Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 201001
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
300 AM PDT MON OCT 20 2014

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...A DEEP UPPER TROUGH OFF
THE WEST COAST WILL GRADUALLY SHIFT INTO THE REGION TODAY. ENERGY IS
STILL DROPPING SOUTH ON THE WEST SIDE OF THE TROUGH, THUS THE
EASTWARD PROGRESSION WILL BE SLOW. A COLD FRONT ASSOCIATED WITH
THIS TROUGH WILL SLOWLY MOVE ACROSS WESTERN OREGON AND WASHINGTON
THIS MORNING. THE FRONT WILL THEN MOVE ACROSS THE CASCADES THIS
AFTERNOON, THEN OUT OF THE INTERIOR NORTHWEST THIS EVENING. PRECIP
ASSOCIATED WITH THIS SYSTEM WILL ALSO GRADUALLY WORK EAST ACROSS THE
INTERIOR NORTHWEST TODAY AND THIS EVENING. BEST PRECIP CHANCES WILL
BE OVER CENTRAL AND NORTH CENTRAL OREGON, AND SOUTH CENTRAL
WASHINGTON TODAY. THE BEST CHANCES WILL THEN SHIFT INTO OUR EASTERN
ZONES THIS EVENING. A SECONDARY WAVE WILL KEEP DECENT PRECIP CHANCES
GOING OVER THE BLUE MOUNTAINS EAST THROUGH WALLOWA COUNTY AND SOUTH
INTO GRANT COUNTY OVERNIGHT. SNOW LEVELS WILL LOWER THIS AFTERNOON
AND TONIGHT, BUT WILL RANGE FROM NEAR 6500 FEET OVER THE CASCADES TO
NEAR 8000 FEET OVER WALLOWA COUNTY OVERNIGHT. SNOW LEVELS BY
DAYBREAK TUESDAY WILL RUN BETWEEN 6000 AND 6500 FEET AREAWIDE. THUS
ANY SIGNIFICANT SNOWS WILL BE OVER THE HIGHEST MOUNTAINS. MAY SEE
SOME LOCALLY BREEZY WINDS TODAY WITH AND BEHIND THE COLD FRONT. A
STRAY THUNDERSTORM MAY BE POSSIBLE OVER GRANT COUNTY THIS EVENING.
PRECIPITATION WILL CONTINUE OVER EXTREME NORTHEAST OREGON ON
TUESDAY, THOUGH IT WILL GRADUALLY DECREASE THROUGH THE DAY AND END
BY LATE AFTERNOON. ANOTHER SYSTEM WILL BEGIN TO SPREAD PRECIP INTO
OUR WESTERN MOST ZONES LATE TUESDAY AND TUESDAY NIGHT. 90

.LONG TERM...WEDNESDAY THROUGH MONDAY...A LONGWAVE MID/UPPER LEVEL
LOW PRESSURE SYSTEM IN THE GULF OF ALASKA SOUTHWARD TO NEARLY 30N
WILL AIM A LARGE PINEAPPLE EXPRESS SUB-TROPICAL MOISTURE PLUME
ASSOCIATED WITH A COLD FRONT INTO THE PACIFIC NORTHWEST ON
WEDNESDAY. THE FRONT WILL REACH THE WASHINGTON CASCADES BY DAYBREAK
ON WEDNESDAY WITH CATEGORICAL RAIN ALONG THE EAST SLOPES OF THE
WASHINGTON CASCADES THROUGHOUT THE DAY ON WEDNESDAY. HOWEVER,
CENTRAL AND NORTHCENTRAL OREGON WILL BE IN A RAIN SHADOWING SCENARIO
ON WEDNESDAY DUE TO DOWNSLOPE WINDS OFF THE OREGON CASCADES. THE
FRONT MOVES EAST OF THE CASCADES WEDNESDAY NIGHT FOR RAIN LIKELY.
THURSDAY THE FRONT REMAINS QUASI-STATIONARY FOR WIDESPREAD RAIN. ON
FRIDAY THROUGH THE WEEKEND THE LOW IN THE GULF OF ALASKA MORPHS INTO
A TROUGH THAT DIGS SOUTHEAST TOWARD THE COAST THUS SEND FRESH
MOISTURE AND RAIN INTO THE REGION.  POLAN

&&

.AVIATION...12Z TAFS...MVFR CEILINGS AND VSBY ARE POSSIBLE AT TAF
SITES KYKM AND KALW IN PATCHY FOG UNTIL 15Z. OTHERWISE MOSTLY VFR
CONDITIONS ARE LIKELY UNTIL CLOUDS AND SOME SHOWERS WORK THERE WAY
INTO TAF SITE KDLS...KRDM...KBDN...KYKM AFTER 15Z THAT COULD PRODUCE
LCL MVFR CONDITIONS. THE MVFR CONDITIONS MAY AFFECT THE REMAINDER OF
THE TAF SITE AFTER 18Z.  POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  68  46  62  43 /  20  60  30  10
ALW  68  49  63  47 /  10  60  30  10
PSC  68  49  67  45 /  20  50  10  10
YKM  61  42  62  43 /  40  30  10  30
HRI  67  46  66  42 /  20  50  20  10
ELN  65  43  62  43 /  50  40  10  50
RDM  62  35  59  39 /  60  50  10  10
LGD  73  44  59  38 /  10  60  50  10
GCD  68  41  58  39 /  20  60  20  10
DLS  66  47  65  45 /  60  40  20  30

&&

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

FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT...
WWW.WEATHER.GOV/PENDLETON

$$

90/99/99







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