Ingredients were present for a big outbreak of severe weather.  A strong upper level disturbance was moving through the plains.  Meanwhile, surface low pressure raced from Southwest Minnesota into Wisconsin by late afternoon, allowing a strong cold front to sweep into Central Iowa by late in the day.  Ahead of the front, a strong southwest breeze and abundant sunshine pushed temperatures to record levels with readings generally in the mid and upper 90s.  An old outflow boundary from  earlier convection set up over Northeast Iowa and Northern Illinois.  Thunderstorms redeveloped along the boundary by mid to late afternoon over Northeast Iowa and quickly became severe.  The convection took on an east to west orientation, which resulted in training of cells leading to heavy rains in excess of 3 inches, and recurring reports of severe weather.  Meanwhile, thunderstorms exploded late in the afternoon along the approaching cold front from near Des Moines, Iowa to St. Joseph, Missouri.  Strong convective instability and strengthening vertical wind shear profiles resulted in the formation of an intense squall line.  The squall line raced eastward producing numerous reports of large hail and damaging winds.  Several areas lost power.  The storms also did considerable damage to many of the areas corn and soybean crops.  Damage was widespread but variable, with as much as 10 percent of the corn crop damaged in some areas.  Several factors contributed to the damage.  A big factor was the direction of the rows in relation to the wind.  Other factors included the variety of corn, as some were not rooted as deeply, and stalk rot which makes corn stalks brittle and unstable.  Stalk rot was brought on by a wet July and relatively dry August.

Thunderstorm Wind in WHITESIDE, ILLINOIS
From 11-SEP-00 19:35:00 to 11-SEP-00 19:35:00 (CST)
Location: FULTON
Magnitude: 55 E
Reported by: TRAINED SPOTTER

Numerous trees and limbs down.

Thunderstorm Wind in BUREAU, ILLINOIS
From 11-SEP-00 20:30:00 to 11-SEP-00 20:30:00 (CST)
Location: PRINCETON
Magnitude: 52 E
Reported by: LAW ENFORCEMENT

Trees down.

Thunderstorm Wind in WHITESIDE, ILLINOIS
From 11-SEP-00 19:55:00 to 11-SEP-00 19:55:00 (CST)
Location: FULTON
Magnitude: 52 E
Reported by: LAW ENFORCEMENT

Large tree down.

Thunderstorm Wind in HENRY, ILLINOIS
From 11-SEP-00 20:25:00 to 11-SEP-00 20:25:00 (CST)
Location: CAMBRIDGE
Magnitude: 61 M
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CARROLL, ILLINOIS
From 11-SEP-00 18:47:00 to 11-SEP-00 18:54:00 (CST)
Location: MT CARROLL
Magnitude: 55 E
Reported by: LAW ENFORCEMENT

Tree down on Route 64 at Center Hill. Trees also down on North Clay Street and on Jackson Street.

Thunderstorm Wind in JO DAVIESS, ILLINOIS
From 11-SEP-00 18:30:00 to 11-SEP-00 18:30:00 (CST)
Location: COUNTYWIDE
Magnitude: 52 E
Reported by: EMERGENCY MANAGER

Numerous trees down.

Thunderstorm Wind in HENRY, ILLINOIS
From 11-SEP-00 21:00:00 to 11-SEP-00 21:00:00 (CST)
Location: GALVA
Magnitude: 52 E
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CARROLL, ILLINOIS
From 11-SEP-00 18:50:00 to 11-SEP-00 18:50:00 (CST)
Location: MT CARROLL
Magnitude: 52 E
Reported by: LAW ENFORCEMENT

Numerous trees down.

Thunderstorm Wind in CARROLL, ILLINOIS
From 11-SEP-00 20:13:00 to 11-SEP-00 20:17:00 (CST)
Location: MT CARROLL
Magnitude: 52 E
Reported by: LAW ENFORCEMENT

Trees down on Route 64 east of Mount Carroll and along Carroll and Center Streets in Mount Carroll.

Hail in HENRY, ILLINOIS
From 11-SEP-00 21:00:00 to 11-SEP-00 21:00:00 (CST)
Location: GALVA
Magnitude: 0.80 
Reported by: TRAINED SPOTTER

Thunderstorm Wind in CARROLL, ILLINOIS
From 11-SEP-00 20:00:00 to 11-SEP-00 20:00:00 (CST)
Location: MT CARROLL
Property damage: 5K
Reported by: LAW ENFORCEMENT

Windows blown out of a building showroom.

Thunderstorm Wind in HENRY, ILLINOIS
From 11-SEP-00 20:10:00 to 11-SEP-00 20:10:00 (CST)
Location: GENESEO
Property damage: 2K
Reported by: GENERAL PUBLIC

Large tree down.

Thunderstorm Wind in WHITESIDE, ILLINOIS
From 11-SEP-00 19:35:00 to 11-SEP-00 19:35:00 (CST)
Location: MORRISON
Property damage: 2K
Reported by: LAW ENFORCEMENT

Trees down.

Thunderstorm Wind in BUREAU, ILLINOIS
From 11-SEP-00 21:30:00 to 11-SEP-00 21:30:00 (CST)
Location: BUREAU
Magnitude: 52 M
Reported by: TRAINED SPOTTER

Large tree limbs down.

Hail in ROCK ISLAND, ILLINOIS
From 11-SEP-00 20:05:00 to 11-SEP-00 20:05:00 (CST)
Location: ROCK IS
Magnitude: 0.88 
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in CARROLL, ILLINOIS
From 11-SEP-00 20:00:00 to 11-SEP-00 20:00:00 (CST)
Location: MT CARROLL
Property damage: 20K
Reported by: LAW ENFORCEMENT

Corn auger blown onto power lines.

Thunderstorm Wind in WARREN, ILLINOIS
From 11-SEP-00 21:30:00 to 11-SEP-00 21:30:00 (CST)
Location: MONMOUTH
Crop damage: 500K
Reported by: BROADCAST MEDIA

Damaging straight line winds estimated at near 60 mph toppled acres of corn and soybeans in and around Monmouth.

Thunderstorm Wind in HENDERSON, ILLINOIS
From 11-SEP-00 20:20:00 to 11-SEP-00 20:20:00 (CST)
Location: OQUAWKA
Magnitude: 52 E
Reported by: LAW ENFORCEMENT

Numerous trees down.

Thunderstorm Wind in STEPHENSON, ILLINOIS
From 11-SEP-00 20:16:00 to 11-SEP-00 20:16:00 (CST)
Location: LENA
Magnitude: 52 E
Reported by: LAW ENFORCEMENT

Large tree down on Route 73 at Hershey Road.

Thunderstorm Wind in BUREAU, ILLINOIS
From 11-SEP-00 20:30:00 to 11-SEP-00 20:30:00 (CST)
Location: DOVER
Magnitude: 52 E
Reported by: LAW ENFORCEMENT

Large branches and trees down.

Thunderstorm Wind in STEPHENSON, ILLINOIS
From 11-SEP-00 19:20:00 to 11-SEP-00 19:20:00 (CST)
Location: FREEPORT
Magnitude: 52 E
Reported by: LAW ENFORCEMENT

Small trees and branches down.