EF2 tornado, Cleora to Grove Arpt, Oklahoma, May 22, 2011

1. EF065 to 85 mph

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mphthis tornado

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF2

Date

May 22, 2011

Touchdown

6:33 PM CDT (23:33 UTC)

Lifted

6:48 PM CDT (23:48 UTC)

On the ground

15 minutes

Path length

6.7 miles (10.8 km)

Path width

800 yards (732 m)

Deaths

0

Injuries

0

Property damage

$1.0 million

County

Delaware County

Touchdown point

36.553, -94.973

Lift-off point

36.550, -94.855

Record number

1105221733-01

22 damage points were recorded along this path by NWS TSA, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF3. The highest wind the damage implies is 140 mph.

• Numerous trees were snapped or uprooted in this area. Numerous power poles were also snapped in this area.
• A double wide mobile home was completely destroyed. The mangled frame was found more than 200 yards away. Nearby barns were destroyed and nearby trees were partially debarked. Debris from the mobile home and barns were reduced to small fragments.
• Many large trees were snapped in this area and a number of them were partially debarked.
• A double wide manufactured home was completely destroyed with debris reduced to small fragments. Nearby large hardwood trees were snapped and partially debarked.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

A very moist and very unstable air mass developed across eastern Oklahoma on the afternoon and evening of the 22nd as a dry line moved into the area from the west. Severe thunderstorms, including supercells, developed ahead of the dry line and moved across the area producing tornadoes, large hail up to softball size, and damaging wind gusts.

A tornado severely damaged several permanent homes, destroyed boat docks, damaged a number of other permanent homes, destroyed at least seven mobile homes, and snapped or uprooted many large trees. Maximum estimated wind in the tornado based on this damage was about 130 mph. ||The tornado developed south of Cleora and moved almost due east over land. It then moved across a portion of Grand Lake and back over land north of Dennis, where it appeared to move sharply to the southeast across the northern portion of a peninsula. It likely then moved back over Grand Lake where it dissipated. Storm chasers, storm spotters, and a number of citizens witnessed this tornado.

This is the first of two segments of this tornado. The tornado developed about 2.5 miles west-southwest of Zena, moved east-northeast across Grand Lake and then south of Zena crossing Highway 59 just north of the intersection with Highway 127. Permanent homes were damaged, barns and outbuildings were destroyed, mobile homes were severely damaged, and large trees were snapped or uprooted. The intensity and width of the tornado increased east of Highway 59 where several permanent homes were severely damaged, two double wide mobile homes were destroyed with only small pieces of debris remaining hundreds of yards from the homesite, and many large trees were snapped or uprooted. This extent of damage continued to the state line where a permanent home was severely damaged, two mobile homes were destroyed, and a steel-framed building was destroyed. Two people were injured in the permanent home. Maximum estimated wind in the tornado based on this damage was about 140 mph. The tornado continued into McDonald County, Missouri for about another mile before dissipating.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

9 minutes of warning. NWS TSA issued a tornado warning for this county at 23:24 UTC, 9 minutes before the tornado touched down, in force until 00:00 UTC.

The county was under a tornado watch, issued at 18:27 UTC and running to 01:47 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Moderate Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 20:00 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Grove Municipal Airport (GMJ), 17 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The Tulsa radar (KINX), 72 km away, was scanning. The volume nearest the touchdown began at 23:31 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2011 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

47 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.