Severe Thunderstorm Warning 28, NWS Pendleton, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OREGON
150 PM PDT SAT JUL 24 2004

.SHORT TERM...TONIGHT THROUGH TUESDAY...SUBSIDENCE FROM AN UPPER
LEVEL RIDGE HAS FORMED A THERMAL TROUGH OVER EASTERN WASHINGTON AND
OREGON. THE THERMAL TROUGH WILL REMAIN OVER THE AREA TONIGHT WITH
RELATIVELY WARM TEMPERATURES WITH POOR RELATIVE HUMIDITY RECOVERIES
SPREADING TO THE NORTHEAST MOUNTAINS. A RED FLAG WARNING WILL
CONTINUE FOR LOW RH AND POOR NIGHTTIME RECOVERY THROUGH THIS EVENING
ALONG THE CASCADES AND EAST SLOPES. A RED FLAG WARNING FOR CENTRAL
OREGON TO THE BAKER COUNTY INCLUDING THE OCHOCO HIGHLANDS WILL
CONTINUE THROUGH SUNDAY.

TONIGHT THE RIDGE WILL MOVE EAST. TONIGHT AND SUNDAY A COUPLE OF
WEAK DISTURBANCES WILL MOVE UP THE BACKSIDE OF THE RIDGE. MID
LEVEL MOISTURE AND INSTABILITY ASSOCIATED WITH THESE DISTURBANCES
WILL TRIGGER ELEVATED CONVECTION FROM SOUTHERN DESCHUTES COUNTY TO
THE NORTHEAST OREGON MOUNTAINS.

THE THERMAL TROUGH WILL MOVE EAST WITH THE RIDGE. A PUSH OF MARINE
AIR WILL BEGIN TO SEEP THROUGH THE CASCADES TONIGHT...COOLING MANY
AREAS NEAR THE CASCADES A FEW DEGREES. IT WILL ALSO INCREASE THE
RELATIVE HUMIDITY ALONG THE CASCADES. IN THE REST OF THE AREA
TEMPERATURES WILL REMAIN ABOVE NORMAL SUNDAY. WINDS WILL PICK UP
ESPECIALLY IN THE COLUMBIA RIVER GORGE AND KITTITAS VALLEYS DURING
THE DAY SUNDAY AND OVERNIGHT INTO MONDAY. AS THIS MARINE AIR SPREADS
OVER THE REST OF THE AREA THE ATMOSPHERE WILL BECOME MORE
STABLE AND CUT OFF THE THREAT OF THUNDERSTORMS OVER THE MOUNTAINS
SUNDAY EVENING.

MONDAY AND TUESDAY AN UPPER LEVEL RIDGE WILL BUILD OFFSHORE. THE
PACIFIC NORTHWEST WILL REMAIN IN STABLE NORTHWEST FLOW ALOFT. A WEAK
DISTURBANCE WILL MOVE DOWN THE RIDGE TUESDAY AND INCREASE CLOUD
COVER...BUT MOST OF THE ENERGY WILL REMAIN TO THE NORTH OF OUR AREA
SO I DO NOT EXPECT ANY PRECIPITATION WITH THE DISTURBANCE. COONFIELD

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...THE MODELS ARE IN
PRETTY GOOD AGREEMENT STARTING THE PERIOD OFF WITH NORTHWEST FLOW
AND ANOTHER RIDGE BUILDING AT ABOUT 130 WEST. THE ECMWF HAS A
FLATTER RIDGE AND IS QUICKER ON BRINGING IN THE NEXT SHORT WAVE ON
FRIDAY RATHER THAN SATURDAY. BOTH THE GFS AND ECMWF HAVE A LOW
FORMING OFF OF THE PACIFIC NORTHWEST ON SATURDAY MORNING. THE ECMWF
HAS THE LOW MUCH FURTHER TO THE NORTH OFF THE OREGON COAST WHILE THE
LOW ON THE GFS IS LOCATED JUST WEST OF SAN FRANCISCO. THIS SHOULD
ALLOW FOR SOME HOT AND DRY CONDITIONS TO BUILD BACK UP OVER OUR AREA
AND BE FAVORABLE FOR SOME EXTREME FIRE WEATHER CONDITIONS TO RETURN
BY THE END OF THE WEEK.  JACOBSON

&&

.PRELIMINARY POINT TEMPS/POPS...
PENDLETON (AIRPORT) 066 099 064 092 / 005 005 005 000
WALLA WALLA         072 100 065 092 / 005 005 005 000
TRI-CITIES          065 102 062 095 / 000 000 000 000
YAKIMA              064 098 060 090 / 000 000 000 000
HERMISTON           064 100 060 094 / 005 000 000 000
ELLENSBURG          062 090 061 086 / 000 000 000 000
REDMOND             065 094 050 091 / 020 005 000 000
LA GRANDE           061 099 056 092 / 020 020 020 000
JOHN DAY            059 099 055 094 / 020 020 020 000
THE DALLES          068 092 066 089 / 005 000 000 000
&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FOR FIRE WEATHER ZONES 609 610 AND 611 (EAST
SLOPES OF THE CASCADES) THROUGH THIS EVENING. RED FLAG WARNING FOR
ZONES 630 632 AND 638 (CENTRAL OREGON TO THE BAKER COUNTY INCLUDING
THE OCHOCO HIGHLANDS) THIS AFTERNOON THROUGH SUNDAY AFTERNOON.
WA...RED FLAG WARNING FOR FIRE WEATHER ZONES 681 (EAST SLOPES OF THE
CASCADES) THROUGH THIS EVENING.

&&

76

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OREGON
515 PM PDT SAT JUL 24 2004

ORZ041>050-WAZ024>030-251200-
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-
507 PM PDT SAT JUL 24 2004

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

.DAY ONE...TODAY AND TONIGHT

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

RED FLAG WARNING
     BLUE MOUNTAINS, JOHN DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS

A WEAK WEATHER DISTURBANCE WILL USHER IN MID-LEVEL MOISTURE TO THE
OREGON PORTION OF THE REGION LATE THIS AFTERNOON AND OVERNIGHT
TONIGHT.  ENOUGH INSTABILITY WILL BE PRODUCED TO GENERATE ISOLATED
THUNDERSTORMS.  THE STORMS WILL CONTAIN GUSTY WINDS...LIGHTNING...
AND LITTLE PRECIPITATION.  BECAUSE SOME OF THE STORMS MAY BE DRY
ALONG WITH THE DRY AND WARM CONDITIONS FOUND CURRENTLY IN THE
HIGHLANDS...A RED FLAG WARNING IS IN EFFECT.  SEE THE LATEST RFWPDT
WWUS86 KPDT FOR DETAILS.

RED FLAG WARNING
     EAST SLOPES OF THE SOUTHERN WASHINGTON CASCADES, NORTH CENTRAL
     OREGON, CENTRAL OREGON

A THERMAL TROUGH MOVING EASTWARD ACROSS THE CASCADES INTO CENTRAL
WASHINGTON AND OREGON TODAY WILL MAKE FOR EXCESSIVELY WARM AND DRY
CONDITIONS.  AREAS ALONG THE CASCADE CREST AND DIRECTLY EAST
INCLUDING THE EAST SLOPES OF THE SOUTHERN WASHINGTON CASCADES AND
NORTH CENTRAL AND CENTRAL OREGON HAVE SEEN A PROLONGED PERIOD OF
VERY DRY AND WARM CONDITIONS.  WITH THE SITUATION IN THOSE AREAS
PEAKING TODAY A RED FLAG WARNING HAS BEEN ISSUED.  SEE THE LATEST
RFWPDT WWUS86 KPDT FOR DETAILS.

EXCESSIVE HEAT
     EASTERN COLUMBIA RIVER GORGE (WA), YAKIMA VALLEY, LOWER COLUMBIA
     BASIN (WA), FOOTHILLS OF THE BLUE MOUNTAINS (WA), EASTERN
     COLUMBIA RIVER GORGE (OR), LOWER COLUMBIA BASIN (OR), FOOTHILLS
     OF THE BLUE MOUNTAINS (OR)

BASIN LOCATIONS WILL SEE TEMPERATURES IN THE UPPER 90S TO AROUND 106
THIS AFTERNOON.  OUTDOOR ACTIVITIES SHOULD BE LIMITED THIS
AFTERNOON.  IF YOU MUST BE OUTSIDE SEEK SHADE...DRINK PLENTY OF
FLUIDS...AND AVOID STRENUOUS ACTIVITY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

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

A WEAK WEATHER DISTURBANCE USHERING MID-LEVEL MOISTURE TO THE REGION
WILL CONTINUE TO MOVE OVERHEAD SUNDAY.  AMBIENT WARM TEMPERATURES IN
THE HIGHLANDS...COMBINED WITH INSTABILITY GENERATED BY THE MOISTURE
INFLUX WILL SPARK CONVECTION IN CENTRAL AND NORTHEAST OREGON AND
SOUTHEAST WASHINGTON.  STORMS WILL CONTAIN GUSTY
WINDS...LIGHTNING...AND LITTLE PRECIPITATION.

RED FLAG WARNING SUNDAY
          NORTH CENTRAL OREGON, CENTRAL OREGON, BLUE MOUNTAINS, JOHN
          DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS

THIS IS A CONTINUATION AND OF THE RED FLAG WARNING MENTIONED ABOVE.
THE THERMAL TROUGH WILL PUSH EASTWARD AND THUNDERSTORM POTENTIAL
WILL INCREASE ON SUNDAY OVER THE EASTERN HIGHLANDS.  SEE THE LATEST
RFWPDT OR WWUS86 KPDT FOR THE DETAILS.

EXCESSIVE HEAT SUNDAY
          EASTERN COLUMBIA RIVER GORGE (WA), YAKIMA VALLEY, LOWER
          COLUMBIA BASIN (WA), FOOTHILLS OF THE BLUE MOUNTAINS (WA),
          EASTERN COLUMBIA RIVER GORGE (OR), LOWER COLUMBIA BASIN
          (OR), FOOTHILLS OF THE BLUE MOUNTAINS (OR)

VERY WARM AND DRY CONDITIONS WILL PERSIST THROUGH SUNDAY IN THE
LOWER COLUMBIA BASIN AND ADJACENT VALLEYS WITH MANY LOCATIONS
APPROACHING OR EXCEEDING 100 DEGREES.  AVOID STRENUOUS ACTIVITIES
DURING THE HEAT OF THE DAY AND KEEP WATCH ON THE ELDERLY AND OTHERS
WHO MAY BE AFFECTED MOST BY THIS HOT SPELL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED SATURDAY EVENING THROUGH SUNDAY
FOR THUNDERSTORMS IN CENTRAL AND NORTHEAST OREGON AS WELL AS THE
BLUE MOUNTAINS IN SOUTHEAST WASHINGTON.

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.