Tornadoes · United States · Oklahoma · 2015
EF1 tornado, Dacoma, Oklahoma, April 18, 2015
This EF1 tornado ran 0.5 miles across Woods County on April 18, 2015, touching down at 4:06 PM CDT and reaching 40 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
- April 18, 2015
- Touchdown
- 4:06 PM CDT (21:06 UTC)
- Path length
- 0.5 miles (0.8 km)
- Path width
- 40 yards (37 m)
- Deaths
- 0
- Injuries
- 0
- County
- Woods County
- Touchdown point
- 36.549, -98.581
- Lift-off point
- 36.549, -98.581
- Record number
- 1504181506-01
What the Weather Service recorded
As the slow moving upper trough continued eastward, it moved into portions of western Kansas and Oklahoma. A Pacific front/dryline surged eastward during the day, igniting thunderstorms. Given impressive upper level winds, and moderate instability, reports of large hail and damaging winds were widespread and lasted into the night.
Video of a brief tornado was captured by a KOCO-TV storm chaser and by a local resident. The tornado caused snapped trees and damaged a metal barn at a ranch south of Dacoma.
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 Norman, OK wrote its last area forecast discussion before the tornado touched down at Apr 18, 2:31 PM CDT, 1 hour 35 minutes earlier.
Area forecast discussion, Apr 18, 2:31 PM CDT, 1 hour 35 minutes before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 231 PM CDT SAT APR 18 2015 .DISCUSSION... GETTING BUSY... SO THIS WILL BE SHORT. ANOTHER ROUND OF SEVERE STORMS EXPECTED LATER THIS AFTERNOON THROUGH THIS EVENING AS UPPER LOW CONT TO SLOWLY MOVE EAST AND NORTHEAST. THE LOW IS EXPECTED TO OPEN UP AND SHIFT EAST TOMORROW. AS THIS OCCURS A COLD FRONT WITH GUSTY NORTH WINDS WILL SWEEP SOUTHEAST ACROSS THE AREA. COULD SEE A FEW SHOWERS/THUNDERSTORMS UNDER THE UPPER LOW ACROSS NORTHERN OKLAHOMA ON SUNDAY. WITH COLD TEMPS ALOFT ASSOCIATED WITH THIS LOW... COULD SEE SOME SMALL HAIL ASSOCIATED WITH THE STORMS. WILL THEN SEE A COUPLE OF DRY DAYS BEFORE ANOTHER ACTIVE PERIOD BEGINNING TUESDAY AND LINGERING REALLY THROUGH THE REMAINDER OF THE UPCOMING WEEK. NO REAL STRONG SIGNAL FOR SEVERE... BUT IT IS GETTING TO BE LATE APRIL... SO CAN NOT COMPLETELY RULE IT OUT. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 55 72 44 66 / 60 30 0 0 HOBART OK 50 71 42 67 / 30 10 0 0 WICHITA FALLS TX 54 75 45 70 / 30 10 0 0 GAGE OK 47 65 38 65 / 40 20 0 0 PONCA CITY OK 54 71 42 65 / 60 60 10 0 DURANT OK 58 77 49 70 / 60 20 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && 84/30
Hazardous weather outlook, Apr 18, 2:55 PM CDT, 1 hour 11 minutes before
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE NORMAN OK 255 PM CDT SAT APR 18 2015 OKZ004>048-050>052-TXZ083>090-191800- HARPER-WOODS-ALFALFA-GRANT-KAY-ELLIS-WOODWARD-MAJOR-GARFIELD- NOBLE-ROGER MILLS-DEWEY-CUSTER-BLAINE-KINGFISHER-LOGAN-PAYNE- BECKHAM-WASHITA-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-MCCLAIN- CLEVELAND-POTTAWATOMIE-SEMINOLE-HUGHES-HARMON-GREER-KIOWA-JACKSON- TILLMAN-COMANCHE-STEPHENS-GARVIN-MURRAY-PONTOTOC-COAL-COTTON- JEFFERSON-CARTER-JOHNSTON-ATOKA-LOVE-MARSHALL-BRYAN-HARDEMAN- FOARD-WILBARGER-WICHITA-KNOX-BAYLOR-ARCHER-CLAY- 255 PM CDT SAT APR 18 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN... WESTERN...CENTRAL...AND SOUTHERN OKLAHOMA...AND WESTERN NORTH TEXAS. .DAY ONE...THIS AFTERNOON AND TONIGHT... .THUNDERSTORMS... THERE IS AN ENHANCED RISK OF SEVERE STORMS ACROSS MUCH OF OKLAHOMA AND WESTERN NORTH TEXAS. LOCATION... THE ENHANCED RISK AREA IS ALONG AND EAST OF A LINE FROM BUFFALO...TO CHEYENNE...TO MANGUM IN OKLAHOMA...TO QUANAH AND BENJAMIN IN WESTERN NORTH TEXAS....AND WEST OF A LINE FROM MEDFORD...TO OKLAHOMA CITY..TO ARDMORE. THE REMAINDER OF OKLAHOMA AND WESTERN NORTH TEXAS IS IN A SLIGHT RISK. TIMING... THROUGH MIDNIGHT. IMPACTS... HAIL UP TO THE SIZE OF GOLF BALLS TO TENNIS BALLS...AND WIND GUSTS UP TO 70 MPH WILL BE THE MAIN CONCERNS. A COUPLE OF TORNADOES MAY ALSO OCCUR ACROSS MAINLY WESTERN OKLAHOMA AND WESTERN NORTH TEXAS LATE THIS AFTERNOON AND EVENING. DISCUSSION... SCATTERED THUNDERSTORMS HAVE DEVELOPED FROM NORTH CENTRAL INTO WESTERN OKLAHOMA EARLY THIS AFTERNOON. THESE STORMS HAVE DEVELOPED IN AN ENVIRONMENT SUPPORTIVE OF RAPID STORM ORGANIZATION...AND HAVE AT TIMES BECOME SEVERE. THESE STORMS ARE LIKELY TO PERSIST OVER THE NEXT SEVERAL HOURS...WITH ADDITIONAL STORMS DEVELOPING OVER WESTERN OKLAHOMA DOWN INTO WESTERN NORTH TEXAS. LARGE HAIL AND DAMAGING WINDS WILL REMAIN THE MAIN CONCERNS WITH THE STRONGEST STORMS...THOUGH A COUPLE OF TORNADOES WILL ALSO BE POSSIBLE WITH STORMS ACROSS WESTERN OKLAHOMA AND WESTERN NORTH TEXAS. STORMS MAY MERGE INTO ONE OR MORE CLUSTERS THIS EVENING AND TONIGHT... AS THEY MOVE TO THE NORTHEAST. THESE AREAS OF STORMS MAY CONTINUE TO POSE A THREAT OF LARGE HAIL AND DAMAGING WINDS...ALONG WITH LOCALLY HEAVY RAINFALL...AS THEY MOVE THROUGH NORTHERN AND CENTRAL OKLAHOMA. .SPOTTER AND EMERGENCY MANAGEMENT STATEMENT... STORM SPOTTER GROUPS AND EMERGENCY MANAGEMENT PERSONNEL ACROSS THE AREA SHOULD PREPARE FOR SEVERE WEATHER OPERATIONS THIS AFTERNOON THROUGH THIS EVENING. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY... .THUNDERSTORMS... SHOWERS AND THUNDERSTORMS WILL LINGER INTO SUNDAY. SEVERE WEATHER IS UNLIKELY BUT A FEW STORMS MAY BECOME STRONG PRODUCING SMALL HAIL. SHOWER AND THUNDERSTORM CHANCES WILL RETURN MONDAY NIGHT THROUGH FRIDAY...AS A SERIES OF UPPER LEVEL SYSTEMS MOVE ACROSS THE SOUTHERN PLAINS. STRONG TO SEVERE THUNDERSTORM POTENTIAL WILL LIKELY EXIST FOR A TIME FROM MID TO LATE NEXT WEEK. GET GRAPHICS AND MORE DETAILS AT WEATHER.GOV/NORMAN...AND FOLLOW OUR WEATHER FORECAST OFFICE ON TWITTER AND FACEBOOK. EM/MBS/AUSTIN
In the hours before
Special weather statement, Apr 18, 3:08 PM CDT, 58 minutes before
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</html>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.
Dodge City, (KDDC), 12:00Z
9.1 hours before the tornado, 179 km from the path. April 18, 2015.
- Mixed-layer CAPE
- 192 J/kg
- Mixed-layer CIN
- -124 J/kg
- Surface CAPE
- 439 J/kg
- Mixed-layer LCL
- 897 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km bulk shear
- 11 kt
- 0-1 km storm-relative helicity
- -48 m²/s²
- 0-3 km storm-relative helicity
- 9 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.0
- 0-3 km lapse rate
- 6.1 K/km
Dodge City, (KDDC), 00:00Z
2.9 hours after it, 179 km from the path. April 19, 2015.
- Mixed-layer CAPE
- 137 J/kg
- Mixed-layer CIN
- -11 J/kg
- Surface CAPE
- 564 J/kg
- Mixed-layer LCL
- 2335 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km bulk shear
- 9 kt
- 0-1 km storm-relative helicity
- -3 m²/s²
- 0-3 km storm-relative helicity
- 4 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
- 0-3 km lapse rate
- 9.1 K/km
The surface observations
Alva Regional Airport (AVK), 26 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 Vance AFB radar (KVNX), 46 km away, was scanning. The volume nearest the touchdown began at 21:03 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 2015 tornado in OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are
The other tornadoes of April 18, 2015
3 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.