Tornadoes · United States · Oregon · 2009

EF1 tornado, Cayuse to Thorn Hollow, Oregon, May 6, 2009

From Cayuse to Thorn Hollow, this EF1 tornado ran 1.6 miles across Umatilla County on May 6, 2009, touching down at 4:55 PM PDT and reaching 40 yards wide. It killed nobody, and did $50,000 of property damage.

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.

  1. EF065 to 85 mph

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. EF186 to 110 mphthis tornado

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. 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.

  4. 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.

  5. EF4166 to 200 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. 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.

  7. 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, 2009
Touchdown
4:55 PM PDT (23:55 UTC)
Lifted
5:00 PM PDT (00:00 UTC)
On the ground
5 minutes
Path length
1.6 miles (2.6 km)
Path width
40 yards (37 m)
Deaths
0
Injuries
0
Property damage
$50,000
County
Umatilla County
Touchdown point
45.720, -118.516
Lift-off point
45.725, -118.484
Record number
0905061755-01

What the Weather Service recorded

An upper level trough combined with an approaching cold front and daytime heating produced severe thunderstorms. A brief tornado was observed near Adams in Umatilla County also near Wallowa in Wallowa County.

Storm observed by farm workers at Ruggs Ranch. One hundred foot section of workshop metal roof torn off and carried up to 1/2 mile. Fifty-gallon drums thrown up to 1/4 mile. Trees uprooted and limbs down. Wooden plank driven through metal building.

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.

Issued (UTC)ExpiredProductOffice
23:47 UTC00:30 UTCSevere Thunderstorm WarningPDT

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 General Thunderstorms Risk. The outlook in force was issued at 19:58 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.

Spokane, WA (KOTX), 12:00Z

11.9 hours before the tornado, 272 km from the path. May 6, 2009.

Skew-T log-pSkew-T log-p diagram, Spokane, WA at 12:00Z on 2009-05-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -97018, lifted condensation level 1294 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Spokane, WA at 12:00Z on 2009-05-06The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 96 square meters per square second, 0 to 6 km bulk shear 63 knots.1939587897117136Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-97018 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1294 m above ground
0-6 km bulk shear
63 kt
0-1 km bulk shear
19 kt
0-1 km storm-relative helicity
96 m²/s²
0-3 km storm-relative helicity
108 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.5 K/km

Open this sounding in Storm Lab

Spokane, WA (KOTX), 00:00Z

0.1 hours after it, 272 km from the path. May 7, 2009.

Skew-T log-pSkew-T log-p diagram, Spokane, WA at 00:00Z on 2009-05-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1 joules per kilogram, CIN -2, lifted condensation level 583 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Spokane, WA at 00:00Z on 2009-05-07The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 89 square meters per square second, 0 to 6 km bulk shear 46 knots.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
1 J/kg
Mixed-layer CIN
-2 J/kg
Surface CAPE
134 J/kg
Mixed-layer LCL
583 m above ground
0-6 km bulk shear
46 kt
0-1 km bulk shear
16 kt
0-1 km storm-relative helicity
89 m²/s²
0-3 km storm-relative helicity
117 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.5 K/km

Open this sounding in Storm Lab

The radar

The Pendleton radar (KPDT), 28 km away, was scanning. The volume nearest the touchdown began at 23:55 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.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
23:45 UTCTSTM WND DMG1 S PendletonUmatilla, ORPOWER OUTAGE DUE TO TREE BRANCHES DOWN ON POWER LINE. 20 FOOT TALL LILAC TREE UPROOTED AND SHINGLES TORN OFF ROOFS.
23:55 UTCHAIL 1.755 Ese AdamsUmatilla, ORWIND DRIVEN HAIL UP TO GOLF BALL SIZE PUNCHED HOLES IN VINYL SIDING. OCCURRED JUST SOUTH OF TORNADO TRACK.
23:55 UTCTORNADO4 Se AdamsUmatilla, ORNWS TEAM DETERMINED THAT A TORNADO OF EF1 INTENSITY WITH A PATH LENGTH OF 1.6 MILES AND PATH WIDTH OF 40 YARDS OCCURRED FROM 4 SE OF ADAMS TO 5 ESE OF ADAMS FROM 455 PM TO 5 PM PDT. 100 FOOT SECTION OF METAL ROOF FROM WO
00:00 UTCTSTM WND DMG7 Se AdamsUmatilla, ORRANCH REPORTS THUNDERSTORM WINDS TORE LARGE WORKSHOP IN HALF AND CARRIED ROOF 100 YARDS BEFORE DROPPING IT ONTO THE ROOF OF ANOTHER BUILDING. SEVERAL 55 GALLON DRUMS LIFTED AT LEAST 100 FEET INTO AIR BEFORE BEING DROPPED
00:00 UTCHAIL 0.75AdamsUmatilla, ORGROUND WHITE WITH HAIL ON HIGHWAY 11 AT MILEPOST 14. LARGEST HAIL 3/4 INCH.
00:00 UTCHAIL 0.884 Sw AthenaUmatilla, ORHAIL COVERED THE GROUND. LARGEST WAS NICKEL SIZED.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2009 tornado in OregonEvery tornado in Oregon since 1950Warnings in force in Oregon nowThe forecast where you are

The other tornadoes of May 6, 2009

21 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 61:19 AM CDTEF0Arkansas, AR4.425$5,000
May 62:03 AM CDTEF1Phillips, AR0.125$40,000
May 63:34 AM CDTEF1Coahoma, MS0.125$60,000
May 64:52 AM CDTEF1Drew, AR2.1100$50,000
May 67:12 AM CDTEF1Choctaw, MS7.6500$350,000
May 67:47 AM CDTEF1Noxubee, MS5.05002$300,000
May 68:20 AM CDTEF1Pickens, AL1.0300$50,000
May 68:25 AM CDTEF1Lawrence, AL3.275$250,000
May 68:31 AM CDTEF1Pickens, AL1.3100$50,000
May 68:42 AM CDTEF0Morgan, AL0.775$50,000
May 68:48 AM CDTEF1Tuscaloosa, AL0.5100$65,000
May 68:57 AM CDTEF1Tuscaloosa, AL0.2100$100,000
May 68:59 AM CDTEF2Limestone, AL10.975$1.0 million
May 69:11 AM CDTEF0Walker, AL3.4200$850,000
May 69:20 AM CDTEF1Walker, AL1.0300$260,000
May 69:24 AM CDTEF0Walker, AL0.275$25,000
May 69:45 AM CDTEF0Blount, AL0.130$2,000
May 69:50 AM CDTEF1Jefferson, AL0.450$50,000
May 66:15 PM PDTEF0Wallowa, OR0.210$100,000
May 610:25 PM EDTEF0Carroll, VA1.520$10,000
May 68:28 PM PDTEF1Lincoln, WA3.430$30,000

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.