606 
FXUS66 KPDT 210605 AAA
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
955 PM PST FRI NOV 20 2009

UPDATED THE AVIATION DISCUSSION

.UPDATE...THE LATEST RADAR WAS SHOWING THE SHOWERS FROM EARLIER WERE 
MOVG EAST OF THE AREA WITH DRIER AIR ADVECTING INTO MOST OF THE 
COLUMBIA BASIN. AS A DEPARTING TROUGH OF LOW PRESSURE EXITS THE AREA 
OVERNIGHT...CLOUDS AND SOME SHOWERS WILL LINGER ACROSS THE REGION 
AND ESPECIALLY IN THE MOUNTAINS WHERE MINOR ACCUMULATIONS OF SNOW 
ARE STILL POSSIBLE. OTHER THAN MAKING SOME ADJUSTMENTS TO POPS AND 
WEATHER ALONG WITH SKY THE PRESENT SHORT TERM FORECAST APPEARS ON 
TRACK FOR NOW.

.AVIATION...VFR CONDITIONS WILL PERSIST UNTIL MORNING UNTIL THE NEXT 
STORM SYSTEM EFFECTS THE REGION TOMORROW. AFTER 12Z MVFR CONDITIONS 
ARE POSSIBLE AS TAF SITES KYKM...KDLS...KRDM DUE TO LOWERING 
CEILINGS AND THEN THE REMAINDER OF THE TAF SITES WILL BE EFFECTED 
AFTER 15Z. EARLY TOMORROW NIGHT AFTER 02Z TAF SITES KDLS AND KRDM 
MAY EXPERIENCE BRIEF IFR CONDITIONS IN SHOWERS THAT WILL LOWER 
CEILINGS.

&&

.PREV DISCUSSION... /ISSUED 415 PM PST FRI NOV 20 2009/ 

SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...A FRONT HAS CROSSED 
OVER THE CASCADES WITH BREEZY TO WINDY SOUTHERLY WINDS AHEAD OF 
IT...PARTICULARLY ABOVE 2000 FEET. HIGHER WINDS ALOFT ARE 
OCCASIONALLY MIXING TO THE SURFACE. THE DOWNSLOPING SOUTHEAST WINDS 
IN THE FOOTHILLS OF THE BLUES HAVE DRIED OUT THE LOW LEVELS WITH RHS 
IN THE TEENS AND 20S. THIS HAS LIMITED PRECIPITATION. AS THE COLD 
FRONT MOVES CLOSER EXPECT THE PRECIPITATION TO INCREASE AT ALL 
LOCATIONS EXCEPT THE YAKIMA AND KITTITAS VALLEYS THIS EVENING. WINDS 
WILL BECOME WEST BEHIND THE FRONT AND DECREASE OVERNIGHT. AN UPPER 
LEVEL TROUGH WILL KEEP SHOWERS IN THE NORTHEAST OREGON MOUNTAINS 
OVERNIGHT. DRIER NORTHWEST FLOW WILL BE OVER EASTERN WASHINGTON AND 
OREGON SATURDAY WITH UPSLOPE SLOPE FLOW KEEPING SHOWERS IN THE 
MOUNTAINS. ANOTHER FRONT WILL INCREASE RAIN AND SNOW OVER THE EAST 
SLOPES OF THE CASCADES SATURDAY AFTERNOON...AND SPREAD OVER THE REST 
OF EASTERN WASHINGTON AND OREGON SATURDAY NIGHT AND SUNDAY. SUNDAY 
AFTERNOON THE UPPER LEVEL TROUGH WILL MOVE THROUGH EASTERN 
WASHINGTON AND OREGON AND WESTERLY FLOW WILL START RAIN SHADOWING IN 
THE LOWER COLOMBIA BASIN AND DESCHUTES PLATEAU. UPPER LEVEL RIDGING 
WILL BUILD NEAR THE COAST SUNDAY NIGHT AND STOP THE PRECIPITATION 
EXCEPT FOR SLOP OVER PRECIPITATION IN THE CASCADES AND UPSLOPE FLOW 
IN NORTHEAST OREGON MOUNTAINS.  COONFIELD  

LONG TERM...MONDAY THROUGH FRIDAY...MODELS SHOW A MID/UPPER LEVEL 
RIDGE OF HIGH PRESSURE MOVE THROUGH THE FORECAST AREA ON MONDAY FOR 
MAINLY DRY CONDITIONS EXCEPT ALONG THE EAST SLOPES OF THE CASCADES 
WHERE RAIN AND MOUNTAIN SNOW ARE LIKELY. THE RIDGE REMAINS OVER THE 
PACIFIC NORTHWEST MONDAY NIGHT THROUGH THANKSGIVING DAY FOR DRY 
CONDITIONS...EXCEPT ALONG THE EAS FACING SLOPES OF THE CASCADES 
WHERE THERE WILL BE A CHANCE OF SLOP OVER PRECIPITATION FROM THE 
WEST SIDE OF WASHINGTON AND OREGON. MODELS HAVE STRONG AGREEMENT IN 
SHOWING A MID/UPPER LEVEL TROUGH PUSHING A COLD FRONT AND ASSOCIATED 
RAIN THROUGH THE FORECAST AREA THURSDAY NIGHT AND FRIDAY.  POLAN

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  36  51  36  50 /  20  10  70  60 
ALW  39  52  36  49 /  20  10  70  60 
PSC  31  47  36  51 /  10  10  70  40 
YKM  28  44  30  50 /  10  20  70  40 
HRI  32  50  34  50 /  10  10  70  50 
ELN  27  41  27  42 /  10  30  70  40 
RDM  22  42  30  45 /  10  30  70  40 
LGD  32  41  33  44 /  60  20  80  70 
GCD  29  42  29  42 /  40  10  70  60 
DLS  36  45  36  52 /  10  30  80  40 

&&

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

THREAT INDEX
SATURDAY : GREEN
SUNDAY : GREEN
MONDAY : GREEN

GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES.
YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.
RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT.

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

$$

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