EF1 tornado, Stony to Bolivar, Texas, May 7, 2015

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

May 7, 2015

Touchdown

7:45 PM CDT (00:45 UTC)

Lifted

8:05 PM CDT (01:05 UTC)

On the ground

20 minutes

Path length

12.7 miles (20.4 km)

Path width

500 yards (457 m)

Deaths

0

Injuries

0

Property damage

$200,000

Crop damage

$10,000

County

Denton County

Touchdown point

33.255, -97.388

Lift-off point

33.408, -97.265

Record number

1505071845-01

46 damage points were recorded along this path by NWS FWD, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 110 mph.

• large debris deposited on vehicle and swept downstream
• initial debris in fence line
• tree in ditch with saturated ground blown over
• several softwood trees snapped at trunk..approx 1 foot in diameter.

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

A cold front moved south out of the Texas panhandle on May 6th, and was draped across north Texas on the 7th and 8th. The front stalled across the northwestern sections of north Texas and combined to produce severe thunderstorms including large hail, tornadoes, and flash flooding. Flash flooding across Cooke County caused significant impacts, including a late night train derailment.

A National Weather Service damage survey crew found evidence of EF-1 damage, especially near the Bolivar community in western Denton County, Texas. This tornado formed from the same parent supercell which produced a tornado in Wise County. The tornado began in the far southwestern portion of Denton County, producing damage to open farm and ranch land. Once the storm moved into the Bolivar community, damage to several roofs on homes were noted, as well as substantial damage to barns. A metal storage tank was lifted and thrown into the base of a high tension power line, causing the steel beams to collapse.

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

33 minutes of warning. NWS FWD issued a tornado warning for this county at 00:12 UTC, 33 minutes before the tornado touched down, in force until 00:45 UTC.

The county was under a severe thunderstorm watch, issued at 21:33 UTC and running to 05:00 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 Enhanced Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:46 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), 84 km away, was scanning. The volume nearest the touchdown began at 00:46 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 2015 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are

9 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.