Tornadoes · United States · Oklahoma · 2015
EF1 tornado, (Oun)Norman Westheimer Arpt, Oklahoma, May 6, 2015
This EF1 tornado ran 3.3 miles across Cleveland County on May 6, 2015, touching down at 5:53 PM CDT and reaching 1,000 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
- May 6, 2015
- Touchdown
- 5:53 PM CDT (22:53 UTC)
- Lifted
- 6:10 PM CDT (23:10 UTC)
- On the ground
- 17 minutes
- Path length
- 3.3 miles (5.2 km)
- Path width
- 1,000 yards (914 m)
- Deaths
- 0
- Injuries
- 0
- County
- Cleveland County
- Touchdown point
- 35.245, -97.497
- Lift-off point
- 35.291, -97.495
- Record number
- 1505061653-01
The damage survey
432 damage points were recorded along this path by NWS OUN, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF3. The highest wind the damage implies is 149 mph.
- 100 yard length of livestock fence pulled to the north, 1 pole snapped.
- Two signs, tree and fence block (hollow) bent to the southwest. vortex south of here probable based on damage direction.
- 4 signs blown down to the north.
- semi trailer tipped and 2x4 wood debris
Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.
What the Weather Service recorded
A potent Spring storm system took shape across the Southern and Central Plains. Strong surface cyclogenesis took shape during the day, allowing ample moisture to return northward with strong southerly flow. At the same time, a strong upper level shortwave trough allowed strong mid level westerlies to overspread much of the Plains region. With large instability and wind shear, the stage was set for widespread severe storm development. Storms initiated within the open warm sector ahead of the dryline. The first storm developed near Lawton and moved northeast along I-44 into parts of central Oklahoma, resulting in several tornadoes and large hail. Additional supercells spawned tornadoes across northern Oklahoma, and the slow moving nature of storms lead to several occurrences of flash flooding. Storms continued well into the night.
An NWS storm survey found that a tornado touched down near 60th Avenue NW and Robinson Street in northwest Norman. Damage was observed to trees and fencing with damage direction indicating a small vortex. This area was embedded within a large swath of wind damage from the storm's rear-flank downdraft that extended from this area to near Max Westheimer Airport.
A tornado developed south of 36th Avenue NW and Rock Creek Road and traveled basically north near 36th Avenue to near Indian Hills Road through the northwest side of Norman. Numerous house roofs, trees, fences and power poles were damaged in the neighborhoods along 36th Avenue. HVAC equipment was damaged and light poles were downed at the Norman Healthplex hospital at 36th Avenue NW and Tecumseh Road.
From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.
The forecast that day
The Storm Prediction Center had this point in a Enhanced Risk, with a 0.10 chance of a tornado within 25 miles. The outlook in force was issued at 20:00 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.
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 May 6, 3:27 PM CDT, 2 hours 26 minutes earlier.
Area forecast discussion, May 6, 3:27 PM CDT, 2 hours 26 minutes before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 327 PM CDT WED MAY 6 2015 .DISCUSSION... A FEW SEVERE STORMS HAVE ALREADY DEVELOPED IN THE MINIMALLY-CAPPED UNSTABLE/HIGH-SHEAR ATMOSPHERE THAT IS OVER MUCH OF OUR FORECAST AREA. WE EXPECT A FEW SEVERE STORMS TO CONTINUE THROUGH THE EVENING....MAINLY IN THE FORM OF ISOLATED SUPERCELLS. UNLIKE LAST NIGHT...NO ORGANIZED REGION OF HEAVY RAIN IS EXPECTED TONIGHT. SOME STORMS MAY PERSIST PAST MIDNIGHT...BUT THEY WILL LIKELY REMAIN SCATTERED...AND NOT AN ORGANIZED COMPLEX. THE CHANCE FOR RAIN...INCLUDING STRONG/SEVERE STORMS...WILL PERSIST THROUGH THE REMAINDER OF THE WEEK AND WEEKEND. THERE IS VERY LITTLE CHANGE TO PREVIOUS THINKING ABOUT EACH DAY...WITH A LOWER RISK OF SEVERE WEATHER ON THURSDAY...SOMEWHAT HIGHER ON FRIDAY...MUCH HIGHER ON SATURDAY...AND DIMINISHING FROM WEST TO EAST ON SUNDAY. EARLY NEXT WEEK SHOULD BE A COOL AND QUIET PERIOD...FOR A COUPLE OF DAYS...AT LEAST. MOISTURE AND RAIN CHANCES RISE AGAIN MIDWEEK. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 64 77 64 79 / 50 50 60 50 HOBART OK 62 77 64 79 / 50 50 60 50 WICHITA FALLS TX 64 79 66 79 / 60 50 50 50 GAGE OK 62 80 59 80 / 20 40 60 50 PONCA CITY OK 66 79 63 80 / 40 40 70 50 DURANT OK 65 79 67 80 / 40 40 40 40 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && 25/23
Hazardous weather outlook, May 6, 3:28 PM CDT, 2 hours 25 minutes before
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE NORMAN OK 328 PM CDT WED MAY 6 2015 OKZ004>048-050>052-TXZ083>090-072030- 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- 328 PM CDT WED MAY 6 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN... WESTERN...CENTRAL...AND SOUTHERN OKLAHOMA...AND WESTERN NORTH TEXAS. .DAY ONE...REST OF THIS AFTERNOON AND TONIGHT... .THUNDERSTORMS... THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF WESTERN AND CENTRAL OKLAHOMA AND WESTERN NORTH TEXAS. LOCATION... THE ENHANCED RISK AREA IS GENERALLY ALONG AND EAST OF A LINE FROM FREEDOM AND CLINTON... TO ALTUS OKLAHOMA AND BENJAMIN TEXAS... AND THEN WEST OF A LINE FROM PONCA CITY AND STILLWATER... TO SHAWNEE AND SULPHUR... TO ARDMORE OKLAHOMA. THIS INCLUDES PLACES SUCH AS ENID... THE OKLAHOMA CITY METRO... LAWTON... AND WICHITA FALLS. TIMING... THROUGH MIDNIGHT IMPACTS... HAIL UP TO THE SIZE OF BASEBALLS... WIND GUSTS OF 60 TO 70 MPH... A FEW TORNADOES... LOCALLY HEAVY RAINFALL WHICH COULD CAUSE SOME FLOODING... .SPOTTER AND EMERGENCY MANAGEMENT STATEMENT... STORM SPOTTER GROUPS AND EMERGENCY MANAGEMENT PERSONNEL IN THE RISK AREAS SHOULD BE READY FOR SEVERE WEATHER OPERATIONS. DISCUSSION... A FEW THUNDERSTORMS WILL DEVELOP AND MOVE ACROSS PARTS OF OKLAHOMA AND WESTERN NORTH TEXAS. EVEN THOUGH THERE MAY ONLY BE A FEW STORMS... ANY STORM THAT DEVELOPS WILL BE SEVERE DUE TO HIGH INSTABILITY AND STRONG WIND SHEAR. VERY LARGE HAIL... DAMAGING WIND GUSTS... AND TORNADOES WILL BE POSSIBLE. THUNDERSTORM INTENSITY IS EXPECTED TO GRADUALLY WEAKEN DURING THE OVERNIGHT HOURS...BUT STORMS MAY STILL PRODUCE LOCALLY HEAVY RAINFALL AND SOME HAIL. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY... .THUNDERSTORMS... A VERY ACTIVE WEATHER PATTERN WILL REMAIN IN PLACE THROUGH AT LEAST SUNDAY. SEVERE STORMS WILL BE POSSIBLE EACH DAY...ESPECIALLY DURING THE MID AFTERNOON INTO THE LATE EVENING. AT THIS TIME...SATURDAY MAY HAVE THE GREATEST POTENTIAL FOR SEVERE WEATHER AS A STRONG STORM SYSTEM APPROACHES THE SOUTHERN PLAINS. GET GRAPHICS AND MORE DETAILS AT WEATHER.GOV/NORMAN...AND FOLLOW OUR WEATHER FORECAST OFFICE ON TWITTER AND FACEBOOK.
In the hours before
Local storm report, May 6, 4:35 PM CDT, 1 hour 18 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
435 PM CDT WED MAY 06 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0433 PM TORNADO 3 E AMBER 35.16N 97.83W
05/06/2015 GRADY OK BROADCAST MEDIA
&&
FMLocal storm report, May 6, 4:38 PM CDT, 1 hour 15 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
438 PM CDT WED MAY 06 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0437 PM TORNADO 9 SW LAHOMA 36.30N 98.20W
05/06/2015 MAJOR OK STORM CHASER
&&
FMLocal storm report, May 6, 5:24 PM CDT, 29 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
524 PM CDT WED MAY 06 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0510 PM HAIL 3 W TRUSCOTT 33.75N 99.86W
05/06/2015 M1.50 INCH KNOX TX CO-OP OBSERVER
&&
FMLocal storm report, May 6, 5:33 PM CDT, 20 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
533 PM CDT WED MAY 06 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0530 PM HAIL 4 SE CROWELL 33.94N 99.67W
05/06/2015 E1.75 INCH FOARD TX TRAINED SPOTTER
&&
FMLocal storm report, May 6, 5:47 PM CDT, 6 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
547 PM CDT WED MAY 06 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0546 PM HAIL HILLSDALE 36.56N 97.99W
05/06/2015 E1.75 INCH GARFIELD OK EMERGENCY MNGR
&&
FMLocal storm report, May 6, 5:49 PM CDT, 4 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE NORMAN OK
549 PM CDT WED MAY 06 2015
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0546 PM TORNADO 4 WNW NORMAN 35.24N 97.51W
05/06/2015 CLEVELAND OK STORM CHASER
BRIEF TOUCHDOWN AT THE INTERSECTION OF 48TH AND ROBINSON.
&&
FMThe 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), 12:00Z
10.9 hours before the tornado, 10 km from the path. May 6, 2015.
- Mixed-layer CAPE
- 1226 J/kg
- Mixed-layer CIN
- -16 J/kg
- Surface CAPE
- 1997 J/kg
- Mixed-layer LCL
- 562 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 219 m²/s²
- 0-3 km storm-relative helicity
- 308 m²/s²
- Significant tornado parameter
- 1.2
- Supercell composite
- 9.1
- 0-3 km lapse rate
- 6.6 K/km
Norman, OK (KOUN), 00:00Z
1.1 hours after it, 10 km from the path. May 7, 2015.
- Mixed-layer CAPE
- 1821 J/kg
- Mixed-layer CIN
- -7 J/kg
- Surface CAPE
- 2793 J/kg
- Mixed-layer LCL
- 916 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 246 m²/s²
- 0-3 km storm-relative helicity
- 343 m²/s²
- Significant tornado parameter
- 3.0
- Supercell composite
- 19.3
- 0-3 km lapse rate
- 6.8 K/km
The surface observations
Norman/Westheimer (OUN), 4 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 Norman radar (KTLX), 21 km away, was scanning. The volume nearest the touchdown began at 22:55 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 May 6, 2015
47 more were confirmed in the United States that day.
| Date | Time | Rating | Where | Path (mi) | Width (yd) | Deaths | Injuries | Damage |
|---|---|---|---|---|---|---|---|---|
| May 6 | 2:58 AM CDT | EF0 | Creek, OK | 1.5 | 100 | |||
| May 6 | 2:24 PM CDT | EF0 | Lincoln, KS | 10.7 | 100 | $25,000 | ||
| May 6 | 2:45 PM CDT | EF0 | Caddo, OK | 2.0 | 50 | |||
| May 6 | 2:53 PM CDT | EF0 | Caddo, OK | 0.5 | 50 | |||
| May 6 | 3:31 PM CDT | EF0 | Jewell, KS | 1.0 | 25 | |||
| May 6 | 3:55 PM CDT | EF2 | Jewell, KS | 12.6 | 350 | 1 | $1.5 million | |
| May 6 | 4:18 PM CDT | EF1 | Adams, NE | 3.9 | 300 | $1.5 million | ||
| May 6 | 4:33 PM CDT | EF3 | Grady, OK | 10.3 | 1,500 | |||
| May 6 | 4:37 PM CDT | EF0 | Major, OK | 0.1 | 20 | |||
| May 6 | 4:38 PM CDT | EF1 | Nuckolls, NE | 9.5 | 200 | $250,000 | ||
| May 6 | 4:48 PM CDT | EF0 | Grady, OK to KS, NE | 0.3 | 50 | |||
| May 6 | 4:48 PM CDT | EF2 | Nuckolls, KS to NE | 20.1 | 400 | $4.3 million | ||
| May 6 | 4:49 PM CDT | EF3 | Sedgwick, KS | 16.5 | 300 | 1 | $630,000 | |
| May 6 | 4:54 PM CDT | EF1 | Jewell, KS | 4.3 | 250 | $250,000 | ||
| May 6 | 5:04 PM CDT | EF1 | Jewell, KS | 3.1 | 60 | $5,000 | ||
| May 6 | 5:08 PM CDT | EF1 | Republic, KS | 2.1 | 75 | |||
| May 6 | 5:10 PM CDT | EF0 | Republic, KS | 3.1 | 50 | |||
| May 6 | 5:15 PM CDT | EF0 | Garfield, OK | 0.1 | 10 | |||
| May 6 | 5:20 PM CDT | EF2 | Republic, KS to NE | 36.2 | 800 | $1.0 million | ||
| May 6 | 5:26 PM CDT | EF0 | Thayer, NE | 1.8 | 100 | $500,000 | ||
| May 6 | 5:28 PM CDT | EF0 | Thayer, NE | 1.0 | 30 | |||
| May 6 | 5:33 PM CDT | EF1 | McClain, OK | 1.0 | 200 | |||
| May 6 | 5:38 PM CDT | EF0 | Sedgwick, KS | 0.3 | 50 | |||
| May 6 | 5:45 PM CDT | EF0 | Hall, NE | 0.0 | 25 | |||
| May 6 | 5:46 PM CDT | EF0 | Cleveland, OK | 0.5 | 25 | |||
| May 6 | 6:33 PM CDT | EF0 | Dewey, OK | 0.3 | 30 | |||
| May 6 | 6:41 PM CDT | EF0 | Caddo, OK | 3.5 | 200 | |||
| May 6 | 6:56 PM CDT | EF0 | Grant, OK | 0.3 | 20 | |||
| May 6 | 7:14 PM CDT | EF3 | Republic, KS | 1.9 | 100 | |||
| May 6 | 7:28 PM CDT | EF0 | Republic, KS | 0.0 | 50 | |||
| May 6 | 7:35 PM CDT | EF0 | Harper, KS | 0.3 | 50 | |||
| May 6 | 7:38 PM CDT | EF1 | Republic, KS | 2.4 | 75 | |||
| May 6 | 7:49 PM CDT | EF0 | Grady, OK | 0.5 | 40 | |||
| May 6 | 8:11 PM CDT | EF0 | Grady, OK | 3.5 | 200 | |||
| May 6 | 8:33 PM CDT | EF0 | Cloud, KS | 0.3 | 75 | |||
| May 6 | 8:38 PM CDT | EF0 | Ottawa, KS | 0.0 | 50 | |||
| May 6 | 8:41 PM CDT | EF3 | Oklahoma, OK | 2.0 | 700 | 12 | ||
| May 6 | 8:49 PM CDT | EF2 | Archer, TX | 12.0 | 400 | |||
| May 6 | 8:55 PM CDT | EF0 | Ottawa, KS | 0.3 | 50 | |||
| May 6 | 9:10 PM CDT | EF0 | Washington, KS | 6.0 | 50 | |||
| May 6 | 9:27 PM CDT | EF0 | Cloud, KS | 8.8 | 75 | |||
| May 6 | 9:37 PM CDT | EF0 | Throckmorton, TX | 3.4 | 440 | |||
| May 6 | 9:56 PM CDT | EF1 | Washington, KS | 4.0 | 75 | |||
| May 6 | 10:00 PM CDT | EF0 | Throckmorton, TX | 1.2 | 100 | |||
| May 6 | 10:36 PM CDT | EF0 | Washington, KS | 0.3 | 75 | |||
| May 6 | 10:49 PM CDT | EF1 | Gage, NE | 7.7 | 500 | |||
| May 6 | 11:00 PM CDT | EF0 | Throckmorton, TX | 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.