Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 261611
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
810 AM PST WED NOV 26 2014

.SHORT TERM...TODAY AND TONIGHT...RIDGE OF HIGH PRESSURE WILL BE
OVER THE REGION WITH THE MAIN MOISTURE STREAM STAYING NORTH OF THE
FORECAST AREA TODAY AND THEN BEGINNING TO DROP SOUTHWARD LATE
TONIGHT. COULD SEE A FEW SHOWERS NEAR THE CREST OF THE CENTRAL
WASHINGTON CASCADES TODAY BUT THEN SPREADING SOUTHWARD DOWN THE
CASCADES INTO OREGON AND INTO THE MOUNTAINS OF EASTERN OREGON LATE
TONIGHT. TEMPERATURES WILL CONTINUE TO BE MILD AND ABOVE NORMAL
TODAY AND TONIGHT.

&&

.PREV DISC... /ISSUED 440 AM PST WED NOV 26 2014/

SHORT TERM...TODAY THROUGH FRIDAY...THE RAIN HAS MOVED OFF TO THE
NORTHEAST WITH JUST A FEW SHOWERS OVER THE CENTRAL WASHINGTON
CASCADES AT THIS TIME. EXPECT THESE TO CONTINUE TODAY. ELSEWHERE IT
WILL BE A DRY DAY AS AN UPPER RIDGE AMPLIFIES OVER THE REGION.
TEMPERATURES WILL BE QUITE MILD FOR THIS TIME OF YEAR WITH THE LOWER
ELEVATIONS AROUND OR JUST OVER 60 DEGREES EXPECTED BOTH TODAY AND
THURSDAY. A WEAK COLD FRONT WILL CAUSE AN INCREASE IN CLOUDS AND
MORE RAIN TO THE MOUNTAINS LATE TONIGHT INTO THURSDAY. HOWEVER...
DOWNSLOPE DRYING EFFECTS WILL KEEP THE BASIN AND ADJACENT VALLEYS
DRY ON THURSDAY. A STRONGER COLD FRONT WILL DROP DOWN OUT OF CANADA
THURSDAY NIGHT INTO FRIDAY WHICH WILL INCREASE THE CHANCES OF
PRECIPITATION ACROSS THE CWA. BY FRIDAY MORNING ALL AREAS SHOULD SEE
SOME RAINFALL. TEMPERATURES AHEAD OF THIS COLD FRONT WILL CONTINUE
TO BE QUITE MILD ON FRIDAY...THOUGH A FEW DEGREES COOLER THAN
THURSDAY. MUCH COLDER AIR IS STILL EXPECTED GOING INTO THE EXTENDED
FORECAST. IT WILL BE LOCALLY BREEZY TO WINDY THROUGH THE SHORT TERM
ESPECIALLY ON THE RIDGE TOPS AND EXPOSED OPEN TERRAIN EACH DAY IN
THE SHORT TERM. 88

LONG TERM...FRIDAY NIGHT THROUGH TUESDAY...LATEST MODEL RUNS
INDICATE THAT THE MID/UPPER LEVEL TROUGH IN SOUTHERN BRITISH
COLUMBIA BECOMES THE DOMINANT SYSTEM RELATIVE TO THE MID/UPPER LEVEL
TROUGH OFFSHORE, WHICH WEAKENS CONSIDERABLY ON FRIDAY AS IT GETS
CAPTURED BY COMING INTO PHASE WITH THE AFOREMENTIONED BRITISH
COLUMBIA TROUGH. AS SUCH THE TROUGH BECOMES PROGRESSIVE AND MOVES
SOUTHEAST ACROSS THE PACIFIC NORTHWEST FRIDAY NIGHT AND SATURDAY.
THIS RESULTS IN THE FRONTAL BOUNDARY MOVING SOUTH INTO CENTRAL
OREGON DURING THE DAY ON SATURDAY FOR DRY CONDITIONS SETTING IN
ACROSS SOUTHEAST WASHINGTON ON SATURDAY. SNOW LEVELS START OUT AT
4000-6000 FEET FRIDAY EVENING AND DROP LIKE A ROCK TO THE FLOOR OF
THE LOWER COLUMBIA BASIN BY DAYBREAK ON SATURDAY BY VIRTUE OF THE
TROUGH DROPPING OUT OF BRITISH COLUMBIA AND USHERING IN AN ARCTIC
AIRMASS. HIGH TEMPS ON SATURDAY WILL BE IN THE 30S. BY DAYBREAK ON
SUNDAY THE TROUGH MOVES EAST INTO IDAHO/MONTANA FOR A BREAK IN
PRECIPITATION FOR ALL OF FORECAST AREA THROUGHOUT SUNDAY. HOWEVER, I
KEPT A CHANCE OF SNOW IN CENTRAL OREGON TO ALLOW FOR POSSIBILITY OF
A WARM FRONT MOVING INTO SOUTHWEST OREGON AND MAYBE INTO CENTRAL
OREGON BY SUNDAY AFTERNOON. THE NEXT PACIFIC TROUGH TAKES SHAPE NEAR
130-140W ON SUNDAY AND THIS SYSTEM LOOKS TO MOVE INTO CALIFORNIA ON
MONDAY AND TUESDAY.  POLAN

AVIATION...12Z TAFS...SPOTTY AREAS OF FOG AND LOW CLOUDS HAVE
DEVELOPED OVER THE LOWER COLUMBIA BASIN WITH CEILINGS 003-008.
OTHERWISE, CLOUD BASES ARE AROUND 20000 FT AGL, EXCEPT AT KDLS WHERE
CEILINGS ARE 060-080. DOWNSLOPE WINDS AT KALW HAVE MIXED OUT THE FOG
AND DEWPOINT DEPRESSION AT KALW IS SUCH THAT FOG IS NOT EXPECTED TO
FORM AGAIN THIS MORNING. CONDITIONS WILL IMPROVE THROUGH TODAY
ALTHOUGH SKIES SHOULD REMAIN BKN-OVC WITH CLOUDS BASES ABOVE 15000
FT AGL. WINDS WILL BE MOSTLY 5-10 KTS.  POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  60  50  60  44 /   0  10  10  20
ALW  61  51  60  47 /   0  10  10  20
PSC  59  47  59  44 /   0  10  10  20
YKM  53  41  53  37 /  10  10  10  20
HRI  62  47  60  44 /   0  10  10  20
ELN  52  41  52  36 /  10  20  20  50
RDM  58  37  58  37 /   0  10  10  20
LGD  53  45  52  40 /   0  20  20  40
GCD  54  44  55  41 /   0  10  10  40
DLS  62  47  60  42 /  10  10  20  40

&&

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

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

$$

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