Supercell thunderstorms developed in the evening hours and formed an organized cluster around Waterloo, Iowa.  As the storms moved southeast through Eastern Iowa they interacted with boundaries and produced 6 tornadoes with widespread wind damage in the Cedar Rapids metropolitan area.  KCRG TV and KGAN TV in Cedar Rapids measured 63 knots (73 mph) and 53 knots (61 mph) respectively at their studios during the storm.  At the height of the storm in Cedar Rapids, Alliant Energy reported that about half of its 70,000 customers in the Cedar Rapids area were without power.  Sporatic wind damage then occurred from Cedar Rapids to the Mississippi River.  Heavy rain accompanying the storms produced mainly nuisance street flooding in many cities but did result in 2 mudslides, one in Moline, Illinois and another across Illinois 84 just northwest of Mississippi Palisades State Park in Carroll County Illinois.  The second mudslide resulted in a traffic accident with no injuries.  In Muscatine County the storms evolved into a bow echo and then raced East Southeast and produced widespread wind damage with winds estimated at 80 knots or stronger (92 mph) that lasted 10 to 15 minutes across the Illinois Counties of Rock Island, Mercer, and Southern Henry.  An unsubstantiated wind gust of 90 knots (104 mph) occurred at Lock and Dam 16 on the Mississippi River just east of Muscatine, Iowa.  Mercer and Southern Henry counties in Illinois had extensive damage from the bow echo with Galva, Illinois, in southern Henry County  being hardest hit.  An estimated 10,000 to 15,000 people were without power in the affected 3 counties.  High winds of at least 80 knots (92 mph) lasted for nearly 15 minutes in Galva, toppling a grain elevator onto the BNSF railroad mainline.  The combination of the toppled grain elevator and a propane leak caused by the fallen elevator halted rail traffic for 11 hours, delaying 7 or 8 BNSF trains.  Blackhawk College East Campus in Southeast Henry County cancelled classes for several days due to considerable damage with many trees and power lines down.  In Henry County Illinois alone, an estimated 25,000 acres of corn was flattened.

Thunderstorm Wind in CARROLL, ILLINOIS
From 20-JUL-03 23:20:00 to 20-JUL-03 23:27:00 (CST)
Location: SAVANNA
Magnitude: 52 EG
Property damage: 5K
Reported by: LAW ENFORCEMENT

Tree limbs down on Illinois 84

Thunderstorm Wind in WHITESIDE, ILLINOIS
From 20-JUL-03 23:50:00 to 20-JUL-03 23:59:00 (CST)
Location: COLETA
Magnitude: 61 EG
Property damage: 100K
Crop damage: 10K
Reported by: NEWSPAPER

Radio tower at Fire Station downed

Lightning in MERCER, ILLINOIS
From 20-JUL-03 23:51:00 to 20-JUL-03 23:51:00 (CST)
Location: KEITHSBURG
Property damage: 20K
Reported by: LAW ENFORCEMENT

House on fire from lightning strike

Hail in HENRY, ILLINOIS
From 21-JUL-03 00:17:00 to 21-JUL-03 00:17:00 (CST)
Location: GALVA
Magnitude: 0.88 
Property damage: 100K
Reported by: EMERGENCY MANAGER

Thunderstorm Wind in ROCK ISLAND, ILLINOIS
From 20-JUL-03 23:27:00 to 20-JUL-03 23:38:00 (CST)
Location: ILLINOIS CITY
Magnitude: 59 MG
Property damage: 100K
Crop damage: 20K
Reported by: OTHER FEDERAL AGENCY

Lock & Dam 16; unconfirmed gust of 90 knots (104 mph)

Thunderstorm Wind in ROCK ISLAND, ILLINOIS
From 20-JUL-03 23:27:00 to 20-JUL-03 23:50:00 (CST)
Location: COUNTYWIDE
Magnitude: 65 EG
Property damage: 200K
Crop damage: 100K
Reported by: TRAINED SPOTTER

Also reported by emergency manager.  Southwest part of lower Rock Island county from the Mississippi River to just west of Reynolds.  Power lines down with corn flattened.

Thunderstorm Wind in MERCER, ILLINOIS
From 20-JUL-03 23:34:00 to 21-JUL-03 00:10:00 (CST)
Location: COUNTYWIDE
Magnitude: 70 EG
Property damage: 10M
Crop damage: 3M
Reported by: EMERGENCY MANAGER

Also reported by spotters.  Considerable damage in Viola, Hamlet, North Henderson, and Aledo with numerous trees and power lines down.  Large areas of corn flattened.

Thunderstorm Wind in HENRY, ILLINOIS
From 21-JUL-03 00:00:00 to 21-JUL-03 00:40:00 (CST)
Location: COUNTYWIDE
Magnitude: 80 EG
Property damage: 50M
Crop damage: 25M
Reported by: NWS STORM SURVEY

Also reported by law enforcement, spotters, and emergency managers in the southern part of the county.  Extensive damage in Woodhull, Alpha, Nekoma, and Galva.  Law enforcement reported zero visibility at the height of the storm on I-74 with cars blown into the ditches.

Thunderstorm Wind in HENRY, ILLINOIS
From 21-JUL-03 00:00:00 to 21-JUL-03 00:05:00 (CST)
Location: ANNAWAN
Magnitude: 52 EG
Property damage: 10K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Trees down in a separate storm that was not part of the bow echo in Southern Henry County.

Heavy Rain in ROCK ISLAND, ILLINOIS
From 20-JUL-03 22:30:00 to 21-JUL-03 00:30:00 (CST)
Location: MOLINE
Magnitude: 2.08 
Property damage: 2K
Reported by: TRAINED SPOTTER

Street flooding

Heavy Rain in CARROLL, ILLINOIS
From 20-JUL-03 23:17:00 to 20-JUL-03 23:59:00 (CST)
Location: MARCUS
Magnitude: 1.6 
Property damage: 5K
Reported by: NEWSPAPER