Flash Flood Warning 15, NWS Pendleton, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OREGON
224 PM PDT SUN AUG 15 2004

.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...UPPER RIDGE REMAINS
OVER THE WEST...WITH THE RIDGE AXIS GENERALLY OVER IDAHO. MAIN
MOISTURE PLUME HAS SHIFTED TO THE EASTERN HALF OF OREGON AND EASTERN
THIRD OF WASHINGTON. EXPECT ISOLATED TO LOCALLY SCATTERED COVERAGE
OF THUNDERSTORMS LATE THIS AFTERNOON AND EVENING WITHIN THIS PLUME.
STORMS SHOULD BE FOCUSED MAINLY OVER THE EAST-CENTRAL AND NORTHEAST
OREGON MOUNTAINS. PRECIPITABLE WATER IS WELL ABOVE SEASONAL SO
EXPECT WET CONDITIONS UNDER THE CORE OF ANY CELLS. THERE IS ALSO
ENOUGH LINGERING MOISTURE OVER THE CASCADE EAST SLOPES TO SUPPORT
SOME ISOLATED STORMS THERE INTO THE EVENING. CONDITIONS CHANGE
LITTLE MONDAY. THUS EXPECT A REPEAT OF AFTERNOON AND EVENING SHOWERS
AND THUNDERSTORMS OVER THE HIGHER TERRAIN OF THE CENTRAL AND
NORTHEAST OREGON MOUNTAINS AS WELL AS THE CASCADE EAST SLOPES. ON
TUESDAY A STRONGER WAVE ROTATING AROUND THE CUT OFF OVER THE PACIFIC
MAY SLIGHTLY FLATTEN THE RIDGE. THIS WOULD LEAD TO SOME DRYING AND
STABILIZING OF THE AIR MASS...THUS LIMITING THE THUNDERSTORM
CHANCES. AT THIS TIME WILL GO WITH CONSENSUS AND LIMIT THUNDERSTORMS
TO THE CREST OF THE CENTRAL OREGON CASCADES. GKH

.LONG TERM...WEDNESDAY THROUGH SUNDAY...RIDGING WILL STRENGTHEN
ACROSS THE REGION WEDNESDAY AND PREVAIL THROUGH AT LEAST THE END OF
THE WEEK. MEDIUM RANGE MODELS DIFFER A BIT BY THE WEEKEND ON HOW TO
WEAKEN/BREAKDOWN THE RIDGE...WITH THE ECMWF FLATTENING OUT THE RIDGE
THE MOST...ALTHOUGH LESS THAN IT WAS SHOWING ON YESTERDAYS RUN.
WILL KEEP A DRY/ABOVE NORMAL TEMPERATURE FCST THROUGH NEXT
WEEKEND...WITH PERHAPS A FEW MORE CLDS AND A SLIGHT COOLDOWN
BY NEXT SUNDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
PENDLETON (AIRPORT) 067 097 066 095 / 010 010 010 005
WALLA WALLA         070 098 069 096 / 010 010 010 005
TRI-CITIES          064 102 063 099 / 010 010 010 005
YAKIMA              060 098 059 095 / 010 010 010 005
HERMISTON           064 100 063 098 / 010 010 010 005
ELLENSBURG          062 096 061 093 / 020 010 010 005
REDMOND             053 093 052 092 / 020 020 020 010
LA GRANDE           058 095 057 093 / 020 020 020 005
JOHN DAY            056 097 055 095 / 020 020 020 010
THE DALLES          068 094 067 093 / 020 010 010 005
&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
&&

90

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PENDLETON OREGON
445 AM PDT SUN AUG 15 2004

ORZ041>050-WAZ024>030-161200-
NORTH CENTRAL OREGON-CENTRAL OREGON-LOWER COLUMBIA BASIN (OR)-
FOOTHILLS OF THE BLUE MOUNTAINS (OR)-BLUE MOUNTAINS-JOHN DAY BASIN-
OCHOCO-JOHN DAY HIGHLANDS-GRANDE RONDE VALLEY-WALLOWA COUNTY-
EASTERN COLUMBIA RIVER GORGE (WA)-
EAST SLOPES OF THE SOUTHERN CASCADES-KITTITAS VALLEY-YAKIMA VALLEY-
LOWER COLUMBIA BASIN (WA)-FOOTHILLS OF THE BLUE MOUNTAINS (WA)-
NORTHWEST BLUE MOUNTAINS-
445 AM PDT SUN AUG 15 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND NORTHEAST OREGON
AS WELL AS SOUTH CENTRAL AND SOUTHEAST WASHINGTON.

.DAY ONE...

THUNDERSTORMS
     EASTERN COLUMBIA RIVER GORGE (WA), EAST SLOPES OF THE SOUTHERN
     CASCADES, KITTITAS VALLEY, NORTHWEST BLUE MOUNTAINS, EASTERN
     COLUMBIA RIVER GORGE (OR), NORTH CENTRAL OREGON, CENTRAL OREGON,
     BLUE MOUNTAINS, JOHN DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS,
     GRANDE RONDE VALLEY, WALLOWA COUNTY

SOUTHERLY FLOW ALOFT CONTINUES TO FEED MOISTURE ACROSS EASTERN
OREGON AND WASHINGTON TODAY.  INSTABILITY WILL COMBINE WITH THIS
MOISTURE...RESULTING IN THE FORMATION OF AFTERNOON AND EVENING
THUNDERSTORMS ALONG THE EAST SLOPES OF THE CASCADES AND ACROSS
CENTRAL AND NORTHEAST OREGON.  THE MAJOR THREAT FROM THESE
THUNDERSTORMS WILL BE THE POTENTIAL FOR HEAVY RAIN AS WELL AS GUSTY
WINDS AND HAIL.

.DAYS TWO THROUGH SEVEN...

THUNDERSTORMS MONDAY
          NORTHWEST BLUE MOUNTAINS, CENTRAL OREGON, BLUE MOUNTAINS,
          JOHN DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS, GRANDE RONDE
          VALLEY, WALLOWA COUNTY

SOUTHERLY FLOW WILL CONTINUE TO FEED MOISTURE AND INSTABILITY ACROSS
EASTERN OREGON AND WASHINGTON FOR ONE MORE DAY...CONTINUING THE
THREAT OF AFTERNOON AND EVENING THUNDERSTORMS ACROSS CENTRAL AND
NORTHEAST OREGON FOR TOMORROW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED.

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

PROTOTYPE GRAPHICAL FORECASTS OF WEATHER HAZARDS OUT TO SEVEN DAYS
ARE DISPLAYED ON THE WORLD WIDE WEB AT:

WWW.WRH.NOAA.GOV/PENDLETON/FORECAST/HWOGRAPHICS/HWOGRAPHICS.PHP

ALL LETTERS IN THE ABOVE URL ARE LOWER CASE...EXCEPT THE G IN
HWOGRAPHICS AND THE G IN HWOGRAPHICS.PHP.