EF0 tornado, Redden to Daisy, Oklahoma, April 14, 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

April 14, 2011

Touchdown

8:04 PM CDT (01:04 UTC)

Lifted

8:11 PM CDT (01:11 UTC)

On the ground

7 minutes

Path length

7.0 miles (11.3 km)

Path width

125 yards (114 m)

Deaths

0

Injuries

0

Counties

Atoka and Pushmataha counties

Touchdown point

34.430, -95.890

Lift-off point

34.450, -95.762

Record number

1104141904-01

An upper level trough moved onshore along the west coast on the 13th, and continued east toward the plains. The storm system strengthened as it moved east of the Rocky mountains, eventually becoming a major storm system, with blizzard conditions on the west and north sides of it, and powerful thunderstorms to the south and east. A surface low pressure moved from the Texas panhandle into southern Kansas, with a dry line extending to the south. The dry line moved quickly east before slowing to the east of I-35 in Oklahoma. Dew point temperatures reached the middle 60s east of the dry line, with bone-dry conditions advecting in on the back side of the dry line. The cap that was in place was all but erased by mid afternoon, and thunderstorms quickly developed over eastern Oklahoma. The wind shear in place was more than sufficient for rotating thunderstorms, with most storms become supercells. Very large hail and wind damage was common early in the thunderstorm life cycle. A weak tornado developed northwest of Stroud, with other storms showing signs of rotation by late afternoon. Additional tornadoes developed through the early evening, with a couple of them doing damage. The tornadoes were in addition to the hail up to softball size. By late evening, at least five tornadoes were reported, with one of them rated and EF-3.

Low pressure was centered over southern Kansas during the early afternoon of the 14th with a sharp dryline extending from the low pressure system through central Oklahoma. A moist and very unstable air mass was in place across eastern Oklahoma ahead of the dryline. Severe thunderstorms developed along the dryline during the afternoon and moved into eastern Oklahoma during the early evening hours. Large hail up to grapefruit size, damaging wind gusts, and numerous tornadoes occurred as the storms moved through the region.

A tornado was observed by a storm chaser that developed south-southwest of Redden and moved east-northeast into Pushmataha County (see Storm Data for eastern Oklahoma for the Pushmataha County portion of this tornado.) This tornado produced no known damage.

This is the second of two segments of this tornado, which developed in Atoka County, Oklahoma. A storm chaser witnessed a large cone-shaped tornado over open country. No known damage resulted from this tornado.

A storm chaser observed a brief tornado northwest of Jumbo that was over open country. This tornado produced no known damage.

A tornado snapped or uprooted a number of trees. Power poles were also snapped by this tornado. Maximum estimated wind in the tornado based on this damage was about 100 mph. This tornado was observed by a storm chaser.

Another area of damage occurred south of the large tornado that devastated Tushka. This tornado damaged numerous trees and power lines. Monetary damages were estimated.

An NWS storm survey found a barn destroyed and numerous large trees snapped or uprooted along a path from northeast of Redden to west-southwest of Daisy. Monetary damages were estimated.

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

70 minutes of warning. NWS OUN issued a tornado warning for this county at 23:54 UTC, 70 minutes before the tornado touched down, in force until 01:15 UTC.

The county was under a tornado watch, issued at 19:28 UTC and running to 02:07 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 0.15 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 00:59 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.

Atoka Municipal Airport (AQR), 30 km from the path, in the two hours either side.

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

The Western Arkansas radar (KSRX), 164 km away, was scanning. The volume nearest the touchdown began at 01:04 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.