude: 1.50 
Property damage: 10K
Reported by: STORM CHASER

Hail in POLK, IOWA
From 16-APR-04 22:51:00 to 16-APR-04 22:51:00 (CST)
Location: POLK CITY
Magnitude: 0.88 
Reported by: AMATEUR RADIO

Hail in GUTHRIE, IOWA
From 16-APR-04 21:05:00 to 16-APR-04 21:05:00 (CST)
Location: YALE
Magnitude: 1.00 
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in POLK, IOWA
From 16-APR-04 22:42:00 to 16-APR-04 22:42:00 (CST)
Location: JOHNSTON
Magnitude: 1.00 
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in WEBSTER, IOWA
From 16-APR-04 19:15:00 to 16-APR-04 19:15:00 (CST)
Location: CALLENDER
Magnitude: 0.75 
Reported by: TRAINED SPOTTER

Hail in GUTHRIE, IOWA
From 16-APR-04 20:42:00 to 16-APR-04 20:42:00 (CST)
Location: GUTHRIE CENTER
Magnitude: 1.00 
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in JASPER, IOWA
From 16-APR-04 21:42:00 to 16-APR-04 21:42:00 (CST)
Location: SULLY
Magnitude: 51 MG
Reported by: AWOS,ASOS,MESONET,ETC

Hail in GUTHRIE, IOWA
From 16-APR-04 21:24:00 to 16-APR-04 21:24:00 (CST)
Location: GUTHRIE CENTER ARPT
Magnitude: 1.00 
Property damage: 3K
Reported by: TRAINED SPOTTER

Hail in GUTHRIE, IOWA
From 16-APR-04 21:35:00 to 16-APR-04 21:35:00 (CST)
Location: PANORA
Magnitude: 0.88 
Reported by: GENERAL PUBLIC

Thunderstorm Wind in BOONE, IOWA
From 16-APR-04 20:30:00 to 16-APR-04 20:30:00 (CST)
Location: BOONE
Magnitude: 50 EG
Property damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in POWESHIEK, IOWA
From 16-APR-04 22:13:00 to 16-APR-04 22:13:00 (CST)
Location: BROOKLYN
Magnitude: 52 EG
Reported by: TRAINED SPOTTER