EF1 tornado, Byars, Oklahoma, April 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 mphthis tornado

   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

EF1

Date

April 22, 2011

Touchdown

7:59 PM CDT (00:59 UTC)

Path length

0.2 miles (0.3 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

Property damage

$5,000

Counties

McClain, Saint Louis, City of Saint Louis and Madison counties

Touchdown point

34.870, -97.032

Lift-off point

34.870, -97.032

Record number

1104221859-01

A cold front moved slowly southeast before stalling near the I-44 corridor. A dry line stretched just ahead of the front, lying from near Lawton southward into northern Texas, with warm, moist air present ahead of it. By early evening, thunderstorms had developed ahead of these boundaries, just south and east of the Oklahoma City metro area. Large hail was reported with several of the thunderstorms. The development of the low-level jet added to the already sufficient wind shear for supercell thunderstorms, but also aided the low-level rotation in some of the thunderstorms. A couple of short-lived tornadoes were reported over Garvin and McClain counties, with some damage reported. The storms continued to develop through the evening hours, with many of them moving over the same areas. The drought that was in place was helped by the welcome rainfall, although a few areas reported brief flash-flooding.

Numerous storm chasers observed a tornado just to the west-southwest of Byars. However, no known damage was reported with this tornado.

Numerous chasers observed a tornado near state highway 59 to the east of Byars. An outbuilding was damaged by this tornado. Several trees were downed. A downed power line caused the town to be without power for several hours. Monetary damages were estimated.

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 00:45 UTC, 14 minutes before the tornado touched down, in force until 01:30 UTC.

The county was under a tornado watch, issued at 20:47 UTC and running to 02:50 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.

Pauls Valley Municipal Airport (PVJ), 25 km from the path, in the two hours either side.

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

The Norman radar (KTLX), 56 km away, was scanning. The volume nearest the touchdown began at 01:00 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

19 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.