Tornadoes · United States · Texas · 2007

EF0 tornado, Sonora Allison Arpt, Texas, May 9, 2007

This EF0 tornado ran 1.2 miles across Sutton County on May 9, 2007, touching down at 3:48 PM CDT and reaching 30 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 9, 2007
Touchdown
3:48 PM CDT (20:48 UTC)
Lifted
3:55 PM CDT (20:55 UTC)
On the ground
7 minutes
Path length
1.2 miles (1.9 km)
Path width
30 yards (27 m)
Deaths
0
Injuries
0
County
Sutton County
Touchdown point
30.640, -100.814
Lift-off point
30.634, -100.798
Record number
0705091448-01

What the Weather Service recorded

Severe thunderstorms developed in the afternoon. The thunderstorms affected the Northern Edwards Plateau, the Heartland and the Northwest Hill Country. Another isolated supercell developed in Throckmorton County and produced another tornado. There were other tornadoes reported with the southern storms across the Edwards Plateau and the Northwest Hill Country.

Tornado developed several miles west northwest of Sonora along Ranch Road 1312. The tornado paralleled the road for about a mile before dissipating. No damage was reported.

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

The warnings

21 minutes of warning. NWS SJT issued a tornado warning for this county at 20:27 UTC, 21 minutes before the tornado touched down, in force until 21:15 UTC.

The county was under a tornado watch, issued at 20:32 UTC and running to 23:39 UTC.

Issued (UTC)ExpiredProductOffice
20:27 UTC21:15 UTCTornado WarningSJT
20:30 UTC21:30 UTCSevere Thunderstorm WarningSJT
20:32 UTC23:39 UTCTornado WatchSJT
20:56 UTC22:00 UTCTornado WarningSJT
21:18 UTC00:15 UTCFlash Flood WarningSJT
21:35 UTC22:15 UTCSevere Thunderstorm WarningSJT
21:56 UTC23:00 UTCSevere Thunderstorm WarningSJT

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 Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 22:19 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 (KDRT), 12:00Z

8.8 hours before the tornado, 141 km from the path. May 9, 2007.

Skew-T log-pSkew-T log-p diagram, Del Rio, TX at 12:00Z on 2007-05-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 69 joules per kilogram, CIN -193, lifted condensation level 687 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 2007-05-09The 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 12 square meters per square second, 0 to 6 km bulk shear 16 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
69 J/kg
Mixed-layer CIN
-193 J/kg
Surface CAPE
309 J/kg
Mixed-layer LCL
687 m above ground
0-6 km bulk shear
16 kt
0-1 km bulk shear
16 kt
0-1 km storm-relative helicity
12 m²/s²
0-3 km storm-relative helicity
36 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.3 K/km

Open this sounding in Storm Lab

The surface observations

Sonora Municipal (SOA), 16 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
19:05 UTC6864.410° 4 kt1017.6VCTS
19:25 UTC69.864.420° 5 kt1016.9
19:45 UTC73.464.4160° 7 kt1016.6
20:05 UTC73.464.4150° 10 kt1014.9
20:25 UTC73.460.8140° 10 kt161014.6
20:45 UTC73.462.6140° 11 kt151014.9VCTS
21:05 UTC73.462.6170° 8 kt171014.9VCTS
21:45 UTC5957.2350° 19 kt301016.6+TSRA
22:05 UTC57.255.4340° 9 kt151017.9VCTS +RA
22:25 UTC57.255.4360° 13 kt161016.9VCTS +RA
22:45 UTC57.255.4350° 9 kt1016.9-RA

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

The radar

The San Angelo radar (KSJT), 87 km away, was scanning. The volume nearest the touchdown began at 20:45 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
20:48 UTCTORNADO11 Wnw SonoraSutton, TX
21:24 UTCHAIL 11 Sw EldoradoSchleicher, TX
21:45 UTCFLASH FLOODOzonaCrockett, TXFIRE DEPARTMENT REPORTED FLOODING OF STREETS IN OZONA DUE TO FLOODING OF DRAW. OFFICIALS HAVE CLOSED HIGHWAY 163 SOUTH OF OZONA AND HIGHWAY 290 EAST OF OZONA DUE TO FLOODING. THE INTERSECTION OF HIGHWAYS 163 AND 137 3 MI

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

This ground now

The live radar over the trackEvery 2007 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are

The other tornadoes of May 9, 2007

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 94:04 PM CDTEF0Throckmorton, TX0.920
May 96:12 PM CDTEF0Menard, TX1.540

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.