During the afternoon hours of August 3rd, numerous thunderstorms developed across parts of eastern Missouri and west-central Illinois, triggered by strong surface heating ahead of a surging outflow boundary. These storms developed within a strongly unstable environment, featuring MLCAPE values ranging from 2500 to as much as 4000 J/kg and largely driven by the very warm and humid boundary layer. The initial round of storms struggled to become organized. Eventually cold pool interactions drove upscale growth into a more linear complex. Damaging winds, occasional large hail were reported as well as bursts of very heavy rain rates. By the evening of August 3rd, storms grew upscale, with additional rounds of thunderstorms developing upstream from this initial activity. The primary hazard transitioned from a damaging wind threat to a heavy rain and flash flooding threat, as storms were extremely efficient rain producers. Warm cloud depths were around 4.5km, along with anomalously high precipitable water values of 2 to 2.5 inches, and Corfidi vector orientations that supported westward back-building which enhanced the potential for locally heavy rain, both in terms of instantaneous rates (2+ inches per hour at times) and training of storms. By mid morning on August 4th, widespread rainfall amounts of 1 to 3 inches fell, mainly along and south of I-70 in Missouri and along and east of I-55 in Illinois. Over the St. Louis metro area, as well as Fredericktown, MO, between 4 and 7 inches of rain fell. There were numerous reports of flash flooding in these areas.

Thunderstorm Wind in JERSEY, ILLINOIS
From 03-AUG-22 15:25:00 to 03-AUG-22 15:25:00 (CST-6)
Location: NEWBERN
Magnitude: 61.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm winds blew down several large trees.

Thunderstorm Wind in MADISON, ILLINOIS
From 03-AUG-22 14:32:00 to 03-AUG-22 14:35:00 (CST-6)
Location: ALTON
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Thunderstorm winds blew down several trees near the intersection of 4th Street and Henry Street. Also a large tree was blown over into the front yard, narrowly missing the house. Numerous tree limbs and power lines were blown down around town, including in Oakwood Cemetery.

Thunderstorm Wind in ST. CLAIR, ILLINOIS
From 03-AUG-22 16:40:00 to 03-AUG-22 16:40:00 (CST-6)
Location: (BLV)SCOTT AFB BELLE
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Thunderstorm Wind in CLINTON, ILLINOIS
From 03-AUG-22 17:02:00 to 03-AUG-22 17:10:00 (CST-6)
Location: NEW BADEN
Magnitude: 56.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm winds snapped off a large tree at the ground in New Baden. In Aviston, numerous tree limbs were blown down. Also, the tin roof of an outhouse was ripped off.

Thunderstorm Wind in MADISON, ILLINOIS
From 03-AUG-22 15:55:00 to 03-AUG-22 16:23:00 (CST-6)
Location: MARYLAND PLACE
Magnitude: 61.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm winds caused widespread damage between Granite City, Pontoon Beach, Glen Carbon and Troy. Numerous tree limbs were blown down as well as power lines. Also, several large trees were blown down. In Glen Carbon, some of the fallen trees blocked roads in the Oakdale Lake Drive area. Just east southeast of Troy a large tree fell onto a driveway.

Thunderstorm Wind in MONTGOMERY, ILLINOIS
From 03-AUG-22 14:24:00 to 03-AUG-22 14:30:00 (CST-6)
Location: WHITE OAK
Magnitude: 61.00 EG
Property damage: 12.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm winds blew a road sign over near the north bound lanes of I-55 about 4 miles north of Farmersville. Also, a semi was blown over on I-55 just north of Farmersville. No injuries were reported.

Flash Flood in MONROE, ILLINOIS
From 03-AUG-22 23:21:00 to 04-AUG-22 01:30:00 (CST-6)
Location: BIXBY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Up to 3.5 inches of rain fell in a short amount of time across the northern portions of Monroe County causing flash flooding. Numerous roads were flooded.

Thunderstorm Wind in MONTGOMERY, ILLINOIS
From 03-AUG-22 15:53:00 to 03-AUG-22 15:56:00 (CST-6)
Location: LITCHFIELD MUNI ARPT
Magnitude: 66.00 MG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: AWOS

Thunderstorm winds blew down several power lines around town as well as numerous large tree limbs.

Flash Flood in CLINTON, ILLINOIS
From 04-AUG-22 00:53:00 to 04-AUG-22 03:00:00 (CST-6)
Location: BARTELSO
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Up to 3.5 inches of rain fell in a short amount of time over the eastern half of Clinton County. Several roads were flooded including Old Highway 50 just west of Carlyle. Some homes in Carlyle have basement flooding and water surrounding the homes. Cranford Road was flooded about 2 miles south of Boulder.