Severe Thunderstorm Warning 19, NWS Pendleton, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OREGON
928 AM PDT MON JUL 19 2004

.SHORT TERM...TODAY THROUGH WEDNESDAY...A BAND OF SHOWERS AND
THUNDERSTORMS IS MOVING NORTH THROUGH THE KITTITAS AND YAKIMA
VALLEYS THIS MORNING WITH A SECOND BAND OF THUNDERSTORMS MOVING
ACROSS THE BLUE MOUNTAINS. THESE CONVECTIVE BANDS WILL MOVE OUT OF
FORECAST AREA BY AROUND 1100 AM. FLOW ALOFT WILL CONTINUE FROM THE
SOUTH TODAY THUS BRINGING ADDITIONAL MID LEVEL MOISTURE INTO THE
AREA. WITH DAYTIME SURFACE HEATING AND A BREAK IN CLOUD COVER THIS
MORNING OVER MOST OF EASTERN OREGON EXPECT THE ATMOSPHERE OVER
CENTRAL AND NORTHEAST OREGON TO DESTABILIZE THIS AFTERNOON. COOLER
MARINE AIR WILL FILTER THROUGH THE CASCADE PASSES AND THE COLUMBIA
RIVER GORGE TODAY TO CREATE BREEZY CONDITIONS MAINLY IN THE KITTITAS
VALLEY AND THE EASTERN COLUMBIA RIVER GORGE. SATELLITE IMAGERY SHOWS
AN UPPER LEVEL SHORT WAVE MOVING NORTHEAST ALONG THE NORTHERN
CALIFORNIA COAST. THIS DISTURBANCE WILL MOVE INTO CENTRAL OREGON
THIS AFTERNOON AND WILL ACT TO TRIGGER CONVECTION IN CENTRAL OREGON.
ANOTHER STRONGER SHORT WAVE WILL MOVE ACROSS THE REGION TONIGHT AND
TUESDAY MORNING. THESE TWO SYSTEMS WILL KEEP A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS IN THE BLUE MOUNTAINS TONIGHT INTO TUESDAY
MORNING. ON TUESDAY THE FLOW ALOFT WILL BECOME WESTERLY AND THE AIR
MASS WILL BE DRIER AND MORE STABLE OVER MOST OF THE FORECAST AREA.
THUS TUESDAY WILL BE DRY IN MOST AREAS...EXCEPT FOR A SLIGHT CHANCE
OF SHOWERS AND THUNDERSTORM IN WALLOWA COUNTY. THE FLOW ALOFT WILL
REMAIN WESTERLY TUESDAY NIGHT AND WEDNESDAY WITH SLIGHTLY COOLER
MARINE AIR MOVING INLAND FROM THE NORTHEAST PACIFIC FOR DRY AND
STABLE CONDITIONS EAST OF THE CASCADES TUESDAY NIGHT AND WEDNESDAY.
POLAN

.LONG TERM...WEDNESDAY NIGHT THROUGH FRIDAY...THE PACIFIC NORTHWEST
WILL BE UNDER A WEAK NORTHERLY TO NORTHWESTERLY FLOW AS A RIDGE OF
HIGH PRESSURE STRENGTHENS OFF THE COAST. THIS IS A DRY PATTERN FOR
THE REGION...AND TEMPERATURES WILL BE NEAR TO A LITTLE ABOVE NORMAL
WITH PLENTY OF SUNSHINE. SATURDAY AND SUNDAY...THE FLOW TURNS MORE
FROM THE WEST AS THE RIDGE SHIFTS EASTWARD. TEMPERATURES WILL WARM
AGAIN...WITH SOME LOCATIONS IN THE BASIN EXPECTED TO REACH THE
TRIPLE DIGITS ONCE AGAIN. RAINFALL CHANCES WILL BE MINIMAL...
ALTHOUGH GREATER INSTABILITY VALUES ASSOCIATED WITH A SOUTHWESTERLY
FLOW COULD PRODUCE SOME CONVECTIVE ACTIVITY OVER CENTRAL OREGON BY
SUNDAY. OVERALL...CHANGES TO THE GOING FORECAST WERE MINOR AS MODELS
HAVE HAD A HARD TIME GRASPING EXACTLY WHEN AND HOW FAR EAST THE
RIDGE WILL MIGRATE. WILL WAIT FOR BETTER RUN TO RUN CONSISTENCY
BEFORE MAKING SIGNIFICANT CHANGES.  JWM

&&

.PRELIMINARY POINT TEMPS/POPS...
PENDLETON (AIRPORT) 088 060 086 / 020 020 005
WALLA WALLA         091 062 087 / 020 020 005
TRI-CITIES          093 058 089 / 010 010 005
YAKIMA              089 057 084 / 010 010 005
HERMISTON           092 058 088 / 010 010 005
ELLENSBURG          083 057 078 / 010 010 010
REDMOND             085 048 084 / 010 010 010
LA GRANDE           090 054 083 / 020 020 010
JOHN DAY            090 055 083 / 020 020 010
THE DALLES          087 062 083 / 010 010 005
&&

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

99

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OREGON
512 AM PDT MON JUL 19 2004

ORZ041>050-WAZ024>030-201200-
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-
512 AM PDT MON JUL 19 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
     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, EASTERN COLUMBIA RIVER GORGE (OR), 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

WIDESPREAD INSTABILITY...ABUNDANT LOW TO MID LEVEL MOISTURE AND A
WEATHER DISTURBANCE WILL CAUSE ISOLATED TO SCATTERED THUNDERSTORMS
TODAY...MAINLY OVER THE EASTERN MOUNTAINS AND ALONG THE CASCADES
CREST AND EAST SLOPES.  THESE STORMS WILL PRODUCE FREQUENT
LIGHTNING...BRIEF HEAVY RAIN AND POSSIBLE GUSTY WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

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

LINGERING MOISTURE AND INSTABILITY WILL ALLOW FOR ISOLATED
THUNDERSTORMS IN THE NORTHEAST OREGON AND SOUTHEAST WASHINGTON
MOUNTAINS ON TUESDAY.  AFTER TUESDAY DRY AND STABLE AIR WILL MOVE
INTO THE REGION WITH BUILDING HIGH PRESSURE AND WARMING TEMPERATURES
AGAIN.

.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.