EF0 tornado, St Jo, Texas, May 24, 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

May 24, 2011

Touchdown

5:46 PM CDT (22:46 UTC)

Lifted

5:47 PM CDT (22:47 UTC)

On the ground

1 minutes

Path length

0.0 miles (0.0 km)

Path width

30 yards (27 m)

Deaths

0

Injuries

0

County

Montague County

Touchdown point

33.679, -97.505

Lift-off point

33.679, -97.505

Record number

1105241646-01

1 damage points were recorded along this path by NWS FWD, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 70 mph.

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

Three rounds of thunderstorms affected north Texas with 10 tornadoes confirmed. The atmosphere was highly unstable on this day and a High Risk was issued by the Storm Prediction Center for the northwestern counties of north Texas while a Moderate Risk covered much of the rest of north Texas. A strong upper level disturbance approaching from the west interacted with a dryline across the western portions of north Texas, and the first round of storms began to develop around 330 pm in the western counties. The first two rounds of storms remained along and north of Interstate 20 but the third round of storms later that night moved through most of the region as a line of storms. The most significant tornado occurred in the western limits of the city of Denton where EF-2 damage occurred. An EF-1 tornado also occurred in the city of Irving in Dallas County, and softball sized hail fell in the northern portions of the Metroplex. In the city of Dallas, one person died from electrocution after going outside around live, downed wires after a storm had passed.

A brief tornado was reported 2 miles southeast of St. Jo near Highway 82. Some tree damage was reported. This tornado was rated an EF-0 with maximum estimated winds of 70 MPH.

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

11 minutes of warning. NWS FWD issued a tornado warning for this county at 22:35 UTC, 11 minutes before the tornado touched down, in force until 22:54 UTC.

The county was under a tornado watch, issued at 17:48 UTC and running to 02:48 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 High Risk, with a 0.45 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 20:44 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.

The Dallas/Ft Worth radar (KFWS), 124 km away, was scanning. The volume nearest the touchdown began at 22:44 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 TexasEvery tornado in Texas since 1950Warnings in force in Texas 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.