Hail in Oregon, August 19, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OREGON
207 PM PDT THU AUG 19 2004

.SHORT TERM...THURSDAY NIGHT THROUGH SATURDAY NIGHT...WEAK MID LEVEL
LOW PRESSURE SYSTEM IS MOVING ACROSS OREGON ACCOMPANIED BY
RELATIVELY HIGH LOW LEVEL MOISTURE.  THE MID LEVEL LOW IS NOT BEING
HANDLED VERY WELL BY THE MODELS.  THEY HAVE THE ENERGY 100 MILES
FURTHER TO THE SOUTH AND WEST.  THE FORECAST WAS MODIFIED BASED UPON
THIS DIFFERENCE. THE WEAK UPPER FLOW ACCOMPANIED WITH THE
INSTABILITY AND HIGH LOW LEVEL MOISTURE REALLY MAKES THE CENTRAL AND
EASTERN MOUNTAINS AREA VERY PRIME FOR SOME POSSIBLE FLASH FLOODS. AS
THE UPPER DISTURBANCE CONTINUES TO MOVE TO THE EAST...THE
THUNDERSTORMS TOMORROW SHOULD BE IN THE VERY SOUTHERN PART OF THE
CENTRAL MOUNTAINS AND OVER THE WALLOWAS. THE TEMPS WILL STAY FAIRLY
WARM TOMORROW...BUT THEN WILL START TO FALL ON SATURDAY AS THE RIDGE
BREAKS DOWN AND A COLD APPROACHES THE AREA. JACOBSON

.LONG TERM...SUNDAY THROUGH THURSDAY...NEW GFS RUN IS MUCH WEAKER
WITH THE COMING TROUGH THAN THE PREVIOUS RUN AND IS NOW LOOKING
MUCH MORE REASONABLE AND IN LINE WITH THE OTHER LONG RANGE MODELS.
A BIG CHANGE IS STILL FORECAST TO BEGIN BY SUNDAY. AN UPPER TROUGH
WILL MOVE INTO THE PACIFIC NORTHWEST WITH COOLER MARINE AIR BEHIND
IT. AHEAD OF IT (ON SATURDAY) WILL BE MOIST...VERY WARM AND UNSTABLE
AIR. AS THE COOLER MARINE AIR PUSHES INTO THE WARM AND UNSTABLE AIR
IT WILL PRODUCE SHOWERS AND THUNDERSTORMS WHICH WILL CONTINUE INTO
SUNDAY. ON SUNDAY COOLER AIR ALOFT WILL ALSO MOVE OVER THE FORECAST
AREA AND CAUSE THE ATMOSPHERE TO BECOME MORE UNSTABLE. BY THAT TIME
THE LOWER LEVELS WILL ALSO HAVE MOISTENED UP. THE RESULT WILL BE A
COOLER AND SHOWERY DAY...WITH POSSIBLE AFTERNOON THUNDERSTORMS. THIS
SCENARIO WILL CONTINUE INTO EARLY NEXT WEEK THROUGH TUESDAY. BY
WEDNESDAY THE SHOWER AND THUNDERSTORM ACTIVITY WILL DECREASE AS THE
MORE STABLE BACK SIDE OF THE TROUGH MOVES OVER THE FORECAST AREA
WITH A NORTHWEST FLOW ALOFT. ANY LEFT OVER SHOWERS OR THUNDERSTORMS
WILL BE OVER THE EASTERN AND NORTHEAST MOUNTAINS. TEMPERATURES WILL
BEGIN TO WARM UP AT THAT TIME AS WELL...BUT VERY SLOWLY. RSC.

&&

.PRELIMINARY POINT TEMPS/POPS...
PENDLETON (AIRPORT) 066 092 064 090 / 005 000 000 005
WALLA WALLA         068 095 065 091 / 010 000 000 005
TRI-CITIES          063 097 062 093 / 005 000 000 005
YAKIMA              060 095 059 090 / 020 000 000 005
HERMISTON           064 096 062 092 / 005 000 000 005
ELLENSBURG          061 091 059 088 / 020 000 005 010
REDMOND             054 091 050 087 / 020 000 005 005
LA GRANDE           056 091 054 090 / 030 020 000 010
JOHN DAY            058 094 057 091 / 030 010 005 010
THE DALLES          065 093 064 089 / 005 000 005 010
&&

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

77

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE PENDLETON OREGON
940 AM PDT THU AUG 19 2004

CORRECTED TO MENTION FLOOD WATCH FOR FLASH FLOODING IN TEXT WORDING

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-
940 AM PDT THU AUG 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

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

THUNDERSTORMS
     EAST SLOPES OF THE SOUTHERN CASCADES, CENTRAL OREGON, BLUE
     MOUNTAINS (WA)

LOW PRESSURE WILL MOVE INTO THE PACIFIC NORTHWEST AND COMBINE WITH
LOW LEVEL MOISTURE TO PRODUCE ISOLATED THUNDERSTORMS ACROSS PORTIONS
OF THE AREA. SLOW MOVING THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON AND EVENING...WHICH WILL LIKELY RESULT IN FLASH FLOODING
NEAR THUNDERSTORMS. A FLOOD WATCH FOR FLASH FLOODING IS IN EFFECT
FOR THIS AFTERNOON AND EVENING FOR PORTIONS OF THE AREA.  PLEASE SEE
PRODUCT PDXFFAPDT FOR DETAILS. SOME OF THE STORMS MAY BECOME STRONG
PRIMARILY EAST OF A LINE FROM SISTERS OREGON TO PILOT ROCK TO DAYTON
WASHINGTON. ALSO THE EAST SLOPES OF THE WASHINGTON CASCADES MAY
RECEIVE ISOLATED STRONG THUNDERSTORMS. THE STRONG STORMS MAY CONTAIN
HAIL...HEAVY RAIN...AND FREQUENT LIGHTNING. ALTHOUGH BRIEF GUSTY
WINDS TO 45 MPH ARE POSSIBLE.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THUNDERSTORMS FRIDAY
          JOHN DAY BASIN, OCHOCO-JOHN DAY HIGHLANDS, GRANDE RONDE
          VALLEY, WALLOWA COUNTY

THUNDERSTORMS SUNDAY
          EAST SLOPES OF THE SOUTHERN CASCADES, JOHN DAY BASIN,
          OCHOCO-JOHN DAY HIGHLANDS

FOR FRIDAY MOISTURE WILL LINGER ACROSS PORTIONS OF THE AREA AND WILL
COMBINE WITH DAYTIME HEATING TO PRODUCE ISOLATED THUNDERSTORMS
MAINLY OVER THE JOHN DAY BASIN...BLUE AND WALLOWA MOUNTAINS.

BY SUNDAY A COLD FRONT WILL MOVE ACROSS THE AREA. THIS WILL HELP TO
PRODUCE SCATTERED THUNDERSTORMS OVER THE EAST SLOPES OF THE
WASHINGTON CASCADES AND THE JOHN DAY BASIN.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS LIKELY THIS AFTERNOON AND EVENING FOR FLASH
FLOODING.

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.