A powerful complex of thunderstorms, known as a bow echo, moved across Missouri and Illinois during the late evening hours of June 26th and early morning hours of June 27th. The line, which raced east at 60 to 70 mph, produced widespread winds of 40 to 60 mph along and north of Interstate 70.  Storm assessment teams from the National Weather Service in St. Louis evaluated the most intense damage which occurred over northeast Missouri and west central Illinois.  From the extreme damage that occurred in localized areas, it appears that wind speeds reached 70 to 100 mph. The extensive nature of the damage caused power outages to at least 55,000 customers. Some did not have power return until Tuesday night.  Also, there were several reports of flash flooding, especially over northeastern Missouri due to the already saturated soils from previous rains over the past week.

Thunderstorm Wind in JERSEY, ILLINOIS
From 27-JUN-11 01:30:00 to 27-JUN-11 01:30:00 (CST-6)
Location: JERSEYVILLE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm winds blew down several power poles onto U.S. Highway 67 south of Jerseyville near Crystal Lake Road.

Thunderstorm Wind in ADAMS, ILLINOIS
From 27-JUN-11 00:30:00 to 27-JUN-11 00:30:00 (CST-6)
Location: MENDON
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

An intense bow echo moved through the area, several large trees and a couple of power lines were blown down just southwest of Mendon.

Thunderstorm Wind in MADISON, ILLINOIS
From 27-JUN-11 01:40:00 to 27-JUN-11 01:40:00 (CST-6)
Location: ALTON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm winds blew down several power lines in town.

Hail in MADISON, ILLINOIS
From 27-JUN-11 01:55:00 to 27-JUN-11 01:55:00 (CST-6)
Location: EDWARDSVILLE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in ADAMS, ILLINOIS
From 27-JUN-11 00:35:00 to 27-JUN-11 00:35:00 (CST-6)
Location: (UIN)QUINCY MUNI ARP
Magnitude: 66.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in ADAMS, ILLINOIS
From 27-JUN-11 00:35:00 to 27-JUN-11 00:45:00 (CST-6)
Location: COATSBURG
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

An intense bow echo moved through Coatsburg, Camp Point and Clayton.  Hundreds of trees, tree limbs and power lines were blown down.  A couple of power poles were also snapped off.  Several trees and tree limbs landed on homes causing minor to moderate roof damage.  Also, in Camp Point the entire roof of a business was blown off.  One woman was injured after falling down her basement steps as her family was taking shelter from the storm.  It took more than an hour for an ambulance to respond to the woman's home near Coatsburg because of the downed trees blocking highways and lots of secondary roads.

Hail in ADAMS, ILLINOIS
From 26-JUN-11 20:33:00 to 26-JUN-11 20:33:00 (CST-6)
Location: LIMA
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in ADAMS, ILLINOIS
From 27-JUN-11 00:30:00 to 27-JUN-11 00:30:00 (CST-6)
Location: LORAINE
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

An intense bow echo moved through blown down several trees, tree limbs and power lines in Loraine.

Thunderstorm Wind in ADAMS, ILLINOIS
From 27-JUN-11 00:40:00 to 27-JUN-11 00:40:00 (CST-6)
Location: LIBERTY
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

An intense bow echo moved through the Liberty area.  A barn lost part of its roof due to the thunderstorm winds.

Thunderstorm Wind in BROWN, ILLINOIS
From 27-JUN-11 00:50:00 to 27-JUN-11 01:00:00 (CST-6)
Location: TIMEWELL
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

An intense bow echo moved through Brown County.  Numerous trees, tree limbs and power lines were blown down.  Many were blocking roads.

Thunderstorm Wind in PIKE, ILLINOIS
From 27-JUN-11 00:50:00 to 27-JUN-11 00:50:00 (CST-6)
Location: BAYLIS
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

An intense bow echo moved through Baylis.  Thunderstorm winds blew down several trees, tree limbs and power lines.  Also, the winds caused a large dent in a 55,000 bushel grain bin.

Thunderstorm Wind in ADAMS, ILLINOIS
From 27-JUN-11 00:30:00 to 27-JUN-11 00:32:00 (CST-6)
Location: QUINCY
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

An intense bow echo moved through Quincy blowing down hundreds of trees, tree limbs and power lines.  The fallen trees, tree limbs and power lines blocked a lot of streets in town causing major navigation issues for drivers for several days.  It also took several days to restore power throughout town. Numerous trees fell onto homes causing varying degrees of damage.  Also, several vehicles sustained varying degrees of damage from fallen trees and limbs.  Amazingly no injuries were reported.

Thunderstorm Wind in ADAMS, ILLINOIS
From 27-JUN-11 00:33:00 to 27-JUN-11 00:35:00 (CST-6)
Location: PAYSON
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

An intense bow echo moved through the Payson area knocking down numerous large trees, tree limbs and power lines.  Some of the fallen trees and tree limbs caused varying degrees of damage to several homes in the area.  Also, part of the roof of a house in the Briarwood Subdivision was blown off.

Thunderstorm Wind in PIKE, ILLINOIS
From 27-JUN-11 01:00:00 to 27-JUN-11 01:05:00 (CST-6)
Location: PERRY
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

An intense bow echo moved through the Perry and Griggsville area.  Numerous trees, tree limbs and power lines were blown down.  In Perry, a large pecan tree was uprooted and fell onto a house causing extensive damage.  Also, when the tree fell over the roots broke a gas line causing a leak.  No injuries were reported.