June 21st began with widespread stratus and fog across much of northeast Illinois which would give way to breaks of sunshine by late morning. The warming combined with the muggy near-surface conditions led to quick destabilization.  An MCV traversed east overriding the forecast area during peak heating.  This served as an impetus for thunderstorms across northern Illinois, as well as leading to stronger deep layer shear.  Some of these storms developed bowing segments producing strong winds, and numerous thunderstorms were very efficient rain producers due to high moisture content in the atmosphere.  Two of the storms during the span of the event, one across Lake County, IL and the other Iroquois County, were well-defined supercells, each exhibiting deep rotation and for periods low-level rotation.  While no tornadoes were confirmed with these storms, they did bring damaging winds that downed trees as well as caused structural damage in Iroquois County.

Flood in KANE, ILLINOIS
From 21-JUN-14 17:45:00 to 21-JUN-14 22:00:00 (CST-6)
Location: FOX RIVER ESTATES
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Approximately 8 to 10 inches of standing water was reported along Surrey Road.  A CoCoRaHS observer near Sugar Grove measured 2.22 inches of rain in 35 minutes.

Thunderstorm Wind in KANKAKEE, ILLINOIS
From 21-JUN-14 18:00:00 to 21-JUN-14 18:02:00 (CST-6)
Location: GRANT PARK
Magnitude: 60.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Multiple large trees were blown down along area county roads, including one that fell onto a house at 620W County Line Road, and another that was uprooted and fell onto a car.  Some of the trees were up to 16 inches in diameter.

Flood in WILL, ILLINOIS
From 21-JUN-14 17:45:00 to 21-JUN-14 23:30:00 (CST-6)
Location: JOLIET
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

About a foot of standing water was reported on Center Street just north of I-80.  Viaducts in the area had about 8 to 10 inches of water.  A CoCoRaHS observer near Plainfield measured 1.30 inches of rain in 30 minutes.

Thunderstorm Wind in LAKE, ILLINOIS
From 21-JUN-14 15:37:00 to 21-JUN-14 15:37:00 (CST-6)
Location: VOLO
Magnitude: 60.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Amateur Radio

A gazebo was lifted from a backyard and dropped into the front yard onto a gas regulator on Gilmer Road just south of Route 120.

Flood in COOK, ILLINOIS
From 21-JUN-14 17:16:00 to 21-JUN-14 22:30:00 (CST-6)
Location: AVONDALE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The intersection at Argyle Street and Albany Avenue was flooded with six inches of water.

Flash Flood in COOK, ILLINOIS
From 21-JUN-14 17:57:00 to 21-JUN-14 22:30:00 (CST-6)
Location: PARK FOREST
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Around six inches of flowing water was reported on downtown streets of Park Forest.

Thunderstorm Wind in KANKAKEE, ILLINOIS
From 21-JUN-14 14:48:00 to 21-JUN-14 14:48:00 (CST-6)
Location: HERSCHER
Magnitude: 60.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A large tree was blown down onto power lines approximately a block south of Route 115 on Main Street.  A few utility poles and numerous small branches were blown down throughout the village.

Hail in LEE, ILLINOIS
From 21-JUN-14 15:08:00 to 21-JUN-14 15:10:00 (CST-6)
Location: HARMON
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in IROQUOIS, ILLINOIS
From 21-JUN-14 15:20:00 to 21-JUN-14 15:20:00 (CST-6)
Location: CLIFTON
Magnitude: 60.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous trees, power lines and utility lines were blown down across town.  A shed was destroyed approximately two miles south of town.

Thunderstorm Wind in LAKE, ILLINOIS
From 21-JUN-14 15:47:00 to 21-JUN-14 15:47:00 (CST-6)
Location: FAIRFIELD
Magnitude: 61.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in IROQUOIS, ILLINOIS
From 21-JUN-14 15:50:00 to 21-JUN-14 15:50:00 (CST-6)
Location: CRESCENT CITY
Magnitude: 60.00 EG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Public

Numerous trees and power poles were blown down along Route 24.  A warehouse received extensive damage on one end and a farm building also was slightly damaged.

Thunderstorm Wind in LAKE, ILLINOIS
From 21-JUN-14 15:50:00 to 21-JUN-14 15:50:00 (CST-6)
Location: MUNDELEIN
Magnitude: 65.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in LAKE, ILLINOIS
From 21-JUN-14 15:50:00 to 21-JUN-14 15:50:00 (CST-6)
Location: FAIRFIELD
Magnitude: 60.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A tree was blown down and split the roof of a house near Pheasant Run just north of Fairfield Road.

Flash Flood in WILL, ILLINOIS
From 21-JUN-14 17:57:00 to 21-JUN-14 23:30:00 (CST-6)
Location: EAGLE LAKE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Approximately a foot of flowing water was reported over Offner Road.

Thunderstorm Wind in WILL, ILLINOIS
From 21-JUN-14 17:57:00 to 21-JUN-14 17:57:00 (CST-6)
Location: EAGLE LAKE
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Two trees, one 20 inches in diameter and the other 10 inches in diameter, were blown down.  Numerous tree limbs were blown down.

Flood in KANE, ILLINOIS
From 21-JUN-14 18:45:00 to 21-JUN-14 22:00:00 (CST-6)
Location: SUGAR GROVE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Approximately eight inches of standing water was reported over the intersection of Galena Boulevard and Municipal Drive.

Thunderstorm Wind in LAKE, ILLINOIS
From 21-JUN-14 15:30:00 to 21-JUN-14 15:30:00 (CST-6)
Location: ROUND LAKE BEACH
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A number of trees were blown down on the western edge of Round Lake Beach.

Hail in IROQUOIS, ILLINOIS
From 21-JUN-14 15:45:00 to 21-JUN-14 15:50:00 (CST-6)
Location: CRESCENT CITY
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 10.00K
Reported by: Public

Extensive crop damage was reported near Crescent City.

Flash Flood in COOK, ILLINOIS
From 21-JUN-14 16:53:00 to 21-JUN-14 22:30:00 (CST-6)
Location: SKOKIE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Up to six inches of flowing water was reported at Prospect Avenue and Harrison Street.  A CoCoRaHS observer near Winnetka measured 2.19 inches of rain in 55 minutes while the ASOS at O'Hare measured 0.90 inches of rain in 20 minutes.

Flood in KANKAKEE, ILLINOIS
From 21-JUN-14 19:07:00 to 21-JUN-14 23:30:00 (CST-6)
Location: PUDER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Up to four inches of flowing water was reported over portions of 9000N east of Route 1.