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

.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.

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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