During the afternoon, multi-cell thunderstorm clusters developed along a warm front that was oriented from west to east along the Interstate 64 corridor. Surface dew points near and south of the front were in the lower 70's, which contributed to strong instability. Thunderstorm clusters moved eastward along the warm front, but they also developed southward into the strongest instability. Moderately strong deep-layer wind shear resulted in organized clusters of multi-cells with large hail and isolated wind damage. Flash flooding of streets was also reported in a few cities. A secondary line of storms arrived late in the evening and then crossed much of southern Illinois overnight. This line included a bowing line segment that produced isolated wind damage. The secondary line produced flash flooding due to saturated ground from the first round of storms.

Hail in SALINE, ILLINOIS
From 11-MAY-16 18:55:00 to 11-MAY-16 18:55:00 (CST-6)
Location: HARRISBURG
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm Wind in JEFFERSON, ILLINOIS
From 11-MAY-16 14:45:00 to 11-MAY-16 14:45:00 (CST-6)
Location: WALTONVILLE
Magnitude: 52.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Objects were blown off porches.

Thunderstorm Wind in WABASH, ILLINOIS
From 11-MAY-16 15:57:00 to 11-MAY-16 15:57:00 (CST-6)
Location: MT CARMEL
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency management personnel estimated winds gusted from 65 to 70 mph on Route 15.

Thunderstorm Wind in WHITE, ILLINOIS
From 11-MAY-16 15:40:00 to 11-MAY-16 15:40:00 (CST-6)
Location: CROSSVILLE
Magnitude: 56.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Some roof shingles were torn off. A trained spotter estimated winds gusted to 65 mph.

Thunderstorm Wind in JACKSON, ILLINOIS
From 11-MAY-16 22:16:00 to 11-MAY-16 22:16:00 (CST-6)
Location: CARBONDALE
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Several large tree limbs were blown down in the southwest part of the city.

Thunderstorm Wind in HAMILTON, ILLINOIS
From 11-MAY-16 15:18:00 to 11-MAY-16 15:18:00 (CST-6)
Location: DAHLGREN
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Department of Highways

Two trees were blown down on roads in the Dahlgren area.

Hail in FRANKLIN, ILLINOIS
From 11-MAY-16 17:48:00 to 11-MAY-16 17:48:00 (CST-6)
Location: CHRISTOPHER
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in WAYNE, ILLINOIS
From 11-MAY-16 15:15:00 to 11-MAY-16 15:15:00 (CST-6)
Location: MT ERIE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Small tree limbs were also down.

Hail in JEFFERSON, ILLINOIS
From 11-MAY-16 15:24:00 to 11-MAY-16 15:32:00 (CST-6)
Location: SCHELLER
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Tornado in FRANKLIN, ILLINOIS
From 11-MAY-16 17:34:00 to 11-MAY-16 17:34:00 (CST-6)
Location: CLEBURNE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported a very brief tornado. The rural area where this occurred was just east of Illinois 148 and a few miles west-northwest of Orient. No damage was found.

Flash Flood in FRANKLIN, ILLINOIS
From 11-MAY-16 18:25:00 to 11-MAY-16 20:00:00 (CST-6)
Location: FRANKFORT HGTS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Significant street flooding occurred. Water reached the height of a car bumper on a residential side street in West Frankfort. Flash flooding was reported one-half mile east of Benton on Highway 34. A trained spotter in Mulkeytown measured 1.5 to 1.75 inches of rain in 30 minutes.

Flash Flood in WILLIAMSON, ILLINOIS
From 11-MAY-16 18:40:00 to 11-MAY-16 20:00:00 (CST-6)
Location: TIMMONS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous streets were flooded in the eastern part of Marion. A trained spotter measured one to two inches of rain in an hour.

Hail in WAYNE, ILLINOIS
From 11-MAY-16 14:15:00 to 11-MAY-16 14:29:00 (CST-6)
Location: WAYNE CITY
Magnitude: 1.50 
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A slow-moving severe thunderstorm moved into western Wayne County, dumping quarter to ping-pong ball size hail between Wayne City and Orchardville.

Hail in WAYNE, ILLINOIS
From 11-MAY-16 14:26:00 to 11-MAY-16 14:41:00 (CST-6)
Location: FAIRFIELD
Magnitude: 1.75 
Property damage: 80.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A slow-moving severe thunderstorm crossed the city of Fairfield, producing a swath of quarter to golf-ball size hail across the city.

Hail in WABASH, ILLINOIS
From 11-MAY-16 15:12:00 to 11-MAY-16 15:12:00 (CST-6)
Location: COWLING
Magnitude: 1.75 
Crop damage: 0.00K
Reported by: Emergency Manager

Golf-ball size hail was reported along the White County line, about a mile east of Grayville.

Hail in FRANKLIN, ILLINOIS
From 11-MAY-16 16:15:00 to 11-MAY-16 16:15:00 (CST-6)
Location: CHRISTOPHER
Magnitude: 1.50 
Property damage: 40.00K
Crop damage: 0.00K
Reported by: Trained Spotter

These ping-pong ball size hailstones were photographed.

Hail in PERRY, ILLINOIS
From 11-MAY-16 16:18:00 to 11-MAY-16 16:18:00 (CST-6)
Location: DU QUOIN
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flash Flood in PERRY, ILLINOIS
From 11-MAY-16 21:38:00 to 11-MAY-16 23:45:00 (CST-6)
Location: PINCKNEYVILLE
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Water was over Highway 127 south of Pinckneyville. One car was stalled. West of Pinckneyville, two cars were stalled due to flooding on Highway 154. Water was over a few other roads in the city.

Flash Flood in WHITE, ILLINOIS
From 11-MAY-16 22:35:00 to 12-MAY-16 01:15:00 (CST-6)
Location: MIDDLEPOINT
Flood cause: Heavy Rain
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Widespread street flooding was reported across Norris City. In Carmi, several roads were flooded. Water was over other roads in the county, including the intersection of Illinois Route 1 and U.S. 45 near Norris City. Water was over Illinois Route 14 about three miles west of Carmi and over U.S. 45 near Highway 18. A motorist in a stalled car near the Hamilton County line required assistance.

Hail in PERRY, ILLINOIS
From 11-MAY-16 17:24:00 to 11-MAY-16 17:24:00 (CST-6)
Location: DU QUOIN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in FRANKLIN, ILLINOIS
From 11-MAY-16 18:01:00 to 11-MAY-16 18:01:00 (CST-6)
Location: BENTON
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in JACKSON, ILLINOIS
From 11-MAY-16 18:04:00 to 11-MAY-16 18:08:00 (CST-6)
Location: MURPHYSBORO
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WILLIAMSON, ILLINOIS
From 11-MAY-16 18:09:00 to 11-MAY-16 18:09:00 (CST-6)
Location: MARION
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in GALLATIN, ILLINOIS
From 11-MAY-16 18:26:00 to 11-MAY-16 18:26:00 (CST-6)
Location: EQUALITY
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in WILLIAMSON, ILLINOIS
From 11-MAY-16 18:29:00 to 11-MAY-16 18:29:00 (CST-6)
Location: MARION
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in POPE, ILLINOIS
From 11-MAY-16 18:48:00 to 11-MAY-16 18:48:00 (CST-6)
Location: EDDYVILLE
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter