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.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PDT wrote it up.
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.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Pendleton, OR wrote its last area forecast discussion before the first event at May 6, 12:15 PM PST, 3 hours 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PENDLETON OR 115 PM PDT WED MAY 6 2009 .SHORT TERM...TONIGHT THROUGH SATURDAY...A TROUGH OF LOW PRESSURE CONTINUES TO MOVE INTO THE PACIFIC NORTHWEST THIS AFTERNOON. THE LOW CENTER IS CURRENTLY LOCATED BETWEEN 140 W AND 130 W. RADAR IMAGERY INDICATES THAT RAIN SHOWERS ARE INCREASING OVER THE REGION AGAIN AHEAD OF A COLD FRONT CURRENTLY OVER WESTERN OREGON AND WASHINGTON. THIS FRONT WILL MOVE EAST OF THE CASCADES LATER THIS AFTERNOON AND EVENING. WINDS WILL BE BREEZY AHEAD AND WITH THE COLD FRONT ACROSS CENTRAL OREGON AND PORTIONS OF THE COLUMBIA BASIN. SNOW LEVELS WILL LOWER BEHIND THE FRONT TO AROUND 4500-5000 FEET. NOT EXPECTING SIGNIFICANT SNOW ACCUMULATIONS AS THE BRUNT OF THE MOISTURE WILL BE AHEAD OF THE FRONT. THE TROUGH WILL CONTINUE OVER THE PACIFIC NORTHWEST ON THURSDAY AS THE LOW CENTER MOVES THROUGH NORTHERN WASHINGTON. WINDS WILL INCREASE AGAIN AND BE BREEZY TO WINDY ACROSS THE COLUMBIA BASIN AND SURROUNDING VALLEYS TOMORROW AFTERNOON. SHOWERS WILL BE POSSIBLE WITH THE DISTURBANCE THURSDAY...PARTICULARLY IN THE MOUNTAINS WITH UPSLOPE FLOW. BELIEVE THAT MOST OF THE COLD UNSTABLE AIR WILL REMAIN NORTH OF THE AREA...THEREFORE HAVE REMOVED THE SLIGHT CHANCE OF THUNDERSTORMS FROM WALLOWA COUNTY...THOUGH WOULD NOT RULE OUT THE POSSIBILITY OF A STRIKE OR TWO IN THE NORTHEAST PORTION OF THE COUNTY. THE REGION WILL GRADUALLY BEGIN TO DRY OUT ON FRIDAY AND SATURDAY AS A WEAK RIDGE OF HIGH PRESSURE BUILDS INTO THE AREA. TEMPERATURES WILL WARM AT THE END OF THE WEEK WITH THE LOWER ELEVATIONS APPROACHING THE 70S BY SATURDAY. DMH .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. THERE WILL BE A WEAK RIDGE OF HIGH PRESSURE BUILD INTO THE REGION SATURDAY NIGHT AND SUNDAY AS A STRONG LOW PRESSURE SYSTEM APPROACHES THE PACIFIC NORTHWEST. THE LOW WILL TRACK ACROSS THE AREA MONDAY NIGHT THROUGH TUESDAY. THERE IS STILL SOME VARIABILITY IN THE TRACK OF THE LOW...BUT STILL SHOULD BRING COOLER TEMPERATURES AND A CHANCE OF PRECIPITATION ACROSS THE REGION. THE TROUGH REMAINS OVER THE REGION THROUGH MIDWEEK WITH ADDITIONAL LOBES OF ENERGY TO MOVE THROUGH WITH TEMPERATURES REMAINING BELOW NORMAL. ML && .AVIATION...00Z TAFS...SCATTERED SHOWERS WILL PERSIST OVER THE REGION THROUGH THE NEXT 12 HOURS WITH SOME BRIEF PERIODS OF MVFR CEILING AS THE HEAVIER SHOWERS MOVE THROUGH. SHOWER ACTIVITY SHOULD BE ENDING AFTER 03Z WITH WINDS INCREASING FROM THE WEST TO SOUTHWEST 10 TO 20 MPH. ML && .HYDROLOGY...SEVERAL RIVERS ACROSS THE AREA CONTINUE TO RUN AT BANKFULL LEVELS. THE LIGHT PRECIPITATION AMOUNTS ARE NOT EXPECTED TO CAUSE THEM TO RISE ABOVE FLOOD STAGE WITH MOST CRESTING BY LATE THURSDAY AND THEN RECEDING AS DRIER CONDITIONS PREVAIL OVER THE NEXT SEVERAL DAYS. ML && .PRELIMINARY POINT TEMPS/POPS... PDT 44 57 38 61 / 30 30 10 0 ALW 46 58 42 63 / 30 30 10 0 PSC 46 64 39 67 / 20 20 10 0 YKM 38 59 34 64 / 20 20 10 0 HRI 44 63 38 65 / 20 20 10 0 ELN 40 58 37 62 / 20 20 10 0 RDM 33 54 26 61 / 30 10 10 0 LGD 40 51 34 57 / 50 30 20 10 GCD 37 52 33 57 / 30 20 20 10 DLS 45 60 40 67 / 30 20 10 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. && TI:GGG FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT... WWW.WEATHER.GOV/PENDLETON 84/93/93/93
HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE PENDLETON OR
905 AM PDT WED MAY 6 2009
CORRECTED TODAY AND TONIGHT TO ADD LOW HAZARDS LINE
ORZ041>044-049-050-501>506-WAZ024-026>030-501-502-071200-
EASTERN COLUMBIA RIVER GORGE OF OREGON-NORTH CENTRAL OREGON-
CENTRAL OREGON-LOWER COLUMBIA BASIN OF OREGON-GRANDE RONDE VALLEY-
WALLOWA COUNTY-FOOTHILLS OF THE BLUE MOUNTAINS OF OREGON-
NORTHERN BLUE MOUNTAINS OF OREGON-
SOUTHERN BLUE MOUNTAINS OF OREGON-
NORTHERN WHEELER AND SOUTHERN GILLIAM COUNTIES-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-
EASTERN COLUMBIA RIVER GORGE OF WASHINGTON-KITTITAS VALLEY-
YAKIMA VALLEY-LOWER COLUMBIA BASIN OF WASHINGTON-
FOOTHILLS OF THE BLUE MOUNTAINS OF WASHINGTON-
NORTHWEST BLUE MOUNTAINS-
EAST SLOPES OF THE CENTRAL CASCADES OF WASHINGTON-
EAST SLOPES OF THE SOUTHERN CASCADES OF WASHINGTON-
905 AM PDT WED MAY 6 2009
THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.
.DAY ONE...TODAY AND TONIGHT
THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.
A TROUGH OF LOW PRESSURE WILL MOVE INTO THE PACIFIC NORTHWEST TODAY
SPREADING RAIN ACROSS THE REGION. THE ASSOCIATED COLD FRONT WILL
BRING COOLER AIR AND AN INCREASE IN WINDS THIS AFTERNOON AND
EVENING. THIS FRONT WILL HELP LOWER SNOW LEVELS TONIGHT WITH RAIN
AND SNOW SHOWERS POSSIBLE IN THE HIGHER TERRAIN OVERNIGHT.
ACCUMULATIONS ARE EXPECTED TO BE LIGHT AS MOST OF THE HEAVIER
PRECIPITATION WILL BE AHEAD OF THE FRONT.
.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY
THUNDERSTORMS THURSDAY
NORTHWEST BLUE MOUNTAINS, GRANDE RONDE VALLEY, WALLOWA COUNTY,
NORTHERN BLUE MOUNTAINS OF OREGON
SOME ATMOSPHERIC INSTABILITY ON THURSDAY AFTERNOON AND EVENING MAY
RESULT IN ISOLATED THUNDERSTORMS AGAIN OVER THE NORTHEAST MOUNTAINS.
ANY STORMS THAT DO FORM ARE EXPECTED TO BE WEAKER THAN ON WEDNESDAY
WITH LESS COVERAGE AND FREQUENCY. HIGHER PRESSURE ALOFT WILL BUILD
OVER THE REGION BEGINNING FRIDAY WITH A WARMING AND DRYING TREND
THAT WILL CONTINUE THROUGH MOST OF THE WEEKEND.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE REQUIRED.
WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:
WWW.WRH.NOAA.GOV/PDT/CURRENTHAZARDS/HWO.HTML
ALL LETTERS IN THE ABOVE URL ARE LOWER CASE...EXCEPT THE H IN
CURRENTHAZARDS.The Pendleton radar (KPDT), 6 km away, was scanning. The volume nearest the first event began at 23:45 UTC.
2 tornado, 2 hail, 1 thunderstorm wind. Local standard time, as filed.
Downed tree branches caused power outage. A 20 foot tall lilac bush was uprooted and shingles were torn off roofs.
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.
Hail up to golf ball size punched holes in vinyl siding.
Penny to nickel sized hail covered ground on Highway 11 at milepost 14.
Eyewitnesses saw the cover being ripped off the sewer ponds and rotating debris being blown into the air across the Wallowa Rover.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2009Every state in 2009This day in weather historyThe tornado archive for Oregon, 2009Warnings in Oregon, May 2009
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 162720, 162727, 162743, 162721, 162738.