EF0 tornado, Wakita, Oklahoma, September 17, 2011

1. EF065 to 85 mphthis tornado

   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 mph

   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

EF0

Date

September 17, 2011

Touchdown

5:55 PM CDT (22:55 UTC)

Path length

0.5 miles (0.8 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

County

Grant County

Touchdown point

36.784, -97.897

Lift-off point

36.784, -97.897

Record number

1109171655-01

A warm front moved slowly north through Oklahoma, settling near the Oklahoma and Kansas border by mid afternoon. Scattered thunderstorms developed over western and northern Oklahoma, with another area of thunderstorms developing near the Red River. The thunderstorms produced large hail and heavy rain as they moved east and northeast. One thunderstorm, however, remained discrete and moved east and then east-southeast over north-central Oklahoma. Backed surface winds near the warm front helped maximize low-level wind shear, and three brief tornadoes developed over open country in Grant county. The storms over southwest Oklahoma weakened with the loss of daytime heating, but the northern Oklahoma storms merged into a complex. This complex continued well into the evening producing heavy rain.

Numerous storm chasers reported a tornado south of Wakita that persisted for a few minutes as it moved southeast. No damage was reported.

A second tornado was observed by numerous storm chasers to the northeast of the larger tornado that was occurring south of Wakita. This tornado was a narrow rope tornado that became very elongated and tilted from the cloud base. No damage was reported with this tornado.

A third brief tornado was observed by a media storm chaser. Again, no damage was reported with this tornado.

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

14 minutes of warning. NWS OUN issued a tornado warning for this county at 22:41 UTC, 14 minutes before the tornado touched down, in force until 23:45 UTC.

The county was under a tornado watch, issued at 19:30 UTC and running to 04:00 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 Slight Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:56 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.

Enid/Woodring Municipal (WDG), 46 km from the path, in the two hours either side.

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

The Vance AFB radar (KVNX), 21 km away, was scanning. The volume nearest the touchdown began at 22:55 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

3 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.