Flash Flood in Oregon, June 28, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OREGON
215 PM PDT MON JUN 28 2004

.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...LATEST WATER VAPOR
IMAGERY SHOWS MOISTURE STREAMING NORTHWARD ACROSS THE REGION AS A
CUTOFF LOW ALONG THE BC COAST IS BEGINNING TO RETROGRADE...AND A
TROUGH OF LOW PRESSURE ACROSS CA/NV NUDGES NORTHWARD. WAVES IN
BETWEEN THESE TWO LARGE SCALE SYSTEMS ARE MOVING N/NE ACROSS EASTERN
WA/OR...PRODUCING SCT TSTMS ACROSS THE NE OREGON MTNS. STEERING
WINDS ARE VERY LIGHT...THUS THE STRONGER STORMS ARE PRODUCING
LOCALLY HEAVY RAINFALL...WITH RADAR ESTIMATES OVER AN INCH PER
HOUR...AND REPORTS AS HIGH AS ONE INCH PER HOUR.

TNGT/TUE...ONE WAVE WILL MOVE ACROSS NE OR/SE WA THIS EVENING...WITH
ANOTHER MORE POTENT WAVE CURRENTLY MOVING NORTH ACROSS NEVADA
ENTERING EASTERN OR BY TUE AM. MOISTURE AND INSTABILITY...AS WELL AS
UPPER DIVERGENCE REMAIN ACROSS THE AREA...THUS WILL KEEP SCT
CONVECTION IN THE FCST FOR THE EAST. STEERING WINDS REMAIN VERY
WEAK...THUS LOCALLY HEAVY RAIN REMAINS A THREAT...WITH PERHAPS A
BREAK FROM HEAVY RAIN BY LATE EVENING BETWEEN WAVES. WILL CONTINUE
THE URBAN AND SMALL STREAM FLOOD ADVISORY THROUGH 9 PM TONIGHT FOR
THE EASTERN MTNS OF OR. WITH FLOW BECOMING MORE SOUTHERLY...VERSUS
SW MON/MON NIGHT...THINK CONVECTION WILL MAKE SOME MOVE TO THE
WEST...INCLUDING THE COL BASIN/BLUE MTN FOOTHILLS WITH AT LEAST
ISOLATED AFTN STORMS. WILL INCLUDE LOCALLY HEAVY RAIN WORDING FOR
THE EASTERN MTNS TUE AFTN/EVE.

WED...STEERING WINDS BEGIN TO INCREASE A BIT...SO THINK HEAVY RAIN
THREAT WILL DIMINISH SOME...AS WILL COVERAGE AS A TROUGH APPROACHING
THE WEST COAST WILL MAKE THE FLOW MORE WESTERLY. GFS DOES DEPICT A
SIG WAVE MOVING NORTHWARD TO CENTRAL OR...BUT THINK THIS COULD BE
SUSPECT...AS PROGGED INTENSITIES LOOK TOO STRONG.

.LONG TERM...THURSDAY THROUGH MONDAY...THURSDAY THROUGH MONDAY...AN
UPPER TROUGH THAT IS ALONG THE CALIFORNIA COAST WILL REMAIN THERE
THROUGH FRIDAY NIGHT.  THIS WILL KEEP A MOIST AND UNSTABLE DEEP
SOUTHERLY FLOW ALOFT OVER THE FORECAST AREA.  AS A RESULT CAN EXPECT
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS TO OCCUR EACH DAY
THROUGH FRIDAY NIGHT.  THE UPPER TROUGH WILL THEN WEAKEN AND FILL
LATER ON SATURDAY INTO SUNDAY WITH THE FORECAST AREA BECOMING UNDER
A NORTHWEST FLOW ALOFT.  THIS WILL CAUSE THE ATMOSPHERE OVER THE
PACIFIC NORTHWEST TO DRY OUT AND BECOME MORE STABLE.  AS SUCH THE
AFTERNOON AND EVENING CONVECTIVE ACTIVITY WILL END WITH THE ONLY
CHANCE OF ANY SHOWERS OVER THE HIGHER MOUNTAINS OF EASTERN OREGON.
WILL ALSO SEE A CONSIDERABLE TEMPERATURE COOL DOWN FOR SUNDAY AND
MONDAY BACK TO NEAR NORMAL READINGS.

&&

.PRELIMINARY POINT TEMPS/POPS...
PENDLETON (AIRPORT) 59 91 60 91 / 10 20 20 20
WALLA WALLA         61 91 62 91 / 10 20 20 20
TRI-CITIES          58 94 59 93 / 05 20 20 10
YAKIMA              56 91 58 92 / 00 10 05 10
&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...URBAN AND SMALL STREAM FLOOD ADVISORY THROUGH 9 PM TONIGHT
     FOR UNION...GRANT...AND WALLOWA COUNTIES.
WA...NONE.
&&

89/88

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OREGON
250 PM PDT MON JUN 28 2004

ORZ041>050-WAZ024>030-291200-
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-
250 PM PDT MON JUN 28 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 WITH LOCALLY HEAVY RAIN
     BLUE MOUNTAINS, JOHN DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS,
     GRANDE RONDE VALLEY, WALLOWA COUNTY

THUNDERSTORMS
     NORTHWEST BLUE MOUNTAINS, CENTRAL OREGON

A MOIST SOUTH TO SOUTHWESTERLY FLOW ALOFT WILL USHER IN PLENTY OF
MID LEVEL MOISTURE AND INSTABILITY TODAY AND TONIGHT.  ISOLATED TO
SCATTERED COVERAGE OF THUNDERSTORMS ARE EXPECTED TO DEVELOP...MAINLY
DURING THE AFTERNOON AND EVENING HOURS.  THESE THUNDERSTORMS WILL BE
IN A WEAK STEERING FLOW ENVIRONMENT.  THIS WILL RESULT IN LOCALLY
HEAVY RAINS FROM SLOW MOVING THUNDERSTORMS. AN URBAN AND SMALL
STREAM FLOOD ADVISORY HAS BEEN ISSUED. REFER TO AWIPS ID PDXFLSPDT
OR WMO HEADER RWUS42 KPDT FOR FURTHER DETAILS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SATURDAY

THUNDERSTORMS WITH LOCALLY HEAVY RAIN TUESDAY
          BLUE MOUNTAINS, JOHN DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS,
          GRANDE RONDE VALLEY, WALLOWA COUNTY

THUNDERSTORMS TUESDAY
          FOOTHILLS OF THE BLUE MOUNTAINS (WA), NORTHWEST BLUE
          MOUNTAINS, NORTH CENTRAL OREGON, CENTRAL OREGON, FOOTHILLS
          OF THE BLUE MOUNTAINS (OR)

THUNDERSTORMS WEDNESDAY
          FOOTHILLS OF THE BLUE MOUNTAINS (WA), NORTHWEST BLUE
          MOUNTAINS, 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

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

A SOUTH TO SOUTHWESTERLY FLOW ALOFT WILL CONTINUE TUESDAY THROUGH
THURSDAY...WITH CONVECTION A POSSIBILITY EACH DAY.  THE MAIN THREAT
FROM THESE STORMS WILL CONTINUE TO BE LOCALLY HEAVY RAIN..ESPECIALLY
TUESDAY AS STEERING WINDS REMAIN WEAK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED.

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