Multiple rounds of thunderstorms impacted the region on the last day of May. Damaging winds, large hail, flooding, and a couple tornadoes were observed in this outbreak. The first round of storms moved through southern Illinois, mainly north of Route 13, during the morning hours. Widespread damaging winds were associated with this line of storms. Scattered thunderstorm development then began by mid to late afternoon, with coverage increasing further into the evening hours. The first round of storms left an outflow boundary across southeast Missouri and the lower Ohio Valley, where scattered thunderstorms developed. Surface dewpoints near the boundary were in the lower 70s, which contributed to moderately strong instability. A subtle shortwave trough across the mid Mississippi Valley and lower Missouri Valley provided large-scale ascent for the evening round of storms. Mid-level winds around 50 knots located just ahead of the shortwave helped to create moderate to strong deep-layer wind shear, favorable for a few supercells.

Hail in ALEXANDER, ILLINOIS
From 31-MAY-18 13:53:00 to 31-MAY-18 13:53:00 (CST-6)
Location: CAIRO
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

This hail occurred at the Cairo Fire Department.

Hail in WILLIAMSON, ILLINOIS
From 31-MAY-18 18:20:00 to 31-MAY-18 18:20:00 (CST-6)
Location: CREAL SPGS
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in HAMILTON, ILLINOIS
From 31-MAY-18 18:55:00 to 31-MAY-18 18:55:00 (CST-6)
Location: BROUGHTON
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

This hail was reported near the community of Gossett, off U.S. Highway 45 near the White County line.

Hail in WHITE, ILLINOIS
From 31-MAY-18 19:01:00 to 31-MAY-18 19:04:00 (CST-6)
Location: NORRIS CITY
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Ping pong ball size hail was reported at Norris City. Quarter-size hail fell near the Hamilton County line off U.S. Highway 45 near Gossett.

Hail in PERRY, ILLINOIS
From 31-MAY-18 19:49:00 to 31-MAY-18 19:49:00 (CST-6)
Location: DU QUOIN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in PERRY, ILLINOIS
From 31-MAY-18 20:36:00 to 31-MAY-18 20:36:00 (CST-6)
Location: DU QUOIN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in HAMILTON, ILLINOIS
From 31-MAY-18 09:35:00 to 31-MAY-18 09:35:00 (CST-6)
Location: BELLE PRAIRIE
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A wind gust to 58 mph was measured near Interstate 64.

Flood in SALINE, ILLINOIS
From 31-MAY-18 09:30:00 to 31-MAY-18 10:15:00 (CST-6)
Location: GALATIA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flooding was reported along Highway 34.

Thunderstorm Wind in JACKSON, ILLINOIS
From 31-MAY-18 08:10:00 to 31-MAY-18 08:20:00 (CST-6)
Location: POMONA
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

Numerous large trees were blown down just off U.S. Highway 51 near Makanda. There were reports of downed tree limbs elsewhere in southern parts of the county.

Thunderstorm Wind in JACKSON, ILLINOIS
From 31-MAY-18 08:25:00 to 31-MAY-18 08:40:00 (CST-6)
Location: CAMPBELL HILL
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Trees were down on power lines in the northern parts of the county.

Thunderstorm Wind in PERRY, ILLINOIS
From 31-MAY-18 08:38:00 to 31-MAY-18 08:53:00 (CST-6)
Location: PINCKNEYVILLE
Magnitude: 56.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Multiple trees and power lines were down across the county. Power outages were reported. In Pinckneyville, many tree limbs were down and shingles were blown off a house.

Thunderstorm Wind in FRANKLIN, ILLINOIS
From 31-MAY-18 09:00:00 to 31-MAY-18 09:00:00 (CST-6)
Location: SESSER
Magnitude: 56.00 EG
Property damage: 8.00K
Crop damage: 0.00K
Reported by: Public

Numerous tree limbs were down. Gutters were blown off a house. Power outages occurred across the county.

Thunderstorm Wind in JEFFERSON, ILLINOIS
From 31-MAY-18 09:10:00 to 31-MAY-18 09:15:00 (CST-6)
Location: WOODLAWN
Magnitude: 68.00 MG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Scattered tree damage was reported across the county. Large limbs were down between Woodlawn and Mt. Vernon. Structural damage to outbuildings was reported near Waltonville. A wind gust to 78 mph was measured at the Mt. Vernon airport.

Thunderstorm Wind in SALINE, ILLINOIS
From 31-MAY-18 09:10:00 to 31-MAY-18 09:15:00 (CST-6)
Location: CARRIERS MILLS
Magnitude: 56.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trees and power lines were down across the county, including Galatia and Carrier Mills.

Thunderstorm Wind in HAMILTON, ILLINOIS
From 31-MAY-18 09:30:00 to 31-MAY-18 09:30:00 (CST-6)
Location: DALE
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Trees were blown down, making Route 142 impassable near Dale.

Thunderstorm Wind in WAYNE, ILLINOIS
From 31-MAY-18 09:35:00 to 31-MAY-18 09:50:00 (CST-6)
Location: WAYNE CITY
Magnitude: 56.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency management personnel estimated sustained winds were 40 to 45 mph with gusts above 60 mph. Trees and power lines were down across the county. Generators were being utilized in Fairfield, where the doors were blown open at the health department.

Thunderstorm Wind in WHITE, ILLINOIS
From 31-MAY-18 09:55:00 to 31-MAY-18 09:55:00 (CST-6)
Location: CARMI
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Small trees and power lines were down.

Thunderstorm Wind in EDWARDS, ILLINOIS
From 31-MAY-18 10:02:00 to 31-MAY-18 10:10:00 (CST-6)
Location: ALBION
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: State Official

A couple of small limbs were down in Albion. A large tree was down in Browns.

Thunderstorm Wind in WABASH, ILLINOIS
From 31-MAY-18 10:28:00 to 31-MAY-18 10:28:00 (CST-6)
Location: ALLENDALE
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Public

A tree fell on a house.

Tornado in UNION, ILLINOIS
From 31-MAY-18 18:54:00 to 31-MAY-18 19:02:00 (CST-6)
Location: WOLF LAKE
Tornado F-scale: EF1
Property damage: 70.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A storm survey team estimated peak winds up to 95 mph occurred with this tornado, which touched down along the Mississippi River levee. The tornado passed near the community of Wolf Lake before dissipating at the edge of the Shawnee National Forest just east of Route 3. A very large equipment barn collapsed, and another barn was destroyed. A one-story house was partially shifted off its foundation. All structural damage was between Route 3 and the Mississippi River levee. The tornado was witnessed by at least one trained spotter and several other individuals. Prior to spawning this tornado, the parent storm produced a tornado near Trail of Tears State Park in Cape Girardeau County, Missouri about ten minutes earlier.

Tornado in UNION, ILLINOIS
From 31-MAY-18 18:55:00 to 31-MAY-18 18:59:00 (CST-6)
Location: WOLF LAKE
Tornado F-scale: EF0
Property damage: 7.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Peak winds were estimated by a National Weather Service survey team near 75 mph.  This weak tornado occurred in close proximity to another tornado about a mile north. Several tree limbs were broken. The roof of a barn was blown in on one side. This tornado also occurred near the Mississippi River between Route 3 and the levee. Prior to spawning this tornado, the parent storm produced a tornado near Trail of Tears State Park in Cape Girardeau County, Missouri about ten minutes earlier.