A very unstable airmass was located over Iowa on the 26th.  Surface dew points rose into the mid to upper 70s along with surface temperatures near 90.  Soundings indicated CAPE values around 5000 J/kg with lifted indices in the -9 C. range.  The freezing level was relatively low, being a little over 12,000 feet.  A steep lapse rate was in place with a 7 to 8 C. lapse rate between 850 and 500 mb.  At the same time, a strong west to southwest jet in excess of 75 kts was in place over the central U.S.  During the afternoon, a cold front dropped southeast into the state.  Thunderstorms erupted during the late afternoon in advance of the cold front.  The storms became severe very quickly and produced high winds and hail.  There were a few tornadoes reported with the stronger storms.  They touched down in open countryside and resulted in little damage.  One tornado northwest of Maxwell in Story County tracked across the north end of a farmstead there.  Several trees were downed and one window was blown out of the farm house.  A tornado touched down in Marshall County south of Melbourne.  The tornado may have actually been three separate tornadoes that developed and dissipated very rapidly.  It was hard to distinguish if there were three, or if the damage path was produced by vortices rotating around the parent storm.  There were three areas along the path of more noticeable damage.  One was of F0 strength, the other two areas were F1 strength.  The entire event took place in about 5 minutes.   High winds and hail were widespread during the event.  There was some very impressive hail reported.  Very large hail of five and one half inches in diameter fell in Hancock County in the Kanawha area.  Incredibly, three inch diameter hail fell in the same area about 30 minutes before the very large hail hit.  The hail resulted in considerable vehicle and home damage in the area.  There were reports of baseball size hail in Pocahontas County near Gilmore City.  Reports from Sac County indicated two and one half inch diameter hail in the town of Odebolt.  The hail did considerable damage in the city, including smashing out the windows in several homes and smashing car windshields.  Most of the other hail reported around the state was golf ball and smaller size.  Many of the storms produced high winds, resulting in a lot of tree and power line damage.  Storms in central Iowa produced 60 to 75 MPH winds, resulting in many cars being blown off highways in central Iowa.  Flash flooding occurred in Davis County as heavy rainfall of 3 to 4 inches fell on the already saturated county.  This weather system was the third heavy rainfall to hit the county in as many days.  County officials reported numerous roads closed to flowing water over the highways, even as sunrise approached.

Hail in CRAWFORD, IOWA
From 26-AUG-04 17:50:00 to 26-AUG-04 17:50:00 (CST)
Location: KIRON
Magnitude: 1.75 
Property damage: 10K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in SAC, IOWA
From 26-AUG-04 17:57:00 to 26-AUG-04 17:57:00 (CST)
Location: ODEBOLT
Magnitude: 1.75 
Property damage: 10K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in AUDUBON, IOWA
From 26-AUG-04 18:05:00 to 26-AUG-04 18:05:00 (CST)
Location: EXIRA
Magnitude: 50 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Hail in SAC, IOWA
From 26-AUG-04 18:17:00 to 26-AUG-04 18:17:00 (CST)
Location: LAKE VIEW
Magnitude: 0.88 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 26-AUG-04 18:21:00 to 26-AUG-04 18:21:00 (CST)
Location: OGDEN
Magnitude: 52 EG
Property damage: 2K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in BOONE, IOWA
From 26-AUG-04 18:27:00 to 26-AUG-04 18:27:00 (CST)
Location: OGDEN
Magnitude: 61 EG
Property damage: 5K
Crop damage: 1K
Reported by: EMERGENCY MANAGER

Hail in TAYLOR, IOWA
From 26-AUG-04 18:30:00 to 26-AUG-04 18:30:00 (CST)
Location: GRAVITY
Magnitude: 0.75 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in TAYLOR, IOWA
From 26-AUG-04 18:34:00 to 26-AUG-04 18:34:00 (CST)
Location: BEDFORD
Magnitude: 52 EG
Property damage: 1K
Reported by: AMATEUR RADIO

Hail in BOONE, IOWA
From 26-AUG-04 18:35:00 to 26-AUG-04 18:35:00 (CST)
Location: OGDEN
Magnitude: 0.88 
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Hail in BOONE, IOWA
From 26-AUG-04 18:45:00 to 26-AUG-04 18:45:00 (CST)
Location: BOONE
Magnitude: 0.88 
Property damage: 1K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 26-AUG-04 18:45:00 to 26-AUG-04 18:45:00 (CST)
Location: BOONE
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 26-AUG-04 18:50:00 to 26-AUG-04 18:50:00 (CST)
Location: BOONE
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 26-AUG-04 18:50:00 to 26-AUG-04 18:50:00 (CST)
Location: BOONE
Magnitude: 55 MG
Property damage: 5K
Reported by: AWOS,ASOS,MESONET,ETC

Hail in TAYLOR, IOWA
From 26-AUG-04 18:50:00 to 26-AUG-04 18:50:00 (CST)
Location: CONWAY
Magnitude: 0.75 
Crop damage: 5K
Reported by: GENERAL PUBLIC

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:00:00 to 26-AUG-04 19:00:00 (CST)
Location: STORY CITY
Magnitude: 55 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in MARSHALL, IOWA
From 26-AUG-04 20:02:00 to 26-AUG-04 20:02:00 (CST)
Location: GILMAN
Magnitude: 50 EG
Property damage: 1K
Reported by: AMATEUR RADIO

Thunderstorm Wind in TAMA, IOWA
From 26-AUG-04 20:05:00 to 26-AUG-04 20:05:00 (CST)
Location: GLADBROOK
Magnitude: 52 EG
Property damage: 2K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in DECATUR, IOWA
From 26-AUG-04 20:06:00 to 26-AUG-04 20:06:00 (CST)
Location: LE ROY
Magnitude: 57 EG
Property damage: 25K
Crop damage: 1K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in MARSHALL, IOWA
From 26-AUG-04 20:06:00 to 26-AUG-04 20:06:00 (CST)
Location: MARSHALLTOWN ARPT
Magnitude: 54 MG
Property damage: 1K
Reported by: AWOS,ASOS,MESONET,ETC

Hail in RINGGOLD, IOWA
From 26-AUG-04 19:15:00 to 26-AUG-04 19:15:00 (CST)
Location: DIAGONAL
Magnitude: 0.88 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:49:00 to 26-AUG-04 19:49:00 (CST)
Location: COLO
Magnitude: 57 EG
Property damage: 10K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MARSHALL, IOWA
From 26-AUG-04 20:06:00 to 26-AUG-04 20:06:00 (CST)
Location: MARSHALLTOWN
Magnitude: 50 EG
Property damage: 1K
Reported by: AMATEUR RADIO

Thunderstorm Wind in MARSHALL, IOWA
From 26-AUG-04 20:10:00 to 26-AUG-04 20:10:00 (CST)
Location: MARSHALLTOWN
Magnitude: 65 EG
Property damage: 20K
Crop damage: 3K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in JASPER, IOWA
From 26-AUG-04 20:17:00 to 26-AUG-04 20:17:00 (CST)
Location: BAXTER
Magnitude: 50 EG
Property damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in JASPER, IOWA
From 26-AUG-04 20:17:00 to 26-AUG-04 20:17:00 (CST)
Location: BAXTER
Magnitude: 50 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in TAMA, IOWA
From 26-AUG-04 20:19:00 to 26-AUG-04 20:19:00 (CST)
Location: TAMA
Magnitude: 57 EG
Property damage: 5K
Crop damage: 1K
Reported by: LAW ENFORCEMENT

Tornado in STORY, IOWA
From 26-AUG-04 19:25:00 to 26-AUG-04 19:25:00 (CST)
Location: MAXWELL
Tornado F-scale: F0
Property damage: 10K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Tornado tracked through the north end of a farmstead resulting in tree damage.  One window was blown out of the farmhouse.

Thunderstorm Wind in UNION, IOWA
From 26-AUG-04 20:30:00 to 26-AUG-04 20:30:00 (CST)
Location: AFTON
Magnitude: 57 EG
Property damage: 10K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MARSHALL, IOWA
From 26-AUG-04 20:30:00 to 26-AUG-04 20:30:00 (CST)
Location: GILMAN
Magnitude: 57 EG
Property damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in UNION, IOWA
From 26-AUG-04 20:32:00 to 26-AUG-04 20:32:00 (CST)
Location: AFTON
Magnitude: 52 EG
Property damage: 10K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in UNION, IOWA
From 26-AUG-04 20:35:00 to 26-AUG-04 20:35:00 (CST)
Location: AFTON
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BLACK HAWK, IOWA
From 26-AUG-04 20:35:00 to 26-AUG-04 20:35:00 (CST)
Location: HUDSON
Magnitude: 52 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in WAYNE, IOWA
From 26-AUG-04 20:35:00 to 26-AUG-04 20:35:00 (CST)
Location: HUMESTON
Magnitude: 52 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in BLACK HAWK, IOWA
From 26-AUG-04 20:36:00 to 26-AUG-04 20:36:00 (CST)
Location: ELK RUN HGTS
Magnitude: 57 EG
Property damage: 10K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in DECATUR, IOWA
From 26-AUG-04 20:38:00 to 26-AUG-04 20:38:00 (CST)
Location: GARDEN GROVE
Magnitude: 50 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in BLACK HAWK, IOWA
From 26-AUG-04 20:45:00 to 26-AUG-04 20:45:00 (CST)
Location: EVANSDALE
Magnitude: 52 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Hail in CLARKE, IOWA
From 26-AUG-04 20:45:00 to 26-AUG-04 20:45:00 (CST)
Location: MURRAY
Magnitude: 0.75 
Crop damage: 3K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MARSHALL, IOWA
From 26-AUG-04 20:52:00 to 26-AUG-04 20:52:00 (CST)
Location: FERGUSON
Magnitude: 52 EG
Property damage: 2K
Reported by: AMATEUR RADIO

Thunderstorm Wind in DECATUR, IOWA
From 26-AUG-04 21:24:00 to 26-AUG-04 21:24:00 (CST)
Location: LEON
Magnitude: 57 EG
Property damage: 10K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in POLK, IOWA
From 26-AUG-04 19:00:00 to 26-AUG-04 19:00:00 (CST)
Location: ALLEMAN
Magnitude: 52 EG
Property damage: 2K
Reported by: NWS EMPLOYEE(OFF DUTY)

Thunderstorm Wind in BOONE, IOWA
From 26-AUG-04 19:05:00 to 26-AUG-04 19:05:00 (CST)
Location: MADRID
Magnitude: 52 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:09:00 to 26-AUG-04 19:09:00 (CST)
Location: AMES
Magnitude: 50 EG
Property damage: 1K
Reported by: AMATEUR RADIO

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:15:00 to 26-AUG-04 19:15:00 (CST)
Location: HUXLEY
Magnitude: 65 EG
Property damage: 25K
Crop damage: 10K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in BOONE, IOWA
From 26-AUG-04 19:15:00 to 26-AUG-04 19:15:00 (CST)
Location: LUTHER
Magnitude: 61 EG
Property damage: 5K
Crop damage: 1K
Reported by: EMERGENCY MANAGER

Tornado in HUMBOLDT, IOWA
From 26-AUG-04 16:00:00 to 26-AUG-04 16:00:00 (CST)
Location: HUMBOLDT
Tornado F-scale: F0
Crop damage: 2K
Reported by: TRAINED SPOTTER

Tornado touched down in open fields north of Humboldt and caused little damage.

Hail in HANCOCK, IOWA
From 26-AUG-04 16:00:00 to 26-AUG-04 16:00:00 (CST)
Location: KANAWHA
Magnitude: 5.50 
Property damage: 100K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in CERRO GORDO, IOWA
From 26-AUG-04 16:13:00 to 26-AUG-04 16:13:00 (CST)
Location: VENTURA
Magnitude: 0.88 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:00:00 to 26-AUG-04 19:00:00 (CST)
Location: AMES
Magnitude: 50 EG
Property damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in DECATUR, IOWA
From 26-AUG-04 21:30:00 to 26-AUG-04 21:30:00 (CST)
Location: DECATUR CITY
Magnitude: 52 EG
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in STORY, IOWA
From 26-AUG-04 19:15:00 to 26-AUG-04 19:15:00 (CST)
Location: KELLEY
Magnitude: 0.88 
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:15:00 to 26-AUG-04 19:15:00 (CST)
Location: KELLEY
Magnitude: 61 EG
Property damage: 5K
Crop damage: 1K
Reported by: EMERGENCY MANAGER

Hail in BOONE, IOWA
From 26-AUG-04 19:15:00 to 26-AUG-04 19:15:00 (CST)
Location: LUTHER
Magnitude: 0.88 
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:15:00 to 26-AUG-04 19:15:00 (CST)
Location: AMES
Magnitude: 50 EG
Property damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in RINGGOLD, IOWA
From 26-AUG-04 19:15:00 to 26-AUG-04 19:15:00 (CST)
Location: DIAGONAL
Magnitude: 57 EG
Property damage: 5K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Tornado in STORY, IOWA
From 26-AUG-04 19:13:00 to 26-AUG-04 19:13:00 (CST)
Location: MAXWELL
Tornado F-scale: F0
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Tornado caused relatively little damage as it tracked through open country.

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:26:00 to 26-AUG-04 19:26:00 (CST)
Location: AMES
Magnitude: 57 EG
Property damage: 10K
Crop damage: 1K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in STORY, IOWA
From 26-AUG-04 19:35:00 to 26-AUG-04 19:35:00 (CST)
Location: COLLINS
Magnitude: 52 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Hail in RINGGOLD, IOWA
From 26-AUG-04 19:40:00 to 26-AUG-04 19:40:00 (CST)
Location: MT AYR
Magnitude: 0.75 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in DECATUR, IOWA
From 26-AUG-04 19:45:00 to 26-AUG-04 19:45:00 (CST)
Location: GRAND RIVER
Magnitude: 1.00 
Property damage: 5K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in DECATUR, IOWA
From 26-AUG-04 19:45:00 to 26-AUG-04 19:45:00 (CST)
Location: GRAND RIVER
Magnitude: 57 EG
Property damage: 10K
Crop damage: 1K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in MONROE, IOWA
From 26-AUG-04 22:20:00 to 26-AUG-04 22:20:00 (CST)
Location: ALBIA
Magnitude: 52 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in WAPELLO, IOWA
From 26-AUG-04 22:32:00 to 26-AUG-04 22:32:00 (CST)
Location: CHILLICOTHE
Magnitude: 50 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in WAPELLO, IOWA
From 26-AUG-04 22:34:00 to 26-AUG-04 22:34:00 (CST)
Location: EDDYVILLE
Magnitude: 52 EG
Property damage: 5K
Reported by: EMERGENCY MANAGER

Flash Flood in DAVIS, IOWA
From 27-AUG-04 01:00:00 to 27-AUG-04 06:15:00 (CST)
Location: COUNTYWIDE
Property damage: 100K
Crop damage: 25K
Reported by: LAW ENFORCEMENT

Tornado in MARSHALL, IOWA
From 26-AUG-04 19:40:00 to 26-AUG-04 19:45:00 (CST)
Location: MELBOURNE
Tornado F-scale: F1
Property damage: 50K
Crop damage: 10K
Reported by: NWS STORM SURVEY

Tornado had an intermittent track and may have infact been three tornadoes that developed in rapid succesion.

Thunderstorm Wind in APPANOOSE, IOWA
From 26-AUG-04 22:25:00 to 26-AUG-04 22:25:00 (CST)
Location: MORAVIA
Magnitude: 57 EG
Property damage: 15K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Hail in SAC, IOWA
From 26-AUG-04 17:58:00 to 26-AUG-04 17:58:00 (CST)
Location: ODEBOLT
Magnitude: 2.50 
Property damage: 50K
Crop damage: 10K
Reported by: GENERAL PUBLIC

Hail in HANCOCK, IOWA
From 26-AUG-04 15:07:00 to 26-AUG-04 15:07:00 (CST)
Location: KANAWHA
Magnitude: 0.75 
Reported by: OFFICIAL NWS OBS.

Hail in HUMBOLDT, IOWA
From 26-AUG-04 15:10:00 to 26-AUG-04 15:10:00 (CST)
Location: HARDY
Magnitude: 0.75 
Reported by: AMATEUR RADIO

Hail in POCAHONTAS, IOWA
From 26-AUG-04 15:17:00 to 26-AUG-04 15:18:00 (CST)
Location: POCAHONTAS
Magnitude: 2.75 
Property damage: 25K
Crop damage: 10K
Reported by: TRAINED SPOTTER

Hail in POCAHONTAS, IOWA
From 26-AUG-04 15:21:00 to 26-AUG-04 15:21:00 (CST)
Location: POCAHONTAS
Magnitude: 1.50 
Property damage: 5K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in HANCOCK, IOWA
From 26-AUG-04 15:27:00 to 26-AUG-04 15:27:00 (CST)
Location: KANAWHA
Magnitude: 3.00 
Property damage: 25K
Crop damage: 10K
Reported by: OFFICIAL NWS OBS.

Hail in HUMBOLDT, IOWA
From 26-AUG-04 15:45:00 to 26-AUG-04 15:45:00 (CST)
Location: BRADGATE
Magnitude: 1.75 
Property damage: 10K
Crop damage: 10K
Reported by: TRAINED SPOTTER

Hail in HUMBOLDT, IOWA
From 26-AUG-04 16:00:00 to 26-AUG-04 16:00:00 (CST)
Location: HUMBOLDT
Magnitude: 1.75 
Property damage: 10K
Crop damage: 15K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in MONROE, IOWA
From 26-AUG-04 21:20:00 to 26-AUG-04 21:20:00 (CST)
Location: MELROSE
Magnitude: 52 EG
Property damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in DECATUR, IOWA
From 26-AUG-04 21:30:00 to 26-AUG-04 21:30:00 (CST)
Location: LEON
Magnitude: 57 EG
Property damage: 10K
Crop damage: 1K
Reported by: EMERGENCY MANAGER