Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 242302 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
402 PM PDT FRI OCT 24 2014

UPDATED AVIATION DISCUSSION

.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...A WARM FRONT ASSOCIATED
WITH A DEVELOPING PACIFIC STORM WILL CONTINUE TO MOVE NORTH THROUGH
THE REGION THIS EVENING. THE PRECIP WILL CONTINUE TO END ACROSS OUR
SOUTHERN ZONES THIS AFTERNOON WHILE IT SPREADS NORTH INTO OUR
WASHINGTON ZONES. BY DAYBREAK SATURDAY PRECIP WILL BE VERY LIMITED.
THE PACIFIC STORM WILL MOVE INTO WESTERN WASHINGTON SATURDAY
AFTERNOON, THEN MOVE INTO SOUTHERN BRITISH COLUMBIA SATURDAY NIGHT.
AT THIS TIME THE MAIN IMPACT OF THIS SYSTEM WILL BE WINDS. STRONGEST
WINDS ARE EXPECTED OVER THE SOUTH END OF THE GRANDE RONDE VALLEY,
ACROSS CENTRAL OREGON, AND PORTIONS OF THE COLUMBIA BASIN. GRADIENTS
WILL TIGHTEN OVERNIGHT ACROSS THE SOUTHERN GRANDE RONDE VALLEY AND
DURING SATURDAY MORNING ACROSS CENTRAL OREGON. EXPECT GUSTY WINDS IN
THE 20 TO 35 MPH RANGE WITH GUSTS OF 45-50 MPH. THUS HAVE ISSUED
WIND ADVISORIES FOR THESE AREAS. WINDS WILL GUST ALONG THE BLUE
MOUNTAIN FOOTHILLS WITH THE PASSAGE OF THE COLD FRONT SATURDAY
EVENING. ALSO WINDS WILL BECOME PERSISTENT IN THE 25 TO 35 MPH RANGE
WITH GUSTS OF 45-50 MPH OVERNIGHT INTO SUNDAY MORNING OVER THE
FOOTHILLS AND LOWER BASIN. THUS HAVE ALSO ISSUED A WIND ADVISORY FOR
THESE AREAS AS WELL. THIS SYSTEM WILL ALSO BRING MORE PRECIP TO THE
AREA. SNOW LEVELS WILL FALL LATE SATURDAY NIGHT, RUNNING BETWEEN
4500 AND 5000 FT BY SUNDAY MORNING. SHOWERS WILL CONTINUE DURING
SUNDAY DUE TO A MOIST ONSHORE FLOW. THUS SOME LIGHT SNOW
ACCUMULATIONS WILL BE POSSIBLE AT HIGHER ELEVATIONS. THE SHOWERS
WILL GRADUALLY DECREASE SUNDAY NIGHT. 90

.LONG TERM...MONDAY THROUGH FRIDAY...OTHER THAN ISOLATED MOUNTAIN
SHOWERS...A DRY FORECAST IS IN STORE FOR MONDAY AS A WEAK TRANSITORY
RIDGE CROSSES THE AREA. THE RIDGE WILL FLATTEN CONSIDERABLY ON
TUESDAY AS THE REMNANTS OF TROPICAL STORM ANA BECOME ENTRAINED IN A
STRONG WESTERLY FLOW INTO THE REGION. AS A RESULT...MODERATE RAIN
CAN BE EXPECTED ON TUESDAY...AND THEN SCATTERED SHOWERS...MAINLY
OVER THE MOUNTAINS...ON WEDNESDAY. SNOW LEVELS DURING THIS TIME WILL
RANGE FROM 6000-8000 FEET AND WILL REMAIN HIGH THROUGH THE END OF
THE WEEK. HIGH PRESSURE WILL BEGIN TO REBUILD ON WEDNESDAY
NIGHT...BUT ONCE AGAIN...THE DETERMINISTIC MODELS ARE DIVERGING BY
DAY 7. THE GFS IS FARTHER NORTH AND EAST COMPARED TO THE ECMWF WITH
A LARGE UPPER LEVEL TROUGH IN THE EASTERN PACIFIC. DESPITE THE
DIFFERENCES IN THE MODELS...BOTH THE GFS AND ECMWF ARE ADVERTISING
SOUTHWESTERLY FLOW OVER THE AREA THURSDAY AND FRIDAY WITH ABOVE
NORMAL TEMPERATURES. THEY ALSO AGREE ON A CHANCE OF RAIN
THURSDAY...BUT WHILE THE GFS CONTINUES THE RAIN INTO FRIDAY...THE
ECMWF QUICKLY PULLS THE PACIFIC LOW NORTHEASTWARD AND DRIES OUT THE
LOCAL AREA.  COBB

&&

.AVIATION...00Z TAFS...FORECASTING CIGS AND VSBYS REMAINS A
CHALLENGE DUE TO THE COMPLEX WEATHER SYSTEM MOVING INLAND. RAIN WILL
DETERIORATE CONDITIONS FROM VFR TO MVFR AT KPDT...KALW...KDLS...KPSC
AND KYKM THIS EVENING. RAIN HAS MOVED NORTH OF KRDM AND KBDN. THERE
WILL BE CLEARING BEHIND THE SYSTEM TONIGHT THAT MAY RESULT IN PATCHY
FOG AND STRATUS CLOUDS. FORECAST SOUNDINGS SHOW RADIATIONAL FOG AT
KPSC BY SUNRISE SATURDAY. AN EASTERLY SURFACE GRADIENT THROUGH THE
COLUMBIA RIVER GORGE MAY RESULT IN LOW LEVEL UPSLOPE CREATING
STRATUS CLOUDS AT KDLS OVERNIGHT. A COLD FRONT WILL APPROACH THE
AREA TOMORROW AND CLOUDS WILL AGAIN INCREASE DURING THE AFTERNOON.
SOUTH TO SOUTHWEST WINDS WILL ALSO INCREASE SATURDAY
AFTERNOON...ESPECIALLY AT KBDN AND KRDM. STRONGER WINDS CAN BE
EXPECTED ACROSS THE COLUMBIA BASIN AFTER 26/00Z. 82

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  44  66  45  58 /  30  20  30  20
ALW  47  66  48  57 /  60  20  40  30
PSC  45  63  48  63 /  60  20  30  20
YKM  42  56  42  57 /  70  30  50  20
HRI  42  64  46  62 /  50  20  30  20
ELN  41  58  41  56 /  70  40  50  20
RDM  39  63  37  54 /  10  20  40  20
LGD  43  66  44  53 /  20  20  40  40
GCD  42  64  42  53 /  10  20  40  30
DLS  45  60  46  58 /  70  50  60  30

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY FROM 5 PM SATURDAY TO 3 PM PDT SUNDAY
     ORZ044-507-508.

     WIND ADVISORY FROM 11 AM TO 11 PM PDT SATURDAY ORZ511.

     WIND ADVISORY FROM 5 AM TO 8 PM PDT SATURDAY FOR LADD AND PYLES
     CANYONS IN THE ORZ049.

WA...WIND ADVISORY FROM 5 PM SATURDAY TO 3 PM PDT SUNDAY WAZ028-029.

&&

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

$$

90/82/82






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