Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 252247 CCA
AFDPDT

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE PENDLETON OR
248 PM PDT SAT OCT 25 2014

CORRECTED WATCHES/WARNINGS/ADVISORIES SECTION

.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...THE STRONG LOW PRESSURE
SYSTEM CONTINUES TO APPROACH WESTERN WASHINGTON AT THE MOMENT. THIS
SYSTEM WILL CONTINUE TO TRACK NORTHEAST TO SOUTHERN BRITISH COLUMBIA
TONIGHT, THEN SOUTHERN SASKATCHEWAN BY LATE SUNDAY AFTERNOON.
LOCALLY TIGHT PRESSURE GRADIENTS REMAIN OVER CENTRAL OREGON AND EAST
CENTRAL OREGON, AS WELL AS THE SOUTH ENDS OF THE GRANDE RONDE AND
WALLOWA VALLEYS. WINDS HAVE BEEN WELL WITHIN THE 25 TO 35 MPH
SUSTAINED WITH GUSTS OF 45 TO 55 MPH IN CENTRAL OREGON AND AT THE
SOUTH END OF THE WALLOWA VALLEY. THE SOUTH END OF THE GRANDE RONDE
VALLEY HAS NOT DONE AS WELL, BUT MAY STILL PICK UP WITH THE APPROACH
THE SYSTEM`S COLD FRONT THIS EVENING. THUS WILL CONTINUE THE CURRENT
ADVISORIES IN CENTRAL OREGON AND IN THE GRANDE RONDE AND WALLOWA
VALLEYS. STILL EXPECT A BURST OF STRONG WINDS WITH THE PASSAGE OF
THE SYSTEM`S COLD FRONT ACROSS THE COLUMBIA BASIN THIS EVENING. ALSO
GRADIENTS FROM LATE TONIGHT INTO SUNDAY MORNING ARE STILL EXPECTED
TO RESULT IN OFF AND ON STRONG WINDS. THUS WILL CONTINUE THE WIND
ADVISORIES IN THE LOWER BASIN AND FOOTHILLS. HAVE ALSO ADDED
ADVISORIES FOR NORTH-CENTRAL OREGON AND SIMCOE HIGHLANDS. WILL SEE
SHOWERS TONIGHT, ESPECIALLY AS THE FRONT MOVES THROUGH. WILL MENTION
A SLIGHT CHANCE OF A THUNDERSTORM TO THE FOOTHILLS AND BLUE
MOUNTAINS IN UMATILLA, WALLA WALLA AND COLUMBIA COUNTIES DUE TO
POTENTIAL OROGRAPHIC ENHANCEMENT OF THE SHOWERS WITH THE FRONT.
MOIST ONSHORE FLOW WILL KEEP VARYING CHANCE OF SHOWER GOING OVER THE
AREA LATE TONIGHT THROUGH SUNDAY. THESE SHOWERS WILL DECREASE SUNDAY
NIGHT. SNOW LEVELS WILL FALL OVERNIGHT AND REMAIN BETWEEN 4500 AND
5500 FEET MSL SUNDAY AND SUNDAY NIGHT. THUS SOME LIGHT, LOCALIZED
SNOW AMOUNTS WILL BE POSSIBLE ABOVE THESE LEVELS. 90

.LONG TERM...MONDAY THROUGH WEDNESDAY...GFS AND EC IN GOOD
AGREEMENT. A WET BUT MILD PATTERN WILL PREVAIL. A WARM FRONT WITH
ABUNDANT PACIFIC MOISTURE WILL HIT THE CASCADES LATE MONDAY AND
SPREAD INTO THE REST OF THE AREA MONDAY NIGHT AND TUESDAY. THIS
SYSTEM WILL INCLUDE SOME RESIDUAL MOISTURE FROM HURRICANE ANA. FOR
WEDNESDAY...THE WESTERLY FLOW WILL LIMIT RAIN TO MAINLY THE CASCADES
AND EASTERN MOUNTAINS. TEMPERATURES WILL AVERAGE MORE THAN 10
DEGREES ABOVE NORMAL IN MOST SPOTS ESPECIALLY AT NIGHT WITH THE
CLOUD COVER. A FEW MOUNTAIN VALLEY AREAS WILL SEE GUSTY WINDS ON
TUESDAY.

THURSDAY THROUGH SATURDAY...THE PERIOD STARTS OFF WITH AN UPPER
LEVEL RIDGE CENTERED OVER THE INTERMOUNTAIN WEST AND AN APPROACHING
UPPER LEVEL TROUGH NEAR 130 WEST OVER THE PACIFIC. OUT AHEAD OF THIS
FEATURE EXPECT A MOIST SOUTHWESTERLY FLOW TO BRING A CHANCE OF RAIN
ALONG THE CASCADES AND A SLIGHT CHANCE TO THE REST OF THE AREA AS A
WEAK WARM FRONTAL FEATURE MOVES THROUGH. HEADING INTO FRIDAY AND
SATURDAY THE 12Z ECMWF AND 12Z GFS HANDLE THE APPROACHING TROUGH
DIFFERENTLY...THE ECMWF WOULD BRING PLENTY OF MOISTURE INTO THE AREA
AS THE TROUGH STAYS PROGRESSIVE...WHILE THE GFS DEVELOPS A CLOSED
500MB LOW AND SLOWS THE TROUGH DOWN...THE GFS WOULD SUGGEST THE
PRECIPITATION HOLDS OFF UNTIL AFTER AT LEAST 18Z SATURDAY. SINCE
THIS IS DAYS 5-7 DECIDED TO TAKE A BLEND OF THE TWO MODELS TO
ACCOUNT FOR THESE DIFFERENCES. EITHER WAY AS THIS UPPER LEVEL TROUGH
EVENTUALLY MOVES INTO THE REGION EXPECT SNOW LEVELS TO FALL...WITH
BOTH THE ECMWF AND GFS INDICATING 5350-5400M 1000-500MB THICKNESSES
ACROSS THE REGION BY LATE SATURDAY INTO NEXT SUNDAY. OVERALL
TEMPERATURES ARE FORECAST TO BE NEAR AVERAGE THROUGH THE PERIOD. 77

&&

.AVIATION...00Z TAFS...MAIN CONCERN WILL BE WINDS G35-45KT THROUGH
08Z.  STRONG SURFACE LOW WEST OF KAST WILL PROVIDE TIGHT PRESSURE
GRADIENT ACROSS THE AREA THROUGH 08Z.   LOW IS PROGGED TO TRACK NE
INTO BC BY 08Z WITH PRESSURE GRADIENT THEN WEAKENING.  A COLD FRONT
TRAILING FROM THE LOW WILL PROVIDE THE LIFT FOR -SHRA.  TS POSSIBLE
VCTY KALW AND KPDT TIL 06Z...BUT WILL NOT INCLUDE IN TAF DUE TO LOW
CONFIDENCE.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  46  58  40  57 /  40  30  20  10
ALW  49  58  43  58 /  40  30  20  10
PSC  49  63  40  58 /  30  20  10  10
YKM  42  58  35  53 /  50  20  10  10
HRI  48  62  38  58 /  30  20  10  10
ELN  44  57  34  53 /  50  20  10  10
RDM  37  54  27  54 /  50  20  20  10
LGD  45  53  38  52 /  40  40  30  10
GCD  42  54  34  52 /  40  30  20  10
DLS  47  60  41  58 /  60  30  20  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...WIND ADVISORY UNTIL 3 PM PDT SUNDAY ORZ044-507-508.

     WIND ADVISORY UNTIL 11 PM PDT THIS EVENING ORZ511.

     WIND ADVISORY UNTIL NOON PDT SUNDAY ORZ510.

     WIND ADVISORY UNTIL 8 PM PDT THIS EVENING FOR LADD AND PYLES
     CANYONS IN THE ORZ049.

     WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR THE SOUTH END
     OF THE WALLOWA VALLEY.

WA...WIND ADVISORY UNTIL 3 PM PDT SUNDAY WAZ028-029.

     WIND ADVISORY UNTIL NOON PDT SUNDAY WAZ521.

&&

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

$$

90/79/77/79







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