Tornadoes · United States · Texas · 2015

EF0 tornado, Twin Sisters, Texas, May 27, 2015

This EF0 tornado ran 0.3 miles across Blanco County on May 27, 2015, touching down at 11:46 AM CDT and reaching 10 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  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.

The record

Rating
EF0
Date
May 27, 2015
Touchdown
11:46 AM CDT (16:46 UTC)
Lifted
11:48 AM CDT (16:48 UTC)
On the ground
2 minutes
Path length
0.3 miles (0.5 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
County
Blanco County
Touchdown point
30.000, -98.380
Lift-off point
30.005, -98.379
Record number
1505271046-01

What the Weather Service recorded

An upper level shortwave trough moved through southwesterly flow over Texas. This disturbance provided sufficient lift to initiate isolated convection. Some of these storms produced weak tornadoes, large hail, and heavy rain.

A thunderstorm produced a brief, weak tornado just east of Hwy 281 near the Little Blanco River. No damage was reported.

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

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

Issued (UTC)ExpiredProductOffice
16:19 UTC17:00 UTCSevere Thunderstorm WarningEWX
16:47 UTC17:14 UTCTornado WarningEWX
17:00 UTC17:20 UTCSevere Thunderstorm WarningEWX
17:09 UTC19:10 UTCFlash Flood WarningEWX
00:00 UTC01:57 UTCFlash Flood WatchEWX

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 forecast that day

The Storm Prediction Center had this point in a Marginal Risk. The outlook in force was issued at 16:23 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 air that afternoon

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.

Del Rio, TX (KDLF), 12:00Z

4.8 hours before the tornado, 248 km from the path. May 27, 2015.

Skew-T log-pSkew-T log-p diagram, Del Rio, TX at 12:00Z on 2015-05-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 3197 joules per kilogram, CIN -24, lifted condensation level 633 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Del Rio, TX at 12:00Z on 2015-05-27The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 54 square meters per square second, 0 to 6 km bulk shear 31 knots.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
3197 J/kg
Mixed-layer CIN
-24 J/kg
Surface CAPE
3851 J/kg
Mixed-layer LCL
633 m above ground
0-6 km bulk shear
31 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
54 m²/s²
0-3 km storm-relative helicity
200 m²/s²
Significant tornado parameter
2.4
Supercell composite
13.0
0-3 km lapse rate
4.8 K/km

Open this sounding in Storm Lab

Del Rio, TX (KDLF), 00:00Z

7.2 hours after it, 248 km from the path. May 28, 2015.

Skew-T log-pSkew-T log-p diagram, Del Rio, TX at 00:00Z on 2015-05-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1955 joules per kilogram, CIN -73, lifted condensation level 1338 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Del Rio, TX at 00:00Z on 2015-05-28The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -11 square meters per square second, 0 to 6 km bulk shear 31 knots.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
1955 J/kg
Mixed-layer CIN
-73 J/kg
Surface CAPE
2966 J/kg
Mixed-layer LCL
1338 m above ground
0-6 km bulk shear
31 kt
0-1 km bulk shear
15 kt
0-1 km storm-relative helicity
-11 m²/s²
0-3 km storm-relative helicity
60 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.4
0-3 km lapse rate
5.9 K/km

Open this sounding in Storm Lab

The surface observations

San Antonio (5C1), 43 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
14:55 UTC7771.6160° 8 kt1019
15:15 UTC7771.6160° 9 kt1019
15:35 UTC78.871.6160° 10 kt171019.3
15:55 UTC78.873.4160° 7 kt151019.6
16:15 UTC7771.6140° 7 kt1019.6
16:35 UTC7771.6160° 10 kt1019.6
16:55 UTC78.871.6160° 8 kt1019.6
17:15 UTC78.869.8150° 9 kt161019.6
17:35 UTC78.869.8150° 7 kt161019.6
17:55 UTC80.671.6160° 11 kt161019.3
18:15 UTC80.669.8160° 11 kt141019
18:35 UTC80.668170° 11 kt171018.6

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

The radar

The Austin/San Antonio radar (KEWX), 47 km away, was scanning. The volume nearest the touchdown began at 16:46 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.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
15:39 UTCHAIL 13 Nw Tanglewood ForestTravis, TXQUARTER SIZED HAIL REPORTED AT THE INTERSECTION OF SLAUGHTER LN AND ESCARPMENT BLVD.
16:38 UTCFLASH FLOOD3 W Sunset ValleyTravis, TXJOE TANNER LN AND OLD BEE CAVES RD LOW WATER CROSSINGS HAVE BEEN CLOSED DUE TO FLOODING.
16:46 UTCTORNADO1 Ese Twin SistersBlanco, TXTORNADO REPORTED JUST EAST OF HWY 281 NEAR THE LITTLE BLANCO RIVER. LAT LON LOCATION CORRECTED.
16:46 UTCTORNADO2 W Twin SistersBlanco, TXTORNADO REPORTED JUST EAST OF HWY 281 NEAR THE LITTLE BLANCO RIVER.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2015 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are

The other tornadoes of May 27, 2015

18 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 271:10 PM MDTEF0Yuma, CO0.525
May 273:00 PM CDTEF0Logan, KS2.225
May 273:03 PM CDTEF0Lane, KS0.350
May 274:02 PM CDTEF0Lane, KS1.5100
May 274:21 PM CDTEF0Lane, KS0.875
May 274:24 PM CDTEF0Lane, KS1.4100
May 274:58 PM CDTEF2Hemphill, TX1.41,2003
May 275:10 PM CDTEF0Haskell, KS0.575
May 275:14 PM CDTEF1Haskell, KS2.4150$1.0 million
May 275:45 PM CDTEF0Lane, KS5.0125
May 275:54 PM CDTEF0Finney, KS3.4200
May 276:02 PM CDTEF1Hemphill, TX1.1600
May 276:05 PM CDTEF0Hemphill, TX0.5400
May 276:05 PM CDTEF1Hemphill, TX1.1600
May 276:14 PM CDTEF0Finney, KS2.0100
May 277:33 PM CDTEF0Gray, KS1.075
May 277:35 PM CDTEF0Pecos, TX2.2100
May 277:50 PM CDTEF0Pecos, TX4.1200

What this means

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.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.