Tornadoes · United States · Colorado · 2010
EF0 tornado, Otis to Elba, Colorado, August 9, 2010
From Otis to Elba, this EF0 tornado ran 0.0 miles across Washington County on August 9, 2010, touching down at 7:42 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 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
- August 9, 2010
- Touchdown
- 7:42 PM MDT (01:42 UTC)
- Path length
- 0.0 miles (0.0 km)
- Path width
- 50 yards (46 m)
- Deaths
- 0
- Injuries
- 0
- County
- Washington County
- Touchdown point
- 40.092, -102.986
- Lift-off point
- 40.092, -102.986
- Record number
- 1008091942-01
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.
What forecasters said that day
The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Denver/Boulder, CO wrote its last area forecast discussion before the tornado touched down at Aug 9, 3:10 PM MDT, 4 hours 32 minutes earlier.
Area forecast discussion, Aug 9, 3:10 PM MDT, 4 hours 32 minutes before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 310 PM MDT MON AUG 9 2010 .SHORT TERM...MAIN PORTION OF UPPER LEVEL DISTURBANCE IS CROSSING OVER THE MOUNTAINS AT THE PRESENT TIME WITH WIDESPREAD CONVECTIVE SHOWER DEVELOPMENT IN THE PAST HOUR OR SO. SOUTHERLY UPPER LEVEL JET IS MOVING THE SHOWER ACTIVITY ALONG AT A 20 MPH CLIP...BUT TRAINING OF STORM ACTIVITY THROUGH THE EVENING WILL BE QUITE POSSIBLE. EARLIER TODAY...SKIES CLEARED BEHIND THE PASSAGE OF THE LEAD SHORT WAVE...WHICH GAVE A FAIR AMOUNT OF WARMING ON THE PLAINS. MODEL SOUNDINGS SHOWED THE AIRMASS DESTABILIZING AFTER 21Z WITH CAPE VALUES JUMPING TO 1500-2000 J/KG DURING THE EVENING. CURRENT LAPS ANALYSIS SHOWS CAPE VALUES OF 1500 J/KG OVER WELD COUNTY. PRECIPITABLE WATER VALUES ACROSS THE PLAINS HAVE CLIMBED TO 1.10-1.25 INCHES WITH MODEL SOUNDINGS FORECASTING VALUES AROUND 1.20 INCHES THROUGH THE EVENING. LOCALLY HEAVY RAIN WILL BE PRIMARY THREAT FROM THE STORMS...GIVEN THE FREEZING LEVELS ARE AROUND 16500 FEET. TRAINING OF STORMS WILL ALSO MAKE IT POSSIBLE FOR LOCATIONS TO RECEIVE MORE THAN ONE EPISODE OF HEAVY RAIN. BACK EDGE OF THE SHORT WAVE SHOULD BE MOVING OUT ACROSS THE PLAINS BY 06Z. CONDITIONS SHOULD IMPROVE RAPIDLY DURING THE OVER NIGHT HOURS AS STRONG SUBSIDENCE MOVES OVER THE STATE. MUCH DRIER AND WARMER CONDITIONS WILL MOVE OVER THE STATE ON TUESDAY WITH 700 MB TEMPERATURES JUMPING ABOVE +16C. HIGH TEMPERATURES ON THE PLAINS SHOULD HAVE NO PROBLEM REACHING THE LOWER 90S. .LONG TERM...LOCAL AIRMASS WILL CONTINUE TO WARM AND DRY TUESDAY NIGHT THRU WEDNESDAY AS MID-LEVELS STABILIZE AND THE MEAN 700-500MB FLOW ASSUMES A NEAR ZONAL COMPONENT WITH PASSAGE OF A FLAT SHORTWAVE RIDGE. STG DIABATIC HEATING AND AMBIENT LOW-LEVEL MOISTURE SHOULD STILL BE SUFFICIENT TO GENERATE AT LEAST ISOLATED LATE DAY T-STORM COVERAGE OVER AND IMMEDIATELY ADJACENT TO THE HIGH MTN TERRAIN ON WEDNESDAY. HOWEVER WITH PREVAILING PW VALUES FALLING BELOW 0.70 INCH...ANY RAINFALL AMTS SHOULD BE LIGHT. AS FAR AS TEMPS...WITH 700MB TEMPS WARMING TO AROUND 18.5C...SHOULD SEE MAX TEMPS ON THE PLAINS UP IN THE 90S WITH THE WARMEST READINGS ACROSS THE FAR NORTHEAST. HIGH COUNTRY READINGS WILL RANGE FM THE 80S IN THE VALLEYS TO THE 60S UP HIGH. ON THURSDAY...THE UPPER RIDGE OVER COLORADO SHIFTS EASTWARD BY HALF A STATE ALLOWING WINDS ALOFT TO BECOME SOUTHWESTERLY. TROPICAL MOISTURE BEING EXPELLED BY ONCE TROPICAL STORM ESTELLE IN THE EASTERN PACIFIC WILL BE CARRIED NORTH BY THIS FLOW REACHING NRN COLORADO DURING THE DAY. PW VALUES JUMP AS THIS PLUME OF MOISTURE DEEPENS. IT LOOKS AS THOUGH WE COULD SEE A REPEAT OF THE BANDED T-STORM ACTIVITY WE EXPECT TO SEE ACROSS THE REGION LATER TODAY. LOCALLY HEAVY RAINFALL WILL NOT BE OUT OF THE QUESTION... PARTICULARLY EAST OF THE I-25 URBAN CORRIDOR. AS FOR TEMPS THAT DAY...MID AND UPPER LVL ATMOSPHERE STILL QUITE WARM. MOS TEMP GUIDANCE IS INDICATING MAX TEMP READINGS IN THE LOWER TO MID 90S ON THE PLAINS. HOWEVER SHOULD CLOUD COVER DVLP SOONER THAN EXPECTED... MAY NOT SEE TEMP MUCH ABOVE 90 DEGS. FOR NOW WILL HANG ONTO LOWER 90S AS A RULE. BY FRIDAY...A MAJORITY OF THE MODELS SHOW THE UPPER RIDGE BEING REPLACED BY AN UPPER TROUGH WHICH QUICKLY DROPS SEWRD OUT OF THE PACIFIC NORTHWEST. 700-500MB TEMPS COOL BY AT LEAST 2C DURING THE DAY. THIS WOULD EQUATE TO A 3-5F DROP IN MAX SFC TEMPS. FURTHERMORE THE MOISTURE PLUME SHIFTS WELL EAST OF THE STATE RESULTING IN MUCH DRIER CONDITIONS AREAWIDE. PRECIP CHANCES ALMOST NIL EAST OF THE MTNS WHILE THE HIGHER TERRAIN MAY ONLY SEE ISOLATED LATE DAY CONVECTION. FOR THE WEEKEND...THE UPPER TROUGH CONTINUES TO MOVE TO OUR EAST OPENING THE DOOR TO A COUPLE WEAK COLD FRONTS SLIDING DOWN THE EAST SLOPE OF THE ROCKIES. THIS SHOULD KEEP TEMPS ESPLY EAST OF THE MTNS AVERAGE TO SLIGHTLY BELOW AVERAGE THRU THE PERIOD. PRECIP CHANCES ALSO EXPECTED TO REMAIN ON THE LOW SLIDE DURING THE PERIOD WITH AS THE ATMOSPHERE SLOWLY DRIES OUT. && .AVIATION...TSTMS WILL CONTINUE THROUGH THE EVENING AS AN UPPER LEVEL WEATHER DISTURBANCE MOVES OVER THE STATE. AIRPORT AND ARRIVAL/DEPARTURE GATES SHOULD BE IMPACTED THROUGH ABOUT 03Z. THUNDERSTORMS WILL BE MOVING IN A NORTH-NORTHEAST DIRECTION AT ABOUT 20 MPH. UPPER FLOW PATTERN WILL MAKE IT POSSIBLE FOR MULTIPLE WAVES OF STORMS TO DEVELOP AND MOVE ACROSS THE METRO AREA THROUGH THE EVENING. MVFR CIGS AND VSBYS WILL BE POSSIBLE DUE TO MODERATE-HEAVY RAIN SHOWERS. DRIER AND MORE SUBSIDENT AIR WILL BEGIN MOVING OVER THE AREA AFTER 06Z WITH SKIES CLEARING AND WINDS RETURNING TO DRAINAGE PATTERN. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. KDRBY/BAKER
Hazardous weather outlook, Aug 9, 11:07 AM MDT, 8 hours 35 minutes before
HAZARDOUS WEATHER OUTLOOK...DELAYED NATIONAL WEATHER SERVICE DENVER CO 1107 AM MDT MON AUG 09 2010 COZ030>051-101200- JACKSON COUNTY BELOW 9000 FEET-WEST JACKSON AND WEST GRAND COUNTIES ABOVE 9000 FEET-GRAND AND SUMMIT COUNTIES BELOW 9000 FEET-SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/ NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET-SOUTH AND SOUTHEAST GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/GILPIN/CLEAR CREEK/ SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE 9000 FEET-LARIMER AND BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-JEFFERSON AND WEST DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR CREEK/NORTHEAST PARK COUNTIES BELOW 9000 FEET-CENTRAL AND SOUTHEAST PARK COUNTY-LARIMER COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY-BOULDER AND JEFFERSON COUNTIES BELOW 6000 FEET/WEST BROOMFIELD COUNTY-NORTH DOUGLAS COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND ARAPAHOE COUNTIES/ EAST BROOMFIELD COUNTY-ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES ABOVE 6000 FEET-NORTHEAST WELD COUNTY-CENTRAL AND SOUTH WELD COUNTY-MORGAN COUNTY-CENTRAL AND EAST ADAMS AND ARAPAHOE COUNTIES- NORTH AND NORTHEAST ELBERT COUNTY BELOW 6000 FEET/NORTH LINCOLN COUNTY-SOUTHEAST ELBERT COUNTY BELOW 6000 FEET/SOUTH LINCOLN COUNTY-LOGAN COUNTY-WASHINGTON COUNTY-SEDGWICK COUNTY-PHILLIPS COUNTY- 1107 AM MDT MON AUG 09 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT LIGHT RAIN SHOWERS FROM THIS MORNING HAVE MOVED OUT OF THE REGION LEAVING BEHIND MOSTLY SUNNY SKIES. HOWEVER...AN UPPER LEVEL WEATHER DISTURBANCE REMAINS OVER THE CENTRAL PART OF THE STATE WHICH WILL PRODUCE ADDITIONAL SHOWERS AND THUNDERSTORMS LATER THIS AFTERNOON. STRONG DAYTIME HEATING AND A STILL MOIST AIRMASS WILL COMBINE WITH THE UPPER LEVEL DISTURBANCE TO PRODUCE THE SHOWER ACTIVITY. THUNDERSTORMS WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL WITH RATES UP TO AN INCH AND A HALF IN 30 MINUTES. STORM MOTIONS OUT OF THE SOUTH TO SOUTHWEST WILL ALSO MAKE IT POSSIBLE FOR MULTIPLE ROUNDS OF STORM DEVELOPMENT THROUGH THE EVENING HOURS. THE PASSAGE OF MORE THAN A SINGLE STORM WILL BE POSSIBLE AT ANY GIVEN LOCATION. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY DRIER AND WARMER CONDITIONS ARE EXPECTED FOR LATER THIS WEEK WITH THE EASTWARD SHIFT OF THE MONSOONAL MOISTURE PLUME. HOWEVER STRONG DAYTIME HEATING MAY STILL MANAGE TO PRODUCE ISOLATED TO EVEN SCATTERED THUNDERSTORMS EACH AFTERNOON AND EVENING...MAINLY OVER AND NEAR THE HIGH MOUNTAIN TERRAIN. ANTICIPATE ABOVE AVERAGE TEMPERATURES THROUGH FRIDAY WITH A RETURN TO MORE SEASONAL TEMPERATURES BY THIS WEEKEND. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. HOWEVER...REPORTS OF HEAVY RAINFALL WILL BE APPRECIATED. DANKERS/BAKER
In the hours before
Local storm report, Aug 9, 6:09 PM MDT, 1 hour 33 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
609 PM MDT MON AUG 09 2010
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0523 PM HAIL 1 E GALETON 40.52N 104.56W
08/09/2010 M0.75 INCH WELD CO TRAINED SPOTTER
COUNTY ROAD 51 BETWEEN CO392 AND WELD COUNTY RD 74--6 TO
8 AREAS WITH 6 TO 8 INCHES OF WATER ON ROAD. 2.53 INCHES
MEASURED RAINFALL AT HIS LOCATION.
0451 PM HEAVY RAIN 8 NE GALETON 40.60N 104.47W
08/09/2010 M1.75 INCH WELD CO TRAINED SPOTTER
1.75 INCHES IN 1 HOUR. WINDS GUSTING TO 45 MPH. PEA SIZE
HAIL ALSO ACCOMPANIED STORM.
&&
BENTONLocal storm report, Aug 9, 7:11 PM MDT, 31 minutes before
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE DENVER CO
711 PM MDT MON AUG 09 2010
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0655 PM HEAVY RAIN 2 W FORT MORGAN 40.27N 103.83W
08/09/2010 U0.00 INCH MORGAN CO TRAINED SPOTTER
STREET FLOODING IN FORT MORGAN. 4 INCHES DEEP. DRAINS
CLOGGED. RAIN AMOUNT NOT GIVEN.
0639 PM TSTM WND GST 3 N PAWNEE PASS 40.67N 103.48W
08/09/2010 M58.00 MPH LOGAN CO TRAINED SPOTTER
NO REPORTED DAMAGE
0523 PM HAIL 1 E GALETON 40.52N 104.56W
08/09/2010 M0.75 INCH WELD CO TRAINED SPOTTER
COUNTY ROAD 51 BETWEEN CO392 AND WELD COUNTY RD 74--6 TO
8 AREAS WITH 6 TO 8 INCHES OF WATER ON ROAD. 2.53 INCHES
MEASURED RAINFALL AT HIS LOCATION.
0451 PM HEAVY RAIN 8 NE GALETON 40.60N 104.47W
08/09/2010 M1.75 INCH WELD CO TRAINED SPOTTER
1.75 INCHES IN 1 HOUR. WINDS GUSTING TO 45 MPH. PEA SIZE
HAIL ALSO ACCOMPANIED STORM.
&&
BENTONThe 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, 32 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
The surface observations
Akron/Washington Co (AKO), 22 km from the path, in the two hours either side.
| Time (UTC) | Temp (°F) | Dew point (°F) | Wind | Gust (kt) | Pressure (mb) | Weather |
|---|---|---|---|---|---|---|
| 00:00 UTC |
From the Iowa Environmental Mesonet's archive of airport observations.
The radar
The Goodland radar (KGLD), 136 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.
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 | 7:44 PM MDT | EF1 | Washington, CO | 0.1 | 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.