A very unstable airmass was over Iowa during the afternoon of the 3rd.  A cold front sank into northern Iowa during the afternoon.  Numerous outflow boundaries were located over the state from previous convection as well.  Temperatures rose into the mid 80s to low 90s, while dew point readings soared into the upper 70s to low 80s.  By late afternoon, lifted indices were around -15 C., with CAPE values in the 6000 to 8000 J/kg range.  During the day, a strong MCS tracked east across southern Minnesota.  Thunderstorms developed to the southwest of the MCS as it passed and it's outflow boundary interacted with the unstable airmass.  Thunderstorms erupted very quickly during the late afternoon and evening hours.  The main mode of severe weather from the storms was in the form of high winds.  Winds gusted to between 60 and 80 MPH in several locations.  Strong straight line winds blasted the south half of Marshall County, causing considerable damage in the Marshalltown area as well as areas to the south.  There were spotty reports of hail with the system.  Freezing levels being around 15000 feet AGL helped to limit hail size.  The largest reports were of golf ball size hail, though most of the hail was in inch or less in diameter.  There were a few tornadoes during the late afternoon.  One tornado touched down briefly in Hardin County.  Though it tracked through rural areas, it did cause some structural damage to outbuildings and a house south of Radcliffe.  One of the stronger tornadoes of the day touched down near Albion in Marshall County.  The tornado was on the ground for several miles.  Fortunately, it traveled through rural areas and resulted in little damage.  High winds around the supercell associated with the tornado caused much more damage in the form of straight line winds.  Another tornado touched down in Story County northeast of Zearing.  The tornado tracked southeast along its 3 mile long damage path.  The path was about 100 yards wide.  Thirty to forty trees were damaged or destroyed and one outbuilding was destroyed.  Several head of livestock were killed with the outbuilding was destroyed.  There was also significant crop damage along the path of the storm.  High winds also caused damage in Franklin County in the Bradford area.  Two grain bins were destroyed by the high winds.  Flash flooding became an issue by the evening.  Very heavy rainfall fell in areas that had received significant rainfall during the previous 48 hours.  Rainfall of 2 to 4 inches in less than three hours caused flash flooding in Dallas, Warren, and Decatur Counties.  As the thunderstorms moved through Iowa Falls, lightning struck the Police dispatch office, blowing out all of the switching equipment in the building.  Lightning struck a house in Pella during the evening.  It caused damage throughout the house as all of the wiring in the house was destroyed by the surge of electricity.  Several appliances were also destroyed by the strike.  Another house was struck by lightning in Wayne County in Corydon.  The house was set on fire, totally destroying the top story of a two story home.  In Mahaska County, lightning struck a house in Oskaloosa.  The house was started on fire.  The people in the house escaped, however the family dog was seen by firemen in the window of the house.  They were unable to reach her.  Amazingly, the dog found shelter in the shower and firemen were able to rescue her once the fire was extinguished.  The dog was treated and released.  Damage to the house was limited to smoke and water damage.

Hail in GRUNDY, IOWA
From 03-AUG-04 16:10:00 to 03-AUG-04 16:10:00 (CST)
Location: WELLSBURG
Magnitude: 1.75 
Property damage: 5K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in STORY, IOWA
From 03-AUG-04 16:15:00 to 03-AUG-04 16:15:00 (CST)
Location: KELLEY
Magnitude: 0.75 
Crop damage: 5K
Reported by: AMATEUR RADIO

Hail in BOONE, IOWA
From 03-AUG-04 16:17:00 to 03-AUG-04 16:17:00 (CST)
Location: BOONE
Magnitude: 0.75 
Crop damage: 2K
Reported by: AMATEUR RADIO

Tornado in MARSHALL, IOWA
From 03-AUG-04 16:20:00 to 03-AUG-04 16:30:00 (CST)
Location: ALBION
Tornado F-scale: F1
Property damage: 100K
Crop damage: 10K
Reported by: NWS STORM SURVEY

Tornado touched down near Albion and tracked into notheast Marshall County.  Tree and structural damage was reported along the path.

Thunderstorm Wind in HAMILTON, IOWA
From 03-AUG-04 15:43:00 to 03-AUG-04 15:43:00 (CST)
Location: RANDALL
Magnitude: 57 EG
Property damage: 10K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in BLACK HAWK, IOWA
From 03-AUG-04 17:00:00 to 03-AUG-04 17:00:00 (CST)
Location: WATERLOO
Magnitude: 57 EG
Property damage: 10K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in TAMA, IOWA
From 03-AUG-04 17:00:00 to 03-AUG-04 17:00:00 (CST)
Location: MONTOUR
Magnitude: 50 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BLACK HAWK, IOWA
From 03-AUG-04 17:02:00 to 03-AUG-04 17:02:00 (CST)
Location: WATERLOO
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Hail in AUDUBON, IOWA
From 03-AUG-04 18:03:00 to 03-AUG-04 18:03:00 (CST)
Location: AUDUBON
Magnitude: 1.00 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in AUDUBON, IOWA
From 03-AUG-04 18:33:00 to 03-AUG-04 18:33:00 (CST)
Location: AUDUBON
Magnitude: 1.00 
Property damage: 10K
Crop damage: 5K
Reported by: AMATEUR RADIO

Flash Flood in DECATUR, IOWA
From 04-AUG-04 00:30:00 to 04-AUG-04 03:30:00 (CST)
Location: GARDEN GROVE
Property damage: 10K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Tornado in STORY, IOWA
From 03-AUG-04 16:00:00 to 03-AUG-04 16:06:00 (CST)
Location: ZEARING
Tornado F-scale: F1
Property damage: 75K
Crop damage: 15K
Reported by: EMERGENCY MANAGER

Tornado tracked across fields northeast of Zearing and damaged buildings and crops.

Thunderstorm Wind in FRANKLIN, IOWA
From 03-AUG-04 15:10:00 to 03-AUG-04 15:10:00 (CST)
Location: BRADFORD
Magnitude: 61 EG
Property damage: 25K
Crop damage: 5K
Reported by: NEWSPAPER

Lightning in HARDIN, IOWA
From 03-AUG-04 19:00:00 to 03-AUG-04 19:00:00 (CST)
Location: IOWA FALLS
Property damage: 50K
Reported by: NEWSPAPER

Lightning in MARION, IOWA
From 03-AUG-04 20:30:00 to 03-AUG-04 20:30:00 (CST)
Location: PELLA
Property damage: 10K
Reported by: NEWSPAPER

Hail in DECATUR, IOWA
From 03-AUG-04 21:55:00 to 03-AUG-04 21:55:00 (CST)
Location: GARDEN GROVE
Magnitude: 0.75 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in DECATUR, IOWA
From 03-AUG-04 22:00:00 to 03-AUG-04 22:00:00 (CST)
Location: DAVIS CITY
Magnitude: 52 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in BOONE, IOWA
From 03-AUG-04 15:40:00 to 03-AUG-04 15:40:00 (CST)
Location: BOONE MUNI ARPT
Magnitude: 53 MG
Property damage: 2K
Reported by: AWOS,ASOS,MESONET,ETC

Thunderstorm Wind in STORY, IOWA
From 03-AUG-04 15:40:00 to 03-AUG-04 15:40:00 (CST)
Location: ZEARING
Magnitude: 57 EG
Property damage: 10K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Lightning in WAYNE, IOWA
From 03-AUG-04 22:30:00 to 03-AUG-04 22:30:00 (CST)
Location: CORYDON
Property damage: 50K
Reported by: NEWSPAPER

Lightning in MAHASKA, IOWA
From 03-AUG-04 21:00:00 to 03-AUG-04 21:00:00 (CST)
Location: OSKALOOSA
Property damage: 15K
Reported by: NEWSPAPER

Thunderstorm Wind in WAYNE, IOWA
From 03-AUG-04 22:15:00 to 03-AUG-04 22:15:00 (CST)
Location: CLIO
Magnitude: 50 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in WINNEBAGO, IOWA
From 03-AUG-04 14:00:00 to 03-AUG-04 14:00:00 (CST)
Location: SCARVILLE
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in CALHOUN, IOWA
From 03-AUG-04 14:30:00 to 03-AUG-04 14:30:00 (CST)
Location: ROCKWELL CITY
Magnitude: 0.75 
Crop damage: 5K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in CALHOUN, IOWA
From 03-AUG-04 14:30:00 to 03-AUG-04 14:30:00 (CST)
Location: ROCKWELL CITY
Magnitude: 52 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in WEBSTER, IOWA
From 03-AUG-04 14:49:00 to 03-AUG-04 14:49:00 (CST)
Location: CALLENDER
Magnitude: 61 EG
Property damage: 10K
Crop damage: 1K
Reported by: GENERAL PUBLIC

Hail in GREENE, IOWA
From 03-AUG-04 15:03:00 to 03-AUG-04 15:03:00 (CST)
Location: CHURDAN
Magnitude: 0.75 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in GREENE, IOWA
From 03-AUG-04 15:10:00 to 03-AUG-04 15:10:00 (CST)
Location: CHURDAN
Magnitude: 1.00 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in GREENE, IOWA
From 03-AUG-04 15:15:00 to 03-AUG-04 15:15:00 (CST)
Location: DANA
Magnitude: 0.88 
Crop damage: 5K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in HARDIN, IOWA
From 03-AUG-04 15:47:00 to 03-AUG-04 15:47:00 (CST)
Location: RADCLIFFE
Magnitude: 57 EG
Property damage: 10K
Crop damage: 2K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in STORY, IOWA
From 03-AUG-04 15:50:00 to 03-AUG-04 15:50:00 (CST)
Location: ROLAND
Magnitude: 52 EG
Property damage: 3K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in HARDIN, IOWA
From 03-AUG-04 15:50:00 to 03-AUG-04 15:50:00 (CST)
Location: ELDORA
Magnitude: 52 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Hail in BOONE, IOWA
From 03-AUG-04 15:51:00 to 03-AUG-04 15:51:00 (CST)
Location: PILOT MOUND
Magnitude: 1.00 
Property damage: 5K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Tornado in HARDIN, IOWA
From 03-AUG-04 15:53:00 to 03-AUG-04 15:55:00 (CST)
Location: HUBBARD
Tornado F-scale: F0
Property damage: 20K
Crop damage: 1K
Reported by: FIRE DEPT/RESCUE SQUAD

Brief touchdown in open fields for the most part.  Moved a camper and caused some damage to outbuildings and a house south of Radcliffe.

Thunderstorm Wind in STORY, IOWA
From 03-AUG-04 15:55:00 to 03-AUG-04 15:55:00 (CST)
Location: MC CALLSBURG
Magnitude: 52 EG
Property damage: 3K
Reported by: BROADCAST MEDIA

Hail in BOONE, IOWA
From 03-AUG-04 16:00:00 to 03-AUG-04 16:00:00 (CST)
Location: BOONE
Magnitude: 0.75 
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in STORY, IOWA
From 03-AUG-04 16:00:00 to 03-AUG-04 16:00:00 (CST)
Location: STORY CITY
Magnitude: 52 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in GRUNDY, IOWA
From 03-AUG-04 16:10:00 to 03-AUG-04 16:10:00 (CST)
Location: WELLSBURG
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MARSHALL, IOWA
From 03-AUG-04 16:27:00 to 03-AUG-04 16:27:00 (CST)
Location: MARSHALLTOWN
Magnitude: 57 EG
Property damage: 50K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MARSHALL, IOWA
From 03-AUG-04 16:30:00 to 03-AUG-04 16:30:00 (CST)
Location: MARSHALLTOWN
Magnitude: 57 EG
Property damage: 100K
Crop damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in MARSHALL, IOWA
From 03-AUG-04 16:30:00 to 03-AUG-04 16:30:00 (CST)
Location: LISCOMB
Magnitude: 57 EG
Property damage: 25K
Crop damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in MARSHALL, IOWA
From 03-AUG-04 16:30:00 to 03-AUG-04 16:30:00 (CST)
Location: ALBION
Magnitude: 52 EG
Property damage: 10K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in GRUNDY, IOWA
From 03-AUG-04 16:37:00 to 03-AUG-04 16:37:00 (CST)
Location: DIKE
Magnitude: 61 EG
Property damage: 25K
Crop damage: 10K
Reported by: TRAINED SPOTTER

Hail in STORY, IOWA
From 03-AUG-04 16:39:00 to 03-AUG-04 16:39:00 (CST)
Location: MAXWELL
Magnitude: 1.00 
Property damage: 10K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in BLACK HAWK, IOWA
From 03-AUG-04 16:40:00 to 03-AUG-04 16:40:00 (CST)
Location: CEDAR FALLS
Magnitude: 61 EG
Property damage: 15K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MARSHALL, IOWA
From 03-AUG-04 16:40:00 to 03-AUG-04 16:40:00 (CST)
Location: ALBION
Magnitude: 61 EG
Property damage: 25K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in CARROLL, IOWA
From 03-AUG-04 16:40:00 to 03-AUG-04 16:43:00 (CST)
Location: CARROLL
Magnitude: 0.75 
Crop damage: 10K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in HARDIN, IOWA
From 03-AUG-04 15:18:00 to 03-AUG-04 15:18:00 (CST)
Location: IOWA FALLS
Magnitude: 70 EG
Property damage: 25K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in FRANKLIN, IOWA
From 03-AUG-04 15:20:00 to 03-AUG-04 15:20:00 (CST)
Location: HAMPTON
Magnitude: 65 EG
Property damage: 40K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in FRANKLIN, IOWA
From 03-AUG-04 18:40:00 to 03-AUG-04 18:40:00 (CST)
Location: HAMPTON
Magnitude: 50 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in GUTHRIE, IOWA
From 03-AUG-04 18:45:00 to 03-AUG-04 18:45:00 (CST)
Location: GUTHRIE CENTER
Magnitude: 0.75 
Crop damage: 5K
Reported by: GENERAL PUBLIC

Thunderstorm Wind in DALLAS, IOWA
From 03-AUG-04 19:00:00 to 03-AUG-04 19:00:00 (CST)
Location: DE SOTO
Magnitude: 52 EG
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CASS, IOWA
From 03-AUG-04 19:10:00 to 03-AUG-04 19:10:00 (CST)
Location: GRISWOLD
Magnitude: 50 EG
Property damage: 5K
Reported by: FIRE DEPT/RESCUE SQUAD

Flash Flood in WARREN, IOWA
From 03-AUG-04 19:30:00 to 03-AUG-04 22:30:00 (CST)
Location: INDIANOLA
Property damage: 50K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Flash Flood in DALLAS, IOWA
From 03-AUG-04 19:45:00 to 03-AUG-04 23:30:00 (CST)
Location: DE SOTO
Property damage: 10K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in WARREN, IOWA
From 03-AUG-04 19:45:00 to 03-AUG-04 19:45:00 (CST)
Location: MILO
Magnitude: 52 EG
Property damage: 2K
Reported by: GENERAL PUBLIC

Thunderstorm Wind in MARION, IOWA
From 03-AUG-04 20:24:00 to 03-AUG-04 20:24:00 (CST)
Location: KNOXVILLE
Magnitude: 52 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in LUCAS, IOWA
From 03-AUG-04 20:40:00 to 03-AUG-04 20:40:00 (CST)
Location: WILLIAMSON
Magnitude: 57 EG
Property damage: 5K
Crop damage: 1K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in ADAMS, IOWA
From 03-AUG-04 21:05:00 to 03-AUG-04 21:05:00 (CST)
Location: CORNING
Magnitude: 50 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in TAYLOR, IOWA
From 03-AUG-04 21:20:00 to 03-AUG-04 21:20:00 (CST)
Location: NEW MARKET
Magnitude: 50 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in TAMA, IOWA
From 03-AUG-04 17:10:00 to 03-AUG-04 17:10:00 (CST)
Location: TOLEDO
Magnitude: 52 EG
Property damage: 10K
Reported by: NEWSPAPER

Thunderstorm Wind in MARSHALL, IOWA
From 03-AUG-04 16:05:00 to 03-AUG-04 16:05:00 (CST)
Location: STATE CENTER
Magnitude: 54 EG
Property damage: 5K
Reported by: NEWSPAPER

Thunderstorm Wind in HARDIN, IOWA
From 03-AUG-04 15:24:00 to 03-AUG-04 15:24:00 (CST)
Location: IOWA FALLS
Magnitude: 57 EG
Property damage: 15K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 03-AUG-04 15:30:00 to 03-AUG-04 15:30:00 (CST)
Location: PILOT MOUND
Magnitude: 52 EG
Property damage: 2K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in FRANKLIN, IOWA
From 03-AUG-04 15:35:00 to 03-AUG-04 15:35:00 (CST)
Location: HAMPTON
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER