A cluster of severe thunderstorms moved southeast along a warm front as the front lifted north across southern Illinois. Steep mid-level lapse rates were highly favorable for large hail. There were numerous swaths of large hail up to the size of golf balls that accompanied the strongest storms. The cluster of severe thunderstorms moved southeast from the southern suburbs of St. Louis, passing across Rend Lake, Marion, and Harrisburg by mid-afternoon. The complex of storms crossed the Ohio River into western Kentucky late in the afternoon.

Hail in FRANKLIN, ILLINOIS
From 12-MAR-20 13:07:00 to 12-MAR-20 13:08:00 (CST-6)
Location: ROYALTON
Magnitude: 2.00 
Crop damage: 0.00K
Reported by: Public

There were multiple reports of large hail ranging from one to two inches in diameter in the Royalton and Zeigler areas.

Hail in WILLIAMSON, ILLINOIS
From 12-MAR-20 13:12:00 to 12-MAR-20 13:23:00 (CST-6)
Location: HURST
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Quarter-size hail fell in the Hurst and Colp areas.

Hail in WILLIAMSON, ILLINOIS
From 12-MAR-20 13:20:00 to 12-MAR-20 13:22:00 (CST-6)
Location: JOHNSTON CITY
Magnitude: 2.00 
Crop damage: 0.00K
Reported by: Storm Chaser

Traffic was stopped on Interstate 57 outside Johnston City due to wind-driven large hail up to two inches in diameter. The hail was reported to be golf ball size in Johnston City.

Hail in WILLIAMSON, ILLINOIS
From 12-MAR-20 13:24:00 to 12-MAR-20 13:24:00 (CST-6)
Location: MARION
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Numerous reports were received of half-dollar size hail in Marion.

Hail in WILLIAMSON, ILLINOIS
From 12-MAR-20 13:25:00 to 12-MAR-20 13:25:00 (CST-6)
Location: CARTERVILLE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in SALINE, ILLINOIS
From 12-MAR-20 13:44:00 to 12-MAR-20 13:51:00 (CST-6)
Location: MUDDY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

There were multiple reports of quarter-size hail in the Harrisburg area, from just north of town (near Muddy) to just south of town.

Hail in SALINE, ILLINOIS
From 12-MAR-20 13:45:00 to 12-MAR-20 13:45:00 (CST-6)
Location: CARRIERS MILLS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flash Flood in FRANKLIN, ILLINOIS
From 12-MAR-20 13:43:00 to 12-MAR-20 14:45:00 (CST-6)
Location: WEST FRANKFORT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Flooding was reported across parts of the county due to water drainage being impeded by hail on the ground.

Thunderstorm Wind in FRANKLIN, ILLINOIS
From 12-MAR-20 12:49:00 to 12-MAR-20 12:49:00 (CST-6)
Location: BENTON
Magnitude: 65.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A pole barn was destroyed in the city.

Hail in FRANKLIN, ILLINOIS
From 12-MAR-20 13:21:00 to 12-MAR-20 13:21:00 (CST-6)
Location: WEST FRANKFORT
Magnitude: 1.75 
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in FRANKLIN, ILLINOIS
From 12-MAR-20 12:41:00 to 12-MAR-20 12:52:00 (CST-6)
Location: SESSER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A swath of quarter-size hail occurred from Sesser across southern Rend Lake.

Hail in PERRY, ILLINOIS
From 12-MAR-20 12:45:00 to 12-MAR-20 12:53:00 (CST-6)
Location: PYATTS
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A swath of quarter to half dollar size hail fell across southern Perry County, roughly along Route 13 from Du Quoin to the intersection of Route 152.

Hail in JEFFERSON, ILLINOIS
From 12-MAR-20 12:48:00 to 12-MAR-20 12:48:00 (CST-6)
Location: INA
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public