Strong low pressure in southeast Colorado moved to eastern Iowa during the early afternoon of November 22, 2010. The deepening cyclone then moved to northern Lake Michigan by evening. There was a tremendous thermal gradient with temperatures below zero in the northern Plains, with 60s and 70s from the southern Plains to Lower Michigan. A squall line formed in advance of the intense cold front impacting extreme eastern Iowa and western Illinois. Impressive deep layer shear and very strong wind fields triggered several intense supercells, especially in Illinois. Hail up to the size of hen eggs and winds in excess of 70 mph were reported in western Illinois during the afternoon. An intense supercell moved rapidly northeast at 60 mph across portions of southeast Henry county in western Illinois. This storm produced a swath of significant downburst wind damage from 1 mile south of Galva to 3 miles southeast of Kewanee. Trees were snapped or uprooted and several outbuildings damaged or destroyed. A NWS survey showed the damage swath was one-half mile wide in some areas. Wind speeds were estimated at 80 to 100 mph.

Thunderstorm Wind in MCDONOUGH, ILLINOIS
From 22-NOV-10 14:20:00 to 22-NOV-10 14:20:00 (CST-6)
Location: NEW PHILADELPHIA
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported trees and power lines down 2 miles southwest of New Philadelphia. Winds were estimated at over 70 mph.

Thunderstorm Wind in WHITESIDE, ILLINOIS
From 22-NOV-10 14:28:00 to 22-NOV-10 14:28:00 (CST-6)
Location: ROCK FALLS
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported trees and power lines down on Rock Island Road near Rock Falls. Winds were estimated at over 70 mph.

Hail in WARREN, ILLINOIS
From 22-NOV-10 12:51:00 to 22-NOV-10 12:51:00 (CST-6)
Location: MONMOUTH
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter meaured hail to penny size near Monmouth.

Hail in HENDERSON, ILLINOIS
From 22-NOV-10 13:50:00 to 22-NOV-10 13:50:00 (CST-6)
Location: RARITAN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated hail to penny size and 50 mph winds 1 mile north of Raritan.

Hail in BUREAU, ILLINOIS
From 22-NOV-10 14:05:00 to 22-NOV-10 14:05:00 (CST-6)
Location: SHEFFIELD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The emergency manager reported hail to quarter size in Sheffield.

Thunderstorm Wind in HENRY, ILLINOIS
From 22-NOV-10 14:09:00 to 22-NOV-10 14:09:00 (CST-6)
Location: GALVA
Magnitude: 80.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported several trees and power poles damaged, as well as some structural damage mainly south and southeast of Galva. Some semi-trucks were also overturned.  Winds were estimated at 90 mph.

Hail in HENDERSON, ILLINOIS
From 22-NOV-10 12:15:00 to 22-NOV-10 12:15:00 (CST-6)
Location: LOMAX
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated hail the size of hen eggs 4 miles southwest of Carman.

Hail in HENDERSON, ILLINOIS
From 22-NOV-10 12:45:00 to 22-NOV-10 12:45:00 (CST-6)
Location: BIGGSVILLE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Fire department estimated hail to quarter size 2 miles east of Biggsville.

Thunderstorm Wind in HENRY, ILLINOIS
From 22-NOV-10 02:20:00 to 22-NOV-10 02:20:00 (CST-6)
Location: KEWANEE
Magnitude: 80.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported 40 to 50 evergreen trees, 35 to 60 feet tall, broken off at the 20 foot level near Kewanee. Winds were estimated at over 90 mph.

Thunderstorm Wind in HENRY, ILLINOIS
From 22-NOV-10 14:00:00 to 22-NOV-10 14:20:00 (CST-6)
Location: GALVA
Magnitude: 87.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A supercell tracked across portions of Henry county producing a swath of straight-line downburst winds as the thunderstorm moved rapidly to the northeast at 60 mph.
Tree damage was first noted at the Galva cemetery near the county line, where roughly 10 pine trees were either snapped at the base or uprooted. The largest of which was 2 feet in diameter and tossed 25 yards to the east.  About a dozen of the taller headstones were toppled from their bases.  Farther to the northeast, sheet metal was torn from the roof of a Tyson building, and scattered into the surrounding fields a quarter mile to the east. Off of Route 78 southeast of Kewanee, a half dozen pine trees were snapped at the trunk with surrounding tall grass matted down to the east.  Farther down the road to the east a corn crib was destroyed when it shifted off it's foundation. Continuing to the east, there were roughly 40 trees in a 35 year old wind break that were snapped at the trunks. There was also hail damage noted with chipped paint on west facing walls and scarred tree trunks. Ending 3 miles east southeast of Kewanee a barn roof was mostly ripped off, scattering debris a couple hundred yards to the east.  Based on the damage, winds were estimated to be between 80 to 100 mph.  At some locations the damage swath was one-half mile wide in southeast Henry county, Illinois.

Hail in HANCOCK, ILLINOIS
From 22-NOV-10 12:10:00 to 22-NOV-10 12:10:00 (CST-6)
Location: DALLAS CITY
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured hail to penny size in Dallas City.

Hail in HANCOCK, ILLINOIS
From 22-NOV-10 12:06:00 to 22-NOV-10 12:06:00 (CST-6)
Location: DALLAS CITY
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement estimated hail to half dollar size in Dallas City.

Hail in BUREAU, ILLINOIS
From 22-NOV-10 14:00:00 to 22-NOV-10 14:00:00 (CST-6)
Location: SHEFFIELD
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported golf ball size hail in Sheffield.

Hail in HENRY, ILLINOIS
From 22-NOV-10 14:11:00 to 22-NOV-10 14:11:00 (CST-6)
Location: GALVA
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The emergency manager reported golf ball size hail in Galva.

Hail in HENRY, ILLINOIS
From 22-NOV-10 14:08:00 to 22-NOV-10 14:08:00 (CST-6)
Location: GALVA
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated hail to penny size in Galva.

Hail in HENRY, ILLINOIS
From 22-NOV-10 14:14:00 to 22-NOV-10 14:14:00 (CST-6)
Location: KEWANEE MUNI ARPT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated quarter size hail 3 miles south of Kewanee.

Thunderstorm Wind in HENRY, ILLINOIS
From 22-NOV-10 14:14:00 to 22-NOV-10 14:14:00 (CST-6)
Location: KEWANEE MUNI ARPT
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated wind gusts to 70 mph 5 miles south of Kewanee.

Hail in HENRY, ILLINOIS
From 22-NOV-10 14:15:00 to 22-NOV-10 14:15:00 (CST-6)
Location: KEWANEE MUNI ARPT
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

WGEM-TV reported ping pong ball size hail 5 miles south of Kewanee near Routes 91 and 17.

Thunderstorm Wind in HENRY, ILLINOIS
From 22-NOV-10 14:15:00 to 22-NOV-10 14:15:00 (CST-6)
Location: KEWANEE MUNI ARPT
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

WGEM-TV reported winds estimated at 70 mph blew a 2 foot diameter tree down 5 miles south of Kewanee.