Storms developed in a moist to near tropical atmosphere along a warm front from Dubuque, Iowa to Falls City, Nebraska, and ahead of a cold front in western Iowa.  A strong low level jet continuously feed moist air into the storms resulting in copious amounts of rain in very short time periods across Eastern Iowa and West Central Illinois.  The additional shear provided by the warm front allowed 3 tornadoes to develop.  As the night progressed, the warm front stalled along the Iowa/Missouri border and became a focus for thunderstorms to train along with very heavy rainfall.

Heavy Rain in IOWA, IOWA
From 26-AUG-04 21:10:00 to 26-AUG-04 23:48:00 (CST)
Location: MARENGO
Reported by: EMERGENCY MANAGER

3 to 4 inches of rain from Marengo to Amana

Thunderstorm Wind in IOWA, IOWA
From 26-AUG-04 21:55:00 to 26-AUG-04 22:00:00 (CST)
Location: LADORA
Magnitude: 61 EG
Property damage: 5K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in BENTON, IOWA
From 26-AUG-04 21:03:00 to 26-AUG-04 21:11:00 (CST)
Location: BELLE PLAINE
Magnitude: 52 EG
Property damage: 3K
Crop damage: 2K
Reported by: EMERGENCY MANAGER

Power out

Thunderstorm Wind in BENTON, IOWA
From 26-AUG-04 21:05:00 to 26-AUG-04 21:10:00 (CST)
Location: ATKINS
Magnitude: 61 EG
Property damage: 5K
Crop damage: 5K
Reported by: NWS STORM SURVEY

A narrow swath of tree damage, siding blown off houses, and a collapsed garage (due to vehicle door failure) occurred in Atkins consistent with straight line winds around 70 mph.

Thunderstorm Wind in LINN, IOWA
From 26-AUG-04 21:10:00 to 26-AUG-04 21:15:00 (CST)
Location: PALO
Magnitude: 52 EG
Property damage: 3K
Reported by: EMERGENCY MANAGER

Power out

Heavy Rain in IOWA, IOWA
From 26-AUG-04 21:10:00 to 26-AUG-04 23:48:00 (CST)
Location: LADORA
Magnitude: 3 
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in LINN, IOWA
From 26-AUG-04 21:35:00 to 26-AUG-04 21:40:00 (CST)
Location: MARION ARPT
Magnitude: 65 EG
Property damage: 20K
Crop damage: 10K
Reported by: NEWSPAPER

Roof damage to a farm house with a barn collapsed.  The barn collapse occurred after the main door had been blown inward. An aerial view indicated a fan shaped pattern of damage indicative of a downburst or microburst.

Thunderstorm Wind in LINN, IOWA
From 26-AUG-04 21:20:00 to 26-AUG-04 21:24:00 (CST)
Location: HIAWATHA
Magnitude: 61 EG
Property damage: 20K
Reported by: NWS STORM SURVEY

A mile long swath of straight line winds estimated at 70 mph occurred along Boyson Road in the northern part of Hiawatha.  Damage was sustained to the local Farm Bureau office, the Hiawatha Care Center, a gas station, a banking center, and a sign company.  A 91 year old female resident of the Care Center was injured when part of the wall was knocked out with damage to the roof.

Thunderstorm Wind in DELAWARE, IOWA
From 26-AUG-04 21:27:00 to 26-AUG-04 21:35:00 (CST)
Location: COLESBURG
Magnitude: 52 EG
Property damage: 2K
Crop damage: 2K
Reported by: TRAINED SPOTTER

Heavy Rain in LINN, IOWA
From 26-AUG-04 21:21:00 to 26-AUG-04 22:21:00 (CST)
Location: CEDAR RAPIDS
Magnitude: 2 
Reported by: TRAINED SPOTTER

2 inches in one hour

Thunderstorm Wind in JACKSON, IOWA
From 26-AUG-04 22:31:00 to 26-AUG-04 22:36:00 (CST)
Location: BELLEVUE
Magnitude: 52 EG
Property damage: 2K
Reported by: LAW ENFORCEMENT

Funnel Cloud in DUBUQUE, IOWA
From 26-AUG-04 22:01:00 to 26-AUG-04 22:01:00 (CST)
Location: DYERSVILLE
Reported by: FIRE DEPT/RESCUE SQUAD

Location is actually in Eastern Delaware County 4.2 miles northwest of Worthington.  Spotters from the Dyersville Fire Department and in Worthington briefly glimpsed the Hopkinton Tornado as it roped out and dissipated on the horizon.

Flash Flood in IOWA, IOWA
From 26-AUG-04 22:15:00 to 27-AUG-04 01:00:00 (CST)
Location: MIDDLE AMANA
Magnitude: 5 
Property damage: 40K
Crop damage: 5K
Reported by: FIRE DEPT/RESCUE SQUAD

Between 2145 CST and 2245 CST, spotters reported that 4.5 to 5.5 inches of rain fell in the Amana's Colonies in Northeast Iowa County.  A road was closed due to high water in Middle Amana and a nursing home was flooded with water up to 6 inches deep, including the kitchen and welcome areas.  A small recreational dam on a pond between Middle Amana and High Amana broke flooding the immediate area.

Flash Flood in VAN BUREN, IOWA
From 27-AUG-04 00:15:00 to 27-AUG-04 07:00:00 (CST)
Location: SOUTH PORTION
Magnitude: 5.5 
Property damage: 50K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorms trained across southern Van Buren County producing rainfall rates of up to 1.5 inches per hour.  Ground truth reports indicated anywhere from 3.5 to 6 inches of rain.  A house between Cantril and Mt Sterling had its basement flooded.  The 290th Street Bridge located between Underwood and Timber Avenues southwest of Farmington collapsed after the embankments were washed away due to the flood waters.

Thunderstorm Wind in LINN, IOWA
From 26-AUG-04 21:29:00 to 26-AUG-04 21:33:00 (CST)
Location: FAIRFAX
Magnitude: 57 EG
Property damage: 10K
Reported by: EMERGENCY MANAGER

Water ponding on the road heading toward Walford.  Roof damage to a gas station with some windows broken out.