Tornadoes · United States · Wyoming · 2010
EF0 tornado, Wheatland, Wyoming, May 21, 2010
This EF0 tornado ran 0.3 miles across Platte County on May 21, 2010, touching down at 4:59 PM MDT and reaching 20 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 21, 2010
- Touchdown
- 4:59 PM MDT (22:59 UTC)
- Lifted
- 5:01 PM MDT (23:01 UTC)
- On the ground
- 2 minutes
- Path length
- 0.3 miles (0.4 km)
- Path width
- 20 yards (18 m)
- Deaths
- 0
- Injuries
- 0
- County
- Platte County
- Touchdown point
- 42.317, -105.120
- Lift-off point
- 42.317, -105.120
- Record number
- 1005211659-01
What the Weather Service recorded
A deep low pressure system positioned over the intermountain west brought severe weather the the CYS county warning area. Tornadoes, hail, and wind were reported with the storms that formed off the Laramie Range and moved to the east and northeast through Platte and Goshen Counties.
A small rope tornado touched down for roughly 2 minutes. It was spotted by multiple chasers and trained spotters.
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.
The county was under a tornado watch, issued at 20:26 UTC and running to 01:17 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 20:26 UTC | 01:17 UTC | Tornado Watch | CYS |
| 22:42 UTC | 23:11 UTC | Severe Thunderstorm Warning | CYS |
| 23:06 UTC | 00:00 UTC | Tornado Warning | CYS |
| 23:55 UTC | 00:23 UTC | Tornado Warning | CYS |
| 02:45 UTC | 03:20 UTC | Severe Thunderstorm Warning | CYS |
| 03:16 UTC | 12:00 UTC | Flood Advisory | CYS |
| 03:40 UTC | 04:00 UTC | Severe Thunderstorm Warning | CYS |
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 19:53 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.
Rapid City, SD (KUNR), 12:00Z
11.0 hours before the tornado, 266 km from the path. May 21, 2010.
- Mixed-layer CAPE
- 6 J/kg
- Mixed-layer CIN
- 0 J/kg
- Surface CAPE
- 24 J/kg
- Mixed-layer LCL
- 504 m above ground
- 0-6 km bulk shear
- 64 kt
- 0-1 km bulk shear
- 6 kt
- 0-1 km storm-relative helicity
- 21 m²/s²
- 0-3 km storm-relative helicity
- 178 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 5.0 K/km
Rapid City, SD (KUNR), 00:00Z
1.0 hours after it, 266 km from the path. May 22, 2010.
- Mixed-layer CAPE
- 17 J/kg
- Mixed-layer CIN
- -145 J/kg
- Surface CAPE
- 197 J/kg
- Mixed-layer LCL
- 1075 m above ground
- 0-6 km bulk shear
- 63 kt
- 0-1 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- 111 m²/s²
- 0-3 km storm-relative helicity
- 395 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
- 0-3 km lapse rate
- 7.1 K/km
The radar
The Cheyenne radar (KCYS), 132 km away, was scanning. The volume nearest the touchdown began at 22:57 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 |
|---|---|---|---|---|
| 22:51 UTC | HAIL 0.88 | Ese I-25 Exit 92 | Platte, WY | |
| 22:59 UTC | TORNADO | 1 Ne I-25 Exit 92 | Platte, WY | MULTIPLE REPORTS OF ROPE TORNADO ON THE GROUND FOR TWO MINUTES. |
| 23:30 UTC | HAIL 1.75 | 4 Nne Guernsey | Platte, WY | DAMAGE TO VEHICLES WITH WINDSHIELD BUSTED OUT |
| 23:30 UTC | HAIL 1.75 | Ene Hartville | Platte, WY | BROKEN WINDSHIELDS AND OTHER DAMAGE TO VEHICLES |
| 23:55 UTC | TORNADO | 18 Nw Lingle | Goshen, WY | BRIEF TOUCHDOWN OF 30 TO 40 SECONDS. |
| 00:01 UTC | TORNADO | 18 Nnw Lingle | Goshen, WY | BRIEF TORNADO TOUCHDOWN. SEPARATE FROM 555 PM MDT REPORT. |
From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.
This ground now
The live radar over the trackEvery 2010 tornado in WyomingEvery tornado in Wyoming since 1950Warnings in force in Wyoming nowThe forecast where you are
The other tornadoes of May 21, 2010
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.