EF2 tornado, Gracemont to Anadarko, Oklahoma, May 13, 2009

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 13, 2009

Touchdown

9:26 PM CDT (02:26 UTC)

Lifted

9:40 PM CDT (02:40 UTC)

On the ground

14 minutes

Path length

7.3 miles (11.7 km)

Path width

250 yards (229 m)

Deaths

0

Injuries

0

Property damage

$50 million

County

Caddo County

Touchdown point

35.164, -98.243

Lift-off point

35.060, -98.220

Record number

0905132026-01

A cold front moved south into Oklahoma during the evening of the 13th and early on the 14th. Widespread thunderstorms developed over much of the eastern two thirds of Oklahoma. Deep moisture and favorable atmospheric conditions allowed for thunderstorms to become severe along and south of the cold. A strong cap over western Oklahoma didn't allow for much development, although thunderstorms were able to develop west during the late evening hours. All forms of severe weather developed as several supercell thunderstorms developed. Hail up to baseball size, wind gusts over 60 mph, and four tornadoes were reported as the evening progressed. Damage was reported, especially with the tornadoes. The worst damage was reported with a tornado that moved from Gracemont to near Anadarko. Luckily, no injuries were reported with any of the damage.

The tornado developed southeast of Gracemont and moved south along and just east of Highway 8/281 toward the east side of Anadarko. Hundreds of trees, power lines/poles, and fences were destroyed along its path, with numerous homes, barns, and outbuildings receiving significant roof and siding damage. More significant damage occurred on the northeast and east sides of Anadarko, with homes sustaining major damage along Country Club Road. The tornadic winds also damaged the roof and walls of a strip mall. The tornado finally lifted 1.5 to 2 miles southeast of Anadarko. In all, monetary damages were estimated at $50 million, which covered both the tornado damage and damage associated with the rear flank downdraft.

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

2 minutes of warning. NWS OUN issued a tornado warning for this county at 02:24 UTC, 2 minutes before the tornado touched down, in force until 02:55 UTC.

The county was under a severe thunderstorm watch, issued at 22:15 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 Moderate Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 01:02 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.

Chickasha Municipal Airport (CHK), 24 km from the path, in the two hours either side.

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

The Norman radar (KTLX), 90 km away, was scanning. The volume nearest the touchdown began at 02:24 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 2009 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.