A warm, moist, and unstable airmass was in place over Iowa.  The warm front that had produced the convection during the early morning hours of the 8th had become stationary over northern Iowa.  With lifted indices below -10 C. over central Iowa and continued strong moisture advection, thunderstorms erupted over the central and northeast parts of the state during the late afternoon and evening hours.  For the most part, the thunderstorms produced hail during this event.  There were numerous reports of hail of one to two inches in diameter.  Hail reportedly covered the ground in Guthrie County, into parts of Dallas County.  During the later evening hours, the thunderstorms began to sink south and took on a bow echo type configuration, though the line was not a true bow echo.  High winds began to be reported with Cass County being hit the worst.  A swath of damage 7 miles long was reported from west of Lewis to southeast of Lewis.  Embedded in the winds was a small tornado.  The tornado touched down intermittently along the 7 mile path and destroyed or damaged several grain bins and downed numerous trees.  A large corn crib was destroyed southeast of Atlantic and there were numerous reports of trees over highways.  In addition to the hail and high winds, heavy rain occurred from central into parts of west central Iowa.  Flash flooding occurred in Audubon, Guthrie, Madison, and Adair Counties.  Rain fell as the thunderstorms trained and redeveloped repeatedly over the same areas.  Rainfall rates were in the one to three inch per hour range with rainfall total reports of over 4 inches received in a few places in under two hours.  Water flooded over highways, even some U.S. Highways, to as depth of one to two feet.  This resulted in closure of some highways.

Hail in DALLAS, IOWA
From 08-MAY-04 18:49:00 to 08-MAY-04 18:49:00 (CST)
Location: ADEL
Magnitude: 2.00 
Property damage: 25K
Crop damage: 3K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in UNION, IOWA
From 08-MAY-04 21:37:00 to 08-MAY-04 21:37:00 (CST)
Location: AFTON
Magnitude: 61 EG
Property damage: 10K
Reported by: LAW ENFORCEMENT

Hail in GUTHRIE, IOWA
From 08-MAY-04 19:40:00 to 08-MAY-04 19:40:00 (CST)
Location: STUART
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: AMATEUR RADIO

Flash Flood in ADAIR, IOWA
From 08-MAY-04 21:00:00 to 09-MAY-04 01:00:00 (CST)
Location: COUNTYWIDE
Property damage: 50K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in GUTHRIE, IOWA
From 08-MAY-04 17:35:00 to 08-MAY-04 17:35:00 (CST)
Location: YALE
Magnitude: 1.75 
Property damage: 10K
Crop damage: 3K
Reported by: BROADCAST MEDIA

Hail in MADISON, IOWA
From 08-MAY-04 19:11:00 to 08-MAY-04 19:11:00 (CST)
Location: EARLHAM
Magnitude: 1.75 
Property damage: 15K
Crop damage: 3K
Reported by: LAW ENFORCEMENT

Tornado in CASS, IOWA
From 08-MAY-04 20:25:00 to 08-MAY-04 20:25:00 (CST)
Location: LEWIS
Tornado F-scale: F1
Property damage: 100K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Intermittent path through rural areas.

Hail in GUTHRIE, IOWA
From 08-MAY-04 17:11:00 to 08-MAY-04 17:11:00 (CST)
Location: BAGLEY
Magnitude: 0.88 
Property damage: 3K
Crop damage: 2K
Reported by: LAW ENFORCEMENT

Flash Flood in MADISON, IOWA
From 08-MAY-04 20:45:00 to 09-MAY-04 01:00:00 (CST)
Location: COUNTYWIDE
Property damage: 100K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in FRANKLIN, IOWA
From 08-MAY-04 18:05:00 to 08-MAY-04 18:05:00 (CST)
Location: SHEFFIELD
Magnitude: 1.75 
Property damage: 10K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in GREENE, IOWA
From 08-MAY-04 16:04:00 to 08-MAY-04 16:04:00 (CST)
Location: CHURDAN
Magnitude: 0.75 
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in HAMILTON, IOWA
From 08-MAY-04 16:47:00 to 08-MAY-04 16:47:00 (CST)
Location: ELLSWORTH
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in MADISON, IOWA
From 08-MAY-04 19:58:00 to 08-MAY-04 19:58:00 (CST)
Location: WINTERSET
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: AMATEUR RADIO

Hail in MADISON, IOWA
From 08-MAY-04 20:36:00 to 08-MAY-04 20:36:00 (CST)
Location: WINTERSET
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in DALLAS, IOWA
From 08-MAY-04 18:53:00 to 08-MAY-04 18:53:00 (CST)
Location: ADEL
Magnitude: 0.75 
Crop damage: 2K
Reported by: TRAINED SPOTTER

Hail in GUTHRIE, IOWA
From 08-MAY-04 17:26:00 to 08-MAY-04 17:26:00 (CST)
Location: JAMAICA
Magnitude: 0.88 
Property damage: 3K
Crop damage: 5K
Reported by: AMATEUR RADIO

Hail in FRANKLIN, IOWA
From 08-MAY-04 18:28:00 to 08-MAY-04 18:28:00 (CST)
Location: HAMPTON
Magnitude: 0.75 
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in CASS, IOWA
From 08-MAY-04 20:55:00 to 08-MAY-04 20:55:00 (CST)
Location: ANITA
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in CASS, IOWA
From 08-MAY-04 20:52:00 to 08-MAY-04 20:52:00 (CST)
Location: ATLANTIC
Magnitude: 61 EG
Property damage: 25K
Reported by: TRAINED SPOTTER

Hail in DALLAS, IOWA
From 08-MAY-04 18:18:00 to 08-MAY-04 18:18:00 (CST)
Location: ADEL
Magnitude: 1.75 
Property damage: 5K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in DALLAS, IOWA
From 08-MAY-04 18:41:00 to 08-MAY-04 18:41:00 (CST)
Location: WAUKEE
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: AMATEUR RADIO

Thunderstorm Wind in CASS, IOWA
From 08-MAY-04 20:37:00 to 08-MAY-04 20:37:00 (CST)
Location: WIOTA
Magnitude: 56 EG
Property damage: 15K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 08-MAY-04 21:00:00 to 08-MAY-04 21:00:00 (CST)
Location: FONTANELLE
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in MADISON, IOWA
From 08-MAY-04 20:11:00 to 08-MAY-04 20:11:00 (CST)
Location: WINTERSET
Magnitude: 0.88 
Property damage: 3K
Crop damage: 3K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CASS, IOWA
From 08-MAY-04 20:45:00 to 08-MAY-04 20:45:00 (CST)
Location: CUMBERLAND
Magnitude: 61 EG
Property damage: 15K
Reported by: TRAINED SPOTTER

Hail in AUDUBON, IOWA
From 08-MAY-04 18:58:00 to 08-MAY-04 18:58:00 (CST)
Location: GRAY
Magnitude: 1.00 
Property damage: 5K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in CALHOUN, IOWA
From 08-MAY-04 22:39:00 to 08-MAY-04 22:39:00 (CST)
Location: MANSON
Magnitude: 1.00 
Property damage: 5K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in BREMER, IOWA
From 08-MAY-04 15:53:00 to 08-MAY-04 15:53:00 (CST)
Location: READLYN
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in FRANKLIN, IOWA
From 08-MAY-04 18:12:00 to 08-MAY-04 18:12:00 (CST)
Location: SHEFFIELD
Magnitude: 1.75 
Property damage: 10K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 08-MAY-04 20:55:00 to 08-MAY-04 20:55:00 (CST)
Location: FONTANELLE
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Hail in DALLAS, IOWA
From 08-MAY-04 18:54:00 to 08-MAY-04 18:54:00 (CST)
Location: REDFIELD
Magnitude: 1.25 
Property damage: 15K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in CASS, IOWA
From 08-MAY-04 20:46:00 to 08-MAY-04 20:46:00 (CST)
Location: ANITA
Magnitude: 0.75 
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in ADAIR, IOWA
From 08-MAY-04 20:49:00 to 08-MAY-04 20:49:00 (CST)
Location: FONTANELLE
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: EMERGENCY MANAGER

Hail in HAMILTON, IOWA
From 08-MAY-04 16:15:00 to 08-MAY-04 16:15:00 (CST)
Location: ELLSWORTH
Magnitude: 1.75 
Property damage: 5K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in HAMILTON, IOWA
From 08-MAY-04 16:44:00 to 08-MAY-04 16:44:00 (CST)
Location: ELLSWORTH
Magnitude: 0.75 
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in MADISON, IOWA
From 08-MAY-04 19:40:00 to 08-MAY-04 19:40:00 (CST)
Location: WINTERSET
Magnitude: 0.88 
Property damage: 3K
Crop damage: 5K
Reported by: AMATEUR RADIO

Hail in BOONE, IOWA
From 08-MAY-04 18:08:00 to 08-MAY-04 18:08:00 (CST)
Location: MADRID
Magnitude: 0.75 
Crop damage: 3K
Reported by: BROADCAST MEDIA

Hail in WRIGHT, IOWA
From 08-MAY-04 18:24:00 to 08-MAY-04 18:24:00 (CST)
Location: DOWS
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in GREENE, IOWA
From 08-MAY-04 16:49:00 to 08-MAY-04 16:49:00 (CST)
Location: SCRANTON
Magnitude: 1.75 
Property damage: 5K
Crop damage: 5K
Reported by: STORM CHASER

Hail in STORY, IOWA
From 08-MAY-04 15:04:00 to 08-MAY-04 15:11:00 (CST)
Location: AMES
Magnitude: 1.00 
Property damage: 10K
Crop damage: 2K
Reported by: NWS EMPLOYEE(OFF DUTY)

Hail in GUTHRIE, IOWA
From 08-MAY-04 19:36:00 to 08-MAY-04 19:36:00 (CST)
Location: MENLO
Magnitude: 1.75 
Property damage: 15K
Crop damage: 5K
Reported by: FIRE DEPT/RESCUE SQUAD

Hail in DALLAS, IOWA
From 08-MAY-04 18:11:00 to 08-MAY-04 18:11:00 (CST)
Location: ADEL
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in DALLAS, IOWA
From 08-MAY-04 18:28:00 to 08-MAY-04 18:28:00 (CST)
Location: ADEL
Magnitude: 1.25 
Property damage: 5K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in CASS, IOWA
From 08-MAY-04 21:01:00 to 08-MAY-04 21:01:00 (CST)
Location: LEWIS
Magnitude: 0.75 
Crop damage: 3K
Reported by: EMERGENCY MANAGER

Hail in MADISON, IOWA
From 08-MAY-04 19:54:00 to 08-MAY-04 19:54:00 (CST)
Location: WINTERSET ARPT
Magnitude: 1.25 
Property damage: 10K
Crop damage: 3K
Reported by: AMATEUR RADIO

Hail in GUTHRIE, IOWA
From 08-MAY-04 17:32:00 to 08-MAY-04 17:32:00 (CST)
Location: JAMAICA
Magnitude: 1.75 
Property damage: 5K
Crop damage: 5K
Reported by: BROADCAST MEDIA

Hail in DALLAS, IOWA
From 08-MAY-04 19:21:00 to 08-MAY-04 19:21:00 (CST)
Location: DE SOTO
Magnitude: 0.75 
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in GREENE, IOWA
From 08-MAY-04 16:49:00 to 08-MAY-04 16:49:00 (CST)
Location: SCRANTON
Magnitude: 1.00 
Property damage: 10K
Crop damage: 5K
Reported by: AMATEUR RADIO

Hail in CERRO GORDO, IOWA
From 08-MAY-04 18:15:00 to 08-MAY-04 18:15:00 (CST)
Location: DOUGHERTY
Magnitude: 1.75 
Property damage: 3K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in GUTHRIE, IOWA
From 08-MAY-04 18:20:00 to 08-MAY-04 18:20:00 (CST)
Location: GUTHRIE CENTER
Magnitude: 2.00 
Property damage: 20K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in MADISON, IOWA
From 08-MAY-04 18:55:00 to 08-MAY-04 18:55:00 (CST)
Location: EARLHAM
Magnitude: 1.75 
Property damage: 5K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in GUTHRIE, IOWA
From 08-MAY-04 19:35:00 to 08-MAY-04 19:35:00 (CST)
Location: MENLO
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in GUTHRIE, IOWA
From 08-MAY-04 17:31:00 to 08-MAY-04 17:31:00 (CST)
Location: YALE
Magnitude: 1.75 
Property damage: 10K
Crop damage: 5K
Reported by: BROADCAST MEDIA

Flash Flood in AUDUBON, IOWA
From 08-MAY-04 19:40:00 to 09-MAY-04 01:00:00 (CST)
Location: AUDUBON
Property damage: 50K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in HARDIN, IOWA
From 08-MAY-04 16:49:00 to 08-MAY-04 16:49:00 (CST)
Location: RADCLIFFE
Magnitude: 0.88 
Property damage: 3K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in GUTHRIE, IOWA
From 08-MAY-04 17:15:00 to 08-MAY-04 17:15:00 (CST)
Location: BAGLEY
Magnitude: 1.00 
Property damage: 3K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Flash Flood in GUTHRIE, IOWA
From 08-MAY-04 20:15:00 to 09-MAY-04 01:00:00 (CST)
Location: NORTH PORTION
Property damage: 50K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in HARDIN, IOWA
From 08-MAY-04 16:16:00 to 08-MAY-04 16:16:00 (CST)
Location: IOWA FALLS
Magnitude: 1.00 
Property damage: 5K
Crop damage: 3K
Reported by: TRAINED SPOTTER

Hail in BREMER, IOWA
From 08-MAY-04 16:13:00 to 08-MAY-04 16:13:00 (CST)
Location: READLYN
Magnitude: 1.75 
Property damage: 20K
Crop damage: 5K
Reported by: TRAINED SPOTTER