Widespread severe thunderstorms, including supercells, occurred over a large area of Oklahoma during the afternoon and evening hours of the 23rd. The thunderstorms were focused near two main boundaries. One was a dry line that was set up over the western third of Oklahoma. The other was a stationary front that was draped over northern Oklahoma. More numerous thunderstorms occurred over northern Oklahoma, with more scattered development to the south. A very unstable air-mass was in place, and a well-timed shortwave was rounding a trough in southwest flow toward Oklahoma and northern Texas. Storms began firing by mid afternoon over northwest Oklahoma, with several supercells developing and merging to the east. A short-lived, weak tornado occurred north of Okeene, but occurred over open terrain with no damage. Other supercell storms developed over western and southwest Oklahoma. Although strong mid-level rotation was present with the southern storms, strong low-level rotation was absent. Very large hail occurred with the storms. One supercell produced a six inch diameter hailstone, the largest in Oklahoma history.  By early evening, many of the thunderstorms persisted, although with less intensity. A boundary left over from the northern Oklahoma storms was draped over central Oklahoma. The development of the low-level jet aided in the development of supercell thunderstorms with large hail. Hail around golf-ball size fell over parts of the Oklahoma City metro area, along with beneficial rainfall. By midnight, the storms had all weakened below severe limits as they moved into eastern Oklahoma.

Hail in WASHITA, OKLAHOMA
From 23-MAY-11 15:33:00 to 23-MAY-11 15:33:00 (CST-6)
Location: ROCKY
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 17:12:00 to 23-MAY-11 17:12:00 (CST-6)
Location: OKARCHE
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 17:13:00 to 23-MAY-11 17:13:00 (CST-6)
Location: OKARCHE
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WASHITA, OKLAHOMA
From 23-MAY-11 15:33:00 to 23-MAY-11 15:33:00 (CST-6)
Location: SENTINEL
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in KIOWA, OKLAHOMA
From 23-MAY-11 16:18:00 to 23-MAY-11 16:18:00 (CST-6)
Location: GOTEBO
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in KIOWA, OKLAHOMA
From 23-MAY-11 16:18:00 to 23-MAY-11 16:18:00 (CST-6)
Location: GOTEBO
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Flash Flood in GARFIELD, OKLAHOMA
From 23-MAY-11 17:40:00 to 23-MAY-11 20:00:00 (CST-6)
Location: LAHOMA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Water was overflowing the streets, making them impassable.

Hail in MAJOR, OKLAHOMA
From 23-MAY-11 15:24:00 to 23-MAY-11 15:24:00 (CST-6)
Location: RINGWOOD
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

The report was relayed by an off-duty WFO Hastings, Nebraska Employee.

Hail in LOGAN, OKLAHOMA
From 23-MAY-11 18:23:00 to 23-MAY-11 18:23:00 (CST-6)
Location: CRESCENT
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in BLAINE, OKLAHOMA
From 23-MAY-11 18:30:00 to 23-MAY-11 18:30:00 (CST-6)
Location: OKEENE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 20:43:00 to 23-MAY-11 20:43:00 (CST-6)
Location: OKARCHE
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in KINGFISHER, OKLAHOMA
From 23-MAY-11 20:44:00 to 23-MAY-11 20:44:00 (CST-6)
Location: OKARCHE
Magnitude: 3.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in COMANCHE, OKLAHOMA
From 23-MAY-11 17:23:00 to 23-MAY-11 17:23:00 (CST-6)
Location: INDIAHOMA
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in CADDO, OKLAHOMA
From 23-MAY-11 17:10:00 to 23-MAY-11 17:10:00 (CST-6)
Location: CARNEGIE
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in KAY, OKLAHOMA
From 23-MAY-11 15:35:00 to 23-MAY-11 15:35:00 (CST-6)
Location: BRAMAN
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in OKLAHOMA, OKLAHOMA
From 23-MAY-11 20:17:00 to 23-MAY-11 20:17:00 (CST-6)
Location: EDMOND
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in KAY, OKLAHOMA
From 23-MAY-11 15:37:00 to 23-MAY-11 15:37:00 (CST-6)
Location: BRAMAN
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in BLAINE, OKLAHOMA
From 23-MAY-11 18:35:00 to 23-MAY-11 18:35:00 (CST-6)
Location: HITCHCOCK
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in GARFIELD, OKLAHOMA
From 23-MAY-11 16:19:00 to 23-MAY-11 16:19:00 (CST-6)
Location: ENID
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in GRANT, OKLAHOMA
From 23-MAY-11 16:21:00 to 23-MAY-11 16:21:00 (CST-6)
Location: RENFROW
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in KIOWA, OKLAHOMA
From 23-MAY-11 17:32:00 to 23-MAY-11 17:35:00 (CST-6)
Location: GOTEBO
Magnitude: 6.00 
Reported by: NWS Employee

An off-duty NWS meteorologist, working as part of a hail research team reported a six inch diameter hailstone two miles north of Gotebo. The hailstone caused significant damage to one of the team's vehicles. Further investigation and discussion with the Oklahoma State Climatologist confirmed that this hailstone is the largest hailstone on record in Oklahoma.

Hail in MAJOR, OKLAHOMA
From 23-MAY-11 15:24:00 to 23-MAY-11 15:24:00 (CST-6)
Location: RINGWOOD
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in KINGFISHER, OKLAHOMA
From 23-MAY-11 19:09:00 to 23-MAY-11 19:09:00 (CST-6)
Location: KINGFISHER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 20:44:00 to 23-MAY-11 20:44:00 (CST-6)
Location: OKARCHE
Magnitude: 2.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 21:20:00 to 23-MAY-11 21:20:00 (CST-6)
Location: PIEDMONT
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WASHITA, OKLAHOMA
From 23-MAY-11 15:24:00 to 23-MAY-11 15:24:00 (CST-6)
Location: SENTINEL
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CADDO, OKLAHOMA
From 23-MAY-11 17:30:00 to 23-MAY-11 17:30:00 (CST-6)
Location: APACHE
Magnitude: 3.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CADDO, OKLAHOMA
From 23-MAY-11 17:30:00 to 23-MAY-11 17:30:00 (CST-6)
Location: CARNEGIE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in WASHITA, OKLAHOMA
From 23-MAY-11 15:45:00 to 23-MAY-11 15:45:00 (CST-6)
Location: SENTINEL
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in JACKSON, OKLAHOMA
From 23-MAY-11 15:46:00 to 23-MAY-11 15:46:00 (CST-6)
Location: ELMER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in KIOWA, OKLAHOMA
From 23-MAY-11 16:24:00 to 23-MAY-11 16:24:00 (CST-6)
Location: GOTEBO
Magnitude: 3.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in KINGFISHER, OKLAHOMA
From 23-MAY-11 19:17:00 to 23-MAY-11 19:17:00 (CST-6)
Location: KINGFISHER
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in KINGFISHER, OKLAHOMA
From 23-MAY-11 19:22:00 to 23-MAY-11 19:22:00 (CST-6)
Location: KINGFISHER
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in TILLMAN, OKLAHOMA
From 23-MAY-11 16:29:00 to 23-MAY-11 16:29:00 (CST-6)
Location: MANITOU
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 21:27:00 to 23-MAY-11 21:27:00 (CST-6)
Location: PIEDMONT
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Tornado in BLAINE, OKLAHOMA
From 23-MAY-11 15:26:00 to 23-MAY-11 15:28:00 (CST-6)
Location: OKEENE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Off-duty NWS meteorologists, storm chasers, and local broadcast media confirmed a tornado that lasted 1 to 2 minutes. No known damage occurred.

Hail in GARFIELD, OKLAHOMA
From 23-MAY-11 15:54:00 to 23-MAY-11 15:54:00 (CST-6)
Location: ENID
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in OKLAHOMA, OKLAHOMA
From 23-MAY-11 21:31:00 to 23-MAY-11 21:31:00 (CST-6)
Location: THE VILLAGE
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

The hail was reported near NW 164th Street and Meridian Avenue.

Hail in KINGFISHER, OKLAHOMA
From 23-MAY-11 17:31:00 to 23-MAY-11 17:31:00 (CST-6)
Location: OKARCHE
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in CADDO, OKLAHOMA
From 23-MAY-11 17:44:00 to 23-MAY-11 17:44:00 (CST-6)
Location: APACHE
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Thunderstorm Wind in KAY, OKLAHOMA
From 23-MAY-11 16:01:00 to 23-MAY-11 16:01:00 (CST-6)
Location: PONCA CITY
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

No damage occurred with the wind gust.

Hail in TILLMAN, OKLAHOMA
From 23-MAY-11 16:40:00 to 23-MAY-11 16:40:00 (CST-6)
Location: MANITOU
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in KIOWA, OKLAHOMA
From 23-MAY-11 16:45:00 to 23-MAY-11 16:45:00 (CST-6)
Location: MOUNTAIN VIEW
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in KINGFISHER, OKLAHOMA
From 23-MAY-11 19:25:00 to 23-MAY-11 19:25:00 (CST-6)
Location: KINGFISHER
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in KINGFISHER, OKLAHOMA
From 23-MAY-11 19:31:00 to 23-MAY-11 19:31:00 (CST-6)
Location: KINGFISHER
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 21:45:00 to 23-MAY-11 21:45:00 (CST-6)
Location: YUKON
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in MAJOR, OKLAHOMA
From 23-MAY-11 14:49:00 to 23-MAY-11 14:49:00 (CST-6)
Location: FAIRVIEW
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in OKLAHOMA, OKLAHOMA
From 23-MAY-11 21:45:00 to 23-MAY-11 21:45:00 (CST-6)
Location: THE VILLAGE
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

The hail was reported near Western Avenue and Memorial Road.

Hail in KIOWA, OKLAHOMA
From 23-MAY-11 16:35:00 to 23-MAY-11 16:35:00 (CST-6)
Location: GOTEBO
Magnitude: 3.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in CADDO, OKLAHOMA
From 23-MAY-11 17:00:00 to 23-MAY-11 17:00:00 (CST-6)
Location: CARNEGIE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in DEWEY, OKLAHOMA
From 23-MAY-11 14:55:00 to 23-MAY-11 14:55:00 (CST-6)
Location: SEILING
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in MAJOR, OKLAHOMA
From 23-MAY-11 15:29:00 to 23-MAY-11 15:29:00 (CST-6)
Location: RINGWOOD
Magnitude: 3.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

The hail report was relayed by an off-duty NWS Hastings, Nebraska employee.

Hail in TILLMAN, OKLAHOMA
From 23-MAY-11 16:15:00 to 23-MAY-11 16:15:00 (CST-6)
Location: TIPTON
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail in KIOWA, OKLAHOMA
From 23-MAY-11 16:13:00 to 23-MAY-11 16:13:00 (CST-6)
Location: GOTEBO
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in OKLAHOMA, OKLAHOMA
From 23-MAY-11 21:55:00 to 23-MAY-11 21:55:00 (CST-6)
Location: EDMOND
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in MAJOR, OKLAHOMA
From 23-MAY-11 14:55:00 to 23-MAY-11 14:55:00 (CST-6)
Location: FAIRVIEW
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 17:07:00 to 23-MAY-11 17:07:00 (CST-6)
Location: OKARCHE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in MAJOR, OKLAHOMA
From 23-MAY-11 17:58:00 to 23-MAY-11 17:58:00 (CST-6)
Location: FAIRVIEW
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in PAYNE, OKLAHOMA
From 23-MAY-11 19:46:00 to 23-MAY-11 19:46:00 (CST-6)
Location: STILLWATER
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Hail in OKLAHOMA, OKLAHOMA
From 23-MAY-11 21:59:00 to 23-MAY-11 21:59:00 (CST-6)
Location: EDMOND
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The hail was reported near Coltrane Road and Memorial Road.

Hail in KINGFISHER, OKLAHOMA
From 23-MAY-11 17:11:00 to 23-MAY-11 17:11:00 (CST-6)
Location: KINGFISHER
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in LOGAN, OKLAHOMA
From 23-MAY-11 18:07:00 to 23-MAY-11 18:07:00 (CST-6)
Location: MULHALL
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

No damage occurred with the wind gust.

Hail in CANADIAN, OKLAHOMA
From 23-MAY-11 20:40:00 to 23-MAY-11 20:40:00 (CST-6)
Location: OKARCHE
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in OKLAHOMA, OKLAHOMA
From 23-MAY-11 22:00:00 to 23-MAY-11 22:00:00 (CST-6)
Location: FOREST PARK
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

The hail was reported near Exit 136 on Interstate 35, near the Turner Turnpike.

Hail in DEWEY, OKLAHOMA
From 23-MAY-11 15:05:00 to 23-MAY-11 15:05:00 (CST-6)
Location: OAKWOOD
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail in MAJOR, OKLAHOMA
From 23-MAY-11 15:20:00 to 23-MAY-11 15:20:00 (CST-6)
Location: RINGWOOD
Magnitude: 2.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public