Tornadoes · United States · Texas · 2011
EF0 tornado, Manchester to Blakeney, Texas, May 20, 2011
From Manchester to Blakeney, this EF0 tornado ran 1.6 miles across Red River County on May 20, 2011, touching down at 5:36 PM CDT and reaching 50 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.
EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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 20, 2011
- Touchdown
- 5:36 PM CDT (22:36 UTC)
- Lifted
- 5:38 PM CDT (22:38 UTC)
- On the ground
- 2 minutes
- Path length
- 1.6 miles (2.6 km)
- Path width
- 50 yards (46 m)
- Deaths
- 0
- Injuries
- 0
- County
- Red River County
- Touchdown point
- 33.847, -95.122
- Lift-off point
- 33.864, -95.103
- Record number
- 1105201636-01
What the Weather Service recorded
The storm environment for May 20th involved a very unstable atmosphere, especially across the northern third of Northeast Texas, Southeast Oklahoma and Southwest Arkansas. The atmosphere was weakly capped which resulted in the development of scattered severe thunderstorms across the region. An upper level disturbance moved across the region as well and with cold temperatures aloft resulting in steep mid level lapse rates...a majority of the storms produced large hail. High shear was also in place in the mid and lower levels of the atmosphere which provided a wind threat as well. Some of these storms produced tornadoes across the region.
The National Weather Service conducted a storm survey in Red River County and concluded that damage was the result of an EF0 tornado. The tornado first touched down over a wooded area east of Manchester damaging a few trees. The tornado moved northeast crossing FM 195 where a few small trees were snapped and a few small trees and limbs. The tornado ended north of FM 195. The Maximum winds are estimated at 65-70 mph.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
9 minutes of warning. NWS SHV issued a tornado warning for this county at 22:27 UTC, 9 minutes before the tornado touched down, in force until 23:15 UTC.
The county was under a tornado watch, issued at 16:08 UTC and running to 22:56 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 16:08 UTC | 22:56 UTC | Tornado Watch | SHV |
| 22:27 UTC | 23:15 UTC | Tornado Warning | SHV |
| 22:56 UTC | 02:23 UTC | Tornado Watch | SHV |
| 23:55 UTC | 00:42 UTC | Severe Thunderstorm Warning | SHV |
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 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 20:00 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.
Shreveport, LA (KSHV), 12:00Z
10.6 hours before the tornado, 199 km from the path. May 20, 2011.
- Mixed-layer CAPE
- 2656 J/kg
- Mixed-layer CIN
- -44 J/kg
- Surface CAPE
- 2171 J/kg
- Mixed-layer LCL
- 648 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 151 m²/s²
- 0-3 km storm-relative helicity
- 231 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 5.7 K/km
Shreveport, LA (KSHV), 00:00Z
1.4 hours after it, 199 km from the path. May 21, 2011.
- Mixed-layer CAPE
- 1940 J/kg
- Mixed-layer CIN
- -23 J/kg
- Surface CAPE
- 3204 J/kg
- Mixed-layer LCL
- 1407 m above ground
- 0-6 km bulk shear
- 19 kt
- 0-1 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 116 m²/s²
- 0-3 km storm-relative helicity
- 248 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 9.0
- 0-3 km lapse rate
- 7.8 K/km
The surface observations
Idabel (4O4), 24 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 20:47 UTC | 80.6 | 69.8 | 150° 14 kt | 20 | 1007.5 | |
| 21:06 UTC | 80.6 | 71.6 | 150° 8 kt | 1007.5 | ||
| 21:26 UTC | 80.6 | 69.8 | 150° 9 kt | 15 | 1007.1 | |
| 21:46 UTC | 82.4 | 71.6 | 140° 14 kt | 18 | 1006.8 | |
| 22:07 UTC | 80.6 | 69.8 | 140° 10 kt | 18 | 1007.1 | VCTS |
| 22:27 UTC | 80.6 | 69.8 | 120° 3 kt | 1007.5 | VCTS | |
| 22:47 UTC | 69.8 | 60.8 | 340° 14 kt | 22 | 1008.8 | |
| 23:07 UTC | 64.4 | 60.8 | 320° 18 kt | 26 | 1009.8 | VCTS |
| 23:27 UTC | 62.6 | 60.8 | 320° 14 kt | 17 | 1009.1 | TS |
| 23:47 UTC | 62.6 | 60.8 | 280° 5 kt | 18 | 1009.1 | TS |
| 00:07 UTC | 62.6 | 60.8 | 290° 12 kt | 16 | 1010.2 | VCTS |
| 00:27 UTC | 64.4 | 62.6 | 330° 4 kt | 8 | 1008.8 | TS |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Western Arkansas radar (KSRX), 174 km away, was scanning. The volume nearest the touchdown began at 22:34 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) | Report | Where | County | Remark |
|---|---|---|---|---|
| 22:14 UTC | HAIL 1 | Detroit | Red River, TX | |
| 22:36 UTC | TORNADO | 10 S Valliant | Red River, TX | A EF0 TORNADO BRIEFLY TOUCHED DOWN NORTHEAST OF MANCHESTER TEXAS ALONG FM 195 KNOCKING DOWN A FEW SMALL TREES AND SNAPPING LARGE BRANCHES. THE WEAK TORNADO WAS ON THE GROUND FOR 1.5 MILES AND WAS APPROXIMATELY 50 YARDS W |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2011 tornado in TexasEvery tornado in Texas since 1950Warnings in force in Texas nowThe forecast where you are
The other tornadoes of May 20, 2011
5 more were confirmed in the United States that day.
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.