Tornadoes · United States · Colorado · 2010
EF1 tornado, Otis to Elba, Colorado, August 9, 2010
From Otis to Elba, this EF1 tornado ran 0.1 miles across Washington County on August 9, 2010, touching down at 7:44 PM MDT 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 mph
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mphthis tornado
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
- EF1
- Date
- August 9, 2010
- Touchdown
- 7:44 PM MDT (01:44 UTC)
- Path length
- 0.1 miles (0.2 km)
- Path width
- 50 yards (46 m)
- Deaths
- 0
- Injuries
- 0
- County
- Washington County
- Touchdown point
- 39.960, -102.960
- Lift-off point
- 39.960, -102.960
- Record number
- 1008091944-01
What the Weather Service recorded
Severe thunderstorms produced heavy rain and damaging winds across parts of Logan, Morgan, Phillips, Washington and Weld Counties. The strong winds downed trees and power lines. In addition, two tornadoes touched down. One of the tornadoes destroyed half of a barn. Heavy rain produced flash flooding in Fort Morgan.
A tornado touched down briefly in an open field but did no damage.
A tornado touched down and destroyed half of a barn.
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 severe thunderstorm watch, issued at 23:36 UTC and running to 03:49 UTC.
| Issued (UTC) | Expired | Product | Office |
|---|---|---|---|
| 23:36 UTC | 03:49 UTC | Severe Thunderstorm Watch | BOU |
| 00:56 UTC | 01:16 UTC | Tornado Warning | BOU |
| 01:21 UTC | 02:00 UTC | Severe Thunderstorm Warning | BOU |
| 01:27 UTC | 02:30 UTC | Severe Thunderstorm Warning | BOU |
| 01:45 UTC | 01:59 UTC | Tornado Warning | BOU |
| 01:54 UTC | 03:00 UTC | Severe Thunderstorm Warning | BOU |
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 00:59 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.
Denver, CO (KDNR), 00:00Z
1.7 hours before the tornado, 25 km from the path. August 10, 2010.
- Mixed-layer CAPE
- 7 J/kg
- Mixed-layer CIN
- -91 J/kg
- Surface CAPE
- 22 J/kg
- Mixed-layer LCL
- 1673 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km bulk shear
- 1 kt
- 0-1 km storm-relative helicity
- -1 m²/s²
- 0-3 km storm-relative helicity
- 80 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
- 0-3 km lapse rate
- 7.5 K/km
Denver, CO (KDNR), 12:00Z
10.3 hours after it, 25 km from the path. August 10, 2010.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- -72016 J/kg
- Surface CAPE
- 221 J/kg
- Mixed-layer LCL
- 2387 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- -38 m²/s²
- 0-3 km storm-relative helicity
- 53 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
- 0-3 km lapse rate
- 5.5 K/km
The surface observations
Akron/Washington Co (AKO), 33 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 23:53 UTC | 86 | 61 | 130° 18 kt | 23 | 1014.6 | |
| 00:53 UTC | 80 | 63 | 140° 5 kt | 1015.2 | ||
| 01:25 UTC | 66.2 | 60.8 | 290° 20 kt | 28 | 1015.9 | -RA |
| 01:53 UTC | 64 | 62 | 280° 23 kt | 37 | 1015.9 | -RA |
| 01:55 UTC | 64.4 | 62.6 | 280° 21 kt | 37 | 1016.3 | -RA |
| 02:07 UTC | 62.6 | 62.6 | 300° 13 kt | 27 | 1017.6 | -RA BR |
| 02:53 UTC | 63 | 62 | 20° 9 kt | 1018.3 | -RA | |
| 03:00 UTC | 62.6 | 62.6 | 40° 9 kt | 1018.6 | -RA | |
| 03:14 UTC | 62.6 | 60.8 | 30° 6 kt | 1018.3 | -RA | |
| 03:33 UTC | 62.6 | 60.8 | 40° 9 kt | 1018.6 | RA | |
| 03:42 UTC | 62.6 | 60.8 | 10° 8 kt | 1018.6 | -RA |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Goodland radar (KGLD), 126 km away, was scanning. The volume nearest the touchdown began at 01:42 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 |
|---|---|---|---|---|
| 00:25 UTC | TSTM WND DMG | 6 Sw Kirk | Kit Carson, CO | SEVERAL 1 TO 1.5 INCH DIAMETER TREE LIMBS DOWN. |
| 00:25 UTC | HAIL 0.88 | 6 Sw Kirk | Kit Carson, CO | |
| 01:20 UTC | HAIL 1 | 13 S Yuma | Yuma, CO | |
| 01:39 UTC | TSTM WND GST 66 | 1 W Yuma | Yuma, CO | CWOP STATION |
| 01:42 UTC | TORNADO | 7 Se Akron | Washington, CO | 2 TORNADOES ON THE GROUND 5 MILES EAST. NO DAMAGE REPORTED. |
| 01:42 UTC | HAIL 1 | Yuma | Yuma, CO | |
| 01:44 UTC | TORNADO | 13 S Otis | Washington, CO | A SPOTTER REPORTED TO THE SHERIFF THAT A TORNADO HAD DESTROYED HALF OF HER BARN. NO REPORT OF INJURIES. |
| 02:01 UTC | TSTM WND GST 69 | 1 W Yuma | Yuma, CO | FROM CWOP STATION |
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 ColoradoEvery tornado in Colorado since 1950Warnings in force in Colorado nowThe forecast where you are
The other tornadoes of August 9, 2010
1 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| August 9 | 7:42 PM MDT | EF0 | Washington, CO | 0.0 | 50 |
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.