Thunderstorms initiated along an old outflow boundary extending from Jacksonville to near Lawrenceville during the evening of June 17th.  Due to a strong low-level jet flowing into the area, the storms continually re-developed and tracked across the same locations, producing between 5 and 10 inches of rain across parts of Morgan and western Sangamon counties through the morning of June 18th.  As a result, widespread flash flooding occurred from the Jacksonville area eastward to the Sangamon County border.  Significant flash flooding also occurred in a large part of southeast Illinois where 3 to 9 inches of rain was reported. A few of the storms also produced gusty winds and small hail.

Flash Flood in LAWRENCE, ILLINOIS
From 18-JUN-11 02:00:00 to 18-JUN-11 13:00:00 (CST-6)
Location: CHAUNCEY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms produced 4.00 to 6.00 of rain in much of Lawrence County during the early morning hours of June 18th. U.S. Highway 50 was inundated in several locations, streets were flooded in a large part of Lawrenceville, Illinois Routes 33 and 1 were flooded over, and almost all rural roads were impassable due to the high water.

Flash Flood in MORGAN, ILLINOIS
From 17-JUN-11 22:45:00 to 18-JUN-11 21:33:00 (CST-6)
Location: MEREDOSIA
Flood cause: Heavy Rain
Property damage: 150.00M
Crop damage: 0.00K
Reported by: Emergency Manager

Flash flooding of historic proportions occurred in much of Morgan County from late in the evening of June 17th through much of June 18th. Rainfall amounts of 5.00 to 10.00 were reported, with the highest totals in east central Morgan County from Alexander to Franklin.
The nearly stationary thunderstorms produced a majority of the rain between 2200 LST and 0300 LST. The cities of Jacksonville and South Jacksonville recorded nearly 6.00 of rain in less than six hours, which was about 1.00 higher than a 100 year flood for that time period.
Nearly 2,500 homes, more than 100 businesses - including the Nestle Chocolate plant and many restaurants, MacMurrary College, and a state prison with more than 1,600 inmates sustained major flash flood damage. A levee for Mauvaise Terre Lake was overtopped at the Jacksonville Water Treatment Plant, destroying much of the equipment at the facility and shutting off the drinking water supply in Jacksonville for about three weeks until the equipment could be replaced and tested.
Several miles of Interstate 72 east and south of Jacksonville were closed due to high water during the morning of June 18th. Most streets in eastern and southern parts of Jacksonville were covered with several feet of water, and every rural road and highway in the eastern half of the county was water covered and closed.
Numerous people had to be rescued from their vehicles and at the Rolling Acres Mobile Estates mobile home park, however there were no reports of injuries or fatalities. Several pets, however, drowned due to the flooding at the mobile home park.
Property and business damages were estimated to be about $150 Million. There was no estimate available for crop damages in eastern Morgan County. The flash flooding continued as an areal flood for the same areas for at least another 40 hours, but the impacts of the flooding were felt for more than three weeks.

Hail in SANGAMON, ILLINOIS
From 18-JUN-11 06:49:00 to 18-JUN-11 06:50:00 (CST-6)
Location: SPRINGFIELD
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in CLAY, ILLINOIS
From 18-JUN-11 02:41:00 to 18-JUN-11 02:46:00 (CST-6)
Location: INGRAHAM
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A tree was blown down onto Ingraham Road.

Flash Flood in EFFINGHAM, ILLINOIS
From 18-JUN-11 01:50:00 to 18-JUN-11 07:00:00 (CST-6)
Location: BEECHER CITY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorms produced nearly 3.50 of rain in about 90 minutes during the early morning hours of June 18th. Total rainfall amounts ranged from 3.50 to 6.00 across much of the county. Almost all rural roads were impassable, and significant street flooding was reported in the city of Effingham.

Flash Flood in SANGAMON, ILLINOIS
From 17-JUN-11 23:15:00 to 18-JUN-11 21:33:00 (CST-6)
Location: BERLIN
Flood cause: Heavy Rain
Property damage: 3.00M
Crop damage: 10.00M
Reported by: Emergency Manager

Flash flooding of historic proportions occurred in western Sangamon County from late in the evening of June 17th through much of June 18th. Rainfall amounts of 5.00 to 9.00 were reported, with the highest totals along the boder with Morgan County. The nearly stationary thunderstorms produced a majority of the rain between 2200 LST and 0300 LST.
Every rural road and state highway in western Sangamon County was water covered and closed. Streets and about 300 homes in the towns of New Berlin and Loami, as well as numerous farms in west central parts of the county, were severely flooded. Around 22,000 acres of farmland also sustained significant flooding.
Property and business damages were estimated to be about $3 Million, while crop losses could be close to $10 Million. The flash flooding continued as an areal flood for the same areas for at least another 20 hours.

Flash Flood in CUMBERLAND, ILLINOIS
From 18-JUN-11 02:30:00 to 18-JUN-11 06:30:00 (CST-6)
Location: NEOGA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms produced nearly 3.00 to 5.00 of rain in southwest Cumberland County during the early morning hours of June 18th. Almost all rural roads were impassable due to the high water.

Flash Flood in CLAY, ILLINOIS
From 18-JUN-11 02:30:00 to 18-JUN-11 06:30:00 (CST-6)
Location: HORD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms produced 5.00 to 6.00 of rain in northern Clay County during the early morning hours of June 18th. U.S. Highway 45 was inundated, and almost all rural roads were impassable due to the high water.

Flash Flood in JASPER, ILLINOIS
From 18-JUN-11 01:50:00 to 18-JUN-11 13:00:00 (CST-6)
Location: ISLAND GROVE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms produced 4.00 to 8.00 of rain in western Jasper County during the
morning hours of June 18th. State Highways 130 and 33 were inundated, most streets in Newton were flooded, and almost all rural roads were impassable due to the high water.

Flash Flood in RICHLAND, ILLINOIS
From 18-JUN-11 01:50:00 to 18-JUN-11 13:00:00 (CST-6)
Location: WAKEFIELD
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms produced 4.00 to 9.00 of rain in much of Richland County during the early morning hours of June 18th. U.S. Highway 50 was inundated in several locations, streets were flooded in a large part of Olney, and almost all rural roads were impassable due to the high water.

Flash Flood in SHELBY, ILLINOIS
From 18-JUN-11 01:50:00 to 18-JUN-11 07:00:00 (CST-6)
Location: OCONEE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorms produced nearly 3.50 of rain in about 90 minutes during the early morning hours of June 18th. Total rainfall amounts ranged from 4.00 to 6.00 across extreme southern Shelby county. The impacted rural roads were impassable due to the flooding.