National Weather Service Weather Forecast Office

 Information on this webpage is considered preliminary and will continue to be updated as the event is analyzed.

Anyone with information that could enhance the record of these storms should contact the National Weather Service Office in Tulsa at 918-838-7838 during business hours, submit an online storm report, or send us an email at: sr-tsa.stormreport@noaa.gov. Information can also be posted on our Facebook page.

 

Event Summary - 24 May 2011 Tornado and Severe Weather Event - updated 7:00 pm 5/27/11

A significant and deadly tornado outbreak occurred on May 24th as a powerful upper-level storm system moved into the central plains. As a dryline moved east into western Oklahoma, the atmosphere became extremely unstable by late afternoon. Mean layer CAPE values of 3000-4000 J/KG, coupled with very strong 60 to 70 knot deep layer shear and storm relative helicity values in excess of 300 m2/s2 indicated a high potential for supercells capable of producing violent long track tornadoes.

Severe thunderstorms rapidly developed along the dryline in western and central Oklahoma during the afternoon of the 24th and moved east into eastern Oklahoma by early evening. Large tornadoes occurred with the initial supercells in central Oklahoma, then continued into eastern Oklahoma and west central Arkansas overnight, with numerous reports of tornadoes. Damaging straight-line winds also occurred with some of the stronger bow segments with several Oklahoma Mesonet sites measuring wind speeds in excess of 65 mph. NWS Tulsa survey teams continue to assess the damage, and information will be updated on this website as it becomes available. Preliminary Local Storm Reports can be found on the map below.

Survey teams have confirmed that tornadoes occurred in Denning, AR/southeast Franklin County, in Dora, AR/southwest Crawford County, near Haskell/northwest Muskogee County, in Wagoner/Wagoner County, near Pawhuska/Osage County, and in central Le Flore County near Heavener and Howe.  Additional areas of damage will be investigated as more information and reports become available.

 

Preliminary Tornado Information (last updated 7:00 pm 5/27/11):

Denning Tornado (Franklin County Arkansas)

Began: approx. 1.8 miles south of Branch (time to be determined)           Ended: 3.2 miles east of Altus (moved into Johnson County)

Path Length: 18.5 miles in Franklin/Logan counties then moved into Johnson County         Max Path Width: 1.25 miles

EF Rating: EF4 with maximum wind speeds of about 170 mph.

The tornado touched down 1.8 miles south of Branch, AR and traveled northeast through Etna and Denning and into Johnson County.  All of the dimensions of the track have yet to be determined, but it was about 1.25 miles wide at times from north of Highway 288 to near Denning.  The EF4 rating was based on damage that occurred in and around Etna (located about 1 mile north of the intersection of Highways 288 and 23). Several well-built, wood-framed homes were severely damaged, one down to the foundation. The  damaged sustained to a well-built, steel framed home between Etna and the Arkansas River was also considered to be low-end EF4. Some trees were debarked in the Etna area and the ground was considerably scoured by the debris generated by the tornado. The damage that occurred in Denning was rated as EF2. This tornado killed one person in Etna and severely injured several others and killed another person southwest of Denning. Both of these victims were in mobile homes. 

 

Dora Tornado (Sequoyah County Oklahoma/Crawford County Arkansas)

Began: approx. 3.4 miles east-northeast of Roland           Ended: 1.5 miles southwest of Rena

Path Length: 5.25 miles         Max Path Width: 800 yards

EF Rating: EF1 (max wind speed about 105 mph)

Damage:  This tornado destroyed a barn, damaged homes, removed a lot of the siding of a metal building, and snapped or uprooted a number of trees.

 

Haskell Tornado (Muskogee County Oklahoma)

Began: approx. 2 miles southwest of Haskell           Ended: 1 mile southwest of Redbird

Path Length: 8 miles         Max Path Width: 600 yards

EF Rating: EF2 (max wind speed about 125 mph)

Damage: Destroyed a mobile home. Overturned tractor trailer rigs. Snapped power poles.

 

Wagoner Tornado (Wagoner County Oklahoma)

Began: 1.3 miles south-southwest of Wagoner           Ended: 4 miles east of Wagoner

Path Length: 4.4 miles          Max Path Width: 450 yards

EF Rating: EF2 (max wind speed about 115 mph)

Damage: At least one mobile home was destroyed, several other mobile homes and permanent homes were damaged, numerous recreational vehicles were damaged or destroyed, and numerous trees were snapped or uprooted. 

 

Pawhuska Tornado (Osage County Oklahoma)

Began: 10.6 miles northwest of Hominy           Ended: 4.7 miles west-northwest of Pawhuska

Path Length: 17 miles          Max Path Width: 750 yards

EF Rating: EF2 (max wind speed about 115 mph)

Damage: Extensive tree damage, to mostly black oak trees, occurred as well as a number of power poles were snapped.

 

Hominy area Tornado (Osage County Oklahoma)

Began: 10 miles west of Hominy           Ended: 9 miles west-northwest of Hominy

Path Length: 2.8 miles          Max Path Width: 440 yards

EF Rating: EF1 (max wind speed about 95 mph)

Damage: Trees were uprooted and power lines were blown down.

 

Heavener/Howe Tornado (Le Flore County Oklahoma)

Began: 5.3 miles west of Hodgen           Ended: 2.2 miles northeast of Howe

Path Length: 12 miles          Max Path Width: 1 mile

EF Rating: EF2 (max wind speed around 115 mph)

Damage: A mobile home was destroyed, permanent homes were damaged, and trees were snapped or uprooted. Large wooden power poles were also snapped.

 

Information from this event is still considered preliminary and will be modified based on additional information that may become available to us.  Anyone with information that could enhance the record of this event should contact the National Weather Service Office in Tulsa at 918-838-7838 during business hours, or send us an email at sr-tsa.stormreport@noaa.gov, or submit an online report.

 Image captions below the image.  Click on image to open a larger version in a new window.

KSRX radar reflectivity and storm relative velocity showing very strong rotation as a damaging tornado moved through Denning, AR.  Radar image is at 12:11 am CDT 5/25	Animation of Denning tornado from KSRX reflectivity and storm relative velocity.	KINX radar reflectivity and storm relative velocity showing strong rotation as a tornado moved near Haskell, OK.
KINX radar reflectivity and storm relative velocity showing rotation as a tornado moved near Dora, OK.	KINX radar reflectivity and storm relative velocity showing strong rotation as a tornado moved near Pawhuska, OK.	KINX radar reflectivity and storm relative velocity showing rotation as a tornado moved near Wagoner, OK.
Mobile home destroyed by tornado near Haskell, OK.  Residents took shelter in the underground shelter circled in yellow. Photo by NWS Tulsa

 

Preliminary Event Impact Map This map will be updated as additional information is received.  Click on the icons within the map for additional details and/or images related to that impact.  Tornado information can be found by clicking on the track.

Tornado Tracks: Due to mapping/GPS software differences and road accessibility along the track, use the plotted tracks for general reference only. Tornado tracks may be updated and/or changed due to storm damage surveys, data analysis, and eyewitness reports. Storm Survey: Colored icons represent the Storm Survey rating assigned to surveyed damage. Click on the icon for additional information and available photos. You may need to zoom in tightly to see all the available data points when data points are logged close to one another.  Links to photos are available in the upper portion of the text window that opens when you click on one of the colored data icons or points. Hail, Wind, and Flood Reports: Click on the icon for the time, location, and description of the storm report. Click here to submit your storm report. Other Data: Additional data or images from the event.

 

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