Tornadoes · United States · Oklahoma · 2017
Unrated tornado, Devol to Cookietown, Oklahoma, May 10, 2017
From Devol to Cookietown, this Unrated tornado ran 2.0 miles across Cotton County on May 10, 2017, touching down at 8:36 PM CDT and reaching 100 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 mph
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.
Unratedthis tornado
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
- Unrated
- Date
- May 10, 2017
- Touchdown
- 8:36 PM CDT (01:36 UTC)
- Lifted
- 8:41 PM CDT (01:41 UTC)
- On the ground
- 5 minutes
- Path length
- 2.0 miles (3.2 km)
- Path width
- 100 yards (91 m)
- Deaths
- 0
- Injuries
- 0
- County
- Cotton County
- Touchdown point
- 34.340, -98.630
- Lift-off point
- 34.330, -98.600
- Record number
- 1705101936-01
What the Weather Service recorded
With outflow boundaries floating around the state and a large upper low moving into the region, scattered storms formed across Oklahoma and western north Texas on the evening of the 10th.
Storm chasers observed and photographed a tornado in far northwestern Cotton County. No damage was reported and the specific path is estimated.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The warnings
5 minutes of warning. NWS OUN issued a tornado warning for this county at 01:31 UTC, 5 minutes before the tornado touched down, in force until 02:00 UTC.
The county was under a tornado watch, issued at 19:43 UTC and running to 03:00 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 19:43 UTC | 03:00 UTC | Tornado Watch | OUN |
| 00:36 UTC | 01:30 UTC | Severe Thunderstorm Warning | OUN |
| 01:28 UTC | 02:30 UTC | Severe Thunderstorm Warning | OUN |
| 01:31 UTC | 02:00 UTC | Tornado Warning | OUN |
| 01:55 UTC | 04:22 UTC | Flood Advisory | OUN |
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 01:00 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.
Norman, OK (KOUN), 00:00Z
1.6 hours before the tornado, 148 km from the path. May 11, 2017.
- Mixed-layer CAPE
- 1639 J/kg
- Mixed-layer CIN
- -10 J/kg
- Surface CAPE
- 1961 J/kg
- Mixed-layer LCL
- 514 m above ground
- 0-6 km bulk shear
- 61 kt
- 0-1 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- 175 m²/s²
- 0-3 km storm-relative helicity
- 136 m²/s²
- Significant tornado parameter
- 1.5
- Supercell composite
- 5.6
- 0-3 km lapse rate
- 5.5 K/km
Norman, OK (KOUN), 12:00Z
10.4 hours after it, 148 km from the path. May 11, 2017.
- Mixed-layer CAPE
- 592 J/kg
- Mixed-layer CIN
- -121 J/kg
- Surface CAPE
- 1785 J/kg
- Mixed-layer LCL
- 1262 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 106 m²/s²
- 0-3 km storm-relative helicity
- 91 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.8
- 0-3 km lapse rate
- 5.6 K/km
The radar
The Altus AFB radar (KFDR), 33 km away, was scanning. The volume nearest the touchdown began at 01:38 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 |
|---|---|---|---|---|
| 00:20 UTC | HAIL 1 | Headrick | Jackson, OK | |
| 00:58 UTC | HAIL 1 | Frederick | Tillman, OK | |
| 00:59 UTC | TSTM WND GST 72 | 3 Se Frederick | Tillman, OK | |
| 01:04 UTC | TSTM WND GST 72 | 3 Se Frederick | Tillman, OK | |
| 01:05 UTC | TORNADO | 6 E Davidson | Tillman, OK | |
| 01:29 UTC | TORNADO | 6 E Loveland | Tillman, OK | MEDIA CHASERS AND SPOTTERS REPORTED A TORNADO THAT CROSSED HIGHWAY 36. |
| 01:41 UTC | TORNADO | 7 Sse Chattanooga | Cotton, OK | FROM PENN STATE STORM CHASE TEAM. RADAR INDICATED THE TORNADO LIKELY MOVED NEAR THE TILLMAN-COTTON COUNTY LINE. |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2017 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are
The other tornadoes of May 10, 2017
13 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| May 10 | 3:27 AM CDT | EF1 | Armstrong, TX | 2.8 | 180 | |||
| May 10 | 4:01 AM CDT | EF1 | Gray, TX | 2.6 | 50 | |||
| May 10 | 12:37 PM MDT | EF0 | Colfax, NM | 1.7 | 50 | |||
| May 10 | 2:46 PM CDT | EF0 | Van Buren, IA | 2.8 | 50 | |||
| May 10 | 2:54 PM CDT | Unrated | Motley, TX | 0.0 | 10 | |||
| May 10 | 3:37 PM CDT | Unrated | Cottle, TX | 0.0 | 10 | |||
| May 10 | 3:58 PM CDT | Unrated | Cottle, TX | 1.1 | 25 | |||
| May 10 | 4:44 PM CDT | Unrated | Hall, TX | 0.4 | 50 | |||
| May 10 | 7:49 PM CDT | EF0 | Macon, IL | 0.1 | 20 | $8,000 | ||
| May 10 | 8:05 PM CDT | EF0 | Tillman, OK | 0.3 | 30 | |||
| May 10 | 8:31 PM CDT | Unrated | Tillman, OK | 0.3 | 50 | |||
| May 10 | 10:58 PM CDT | Unrated | Val Verde, TX | 0.1 | 10 | |||
| May 10 | 12:34 AM CDT | EF0 | Newton, MO | 1.0 | 100 | $100,000 |
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.