Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 101751 AAB
AFDPDT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
951 AM PST WED FEB 10 2016

UPDATED AVIATION DISCUSSION

.SHORT TERM...MORNING UPDATE...THE UPPER RIDGE OVER THE WESTERN U.S.
WILL WEAKEN OVER THE PACIFIC NORTHWEST TODAY AS A WEAK UPPER LEVEL
DISTURBANCE MOVES THROUGH THE REGION. THIS DISTURBANCE WILL BRING
VARIABLE AMOUNTS OF MID AND HIGH LEVEL CLOUDINESS TO THE REGION, BUT
ONLY LIMITED AMOUNTS OF PRECIP. AT THIS TIME, PRECIP IS EXPECTED TO
MAINLY OCCUR NEAR THE CASCADE CREST. THE FORECAST PACKAGE COVERS THE
PRECIP OCCURRENCES WELL AND ONLY MADE MINOR ADJUSTMENTS. FOG HAS
BEEN LIMITED ACROSS THE AREA THIS MORNING, WITH THE BASE OF THE
INVERSION OVER THE COLUMBIA BASIN BEING A BIT LOWER THAN YESTERDAY.
THUS ADJUSTED FOG LOCATIONS ACROSS THE AREA. ALSO, A FEW ADJUSTMENTS
TO SKY COVER AND WINDS WERE MADE FOR THIS UPDATE. 90

.LONG TERM...PREVIOUS DISCUSSION...AS THE COLD FRONT MAKES ITS WAY
ACROSS THE AREA...EXPECT RAIN FRIDAY NIGHT CHANGING OVER TO SNOW
ABOVE 3500 FT MSL BY SATURDAY MORNING. ANY NEW SNOW ACCUMULATIONS
ARE EXPECTED TO BE LIGHT DUE TO THE WET NATURE OF THE
PRECIPITATION...AND THAT SURFACE TEMPERATURES WILL LIKELY STILL BE
WARM AND ABOVE FREEZING DURING THE CHANGE OVER PROCESS. EXPECT
BREEZY TO WINDY CONDITIONS ACROSS THE LOWER ELEVATIONS ON SATURDAY
WITH THE COLD FRONT PASSAGE.

SUNDAY AND MONDAY...THE OVERALL PATTERN WILL STAY IN A PROGRESSIVE
WESTERLY FLOW...BUT SNOW LEVELS WILL BE ON THE RISE FOR THE MOST
PART...REBOUNDING TO ABOUT 7000-8000 FT MSL BY MONDAY AFTERNOON.
MOISTURE BANDS WILL ACCOMPANY THIS PROGRESSIVE FLOW...ALONG WITH MID
AND LOW LEVEL WIND INCREASES. AS A RESULT CERTAIN AREAS...ESPECIALLY
RIDGETOPS MAY BE BREEZY SUNDAY NIGHT INTO MONDAY...WITH FAIRLY
DECENT POP CHANCES THROUGH SUNDAY NIGHT.

HAVE TRANSITIONED TO A MORE CLIMO POP MONDAY THROUGH WEDNESDAY AS
MODEL QPF PLACEMENT VARIES FROM DAY TO DAY. A FEW OTHER MODEL
DISCREPANCIES IN THE EXTENDED AS WELL...REGARDING PRECIPITATION.
WILL WAIT TO SEE WHETHER OR NOT THE DRIER AIR TO THE SOUTH WILL
ATTEMPT TO SHIFT NORTH JUST ENOUGH TO PUSH THE MOISTURE BANDS NORTH
OF OUR FORECAST AREA. THIS WOULD SIGNIFICANTLY REDUCE POPS FOR THE
MONDAY EVENING THROUGH WEDNESDAY TIME PERIOD. ANOTHER DISCREPANCY IN
THE GFS/ECMWF MODEL IS THAT ECMWF HAS A FAST MOVING COLD FRONT...
WHICH RESULTS IN A BRIEF LOWERING OF THE SNOW LEVELS ON MONDAY NIGHT
INTO TUESDAY NIGHT. THIS MODEL SUGGESTS THAT SNOW LEVELS WOULD ONCE
AGAIN DROP TO ABOUT 3500 FT MSL. HAVE NOT GONE THIS ROUTE WITH THE
FORECAST...BUT WILL CONTINUE TO MONITOR THE NEXT MODEL RUNS FOR
CHANGES.

ANOTHER COLD FRONT CAN BE EXPECTED TO IMPACT ALL AREAS NEXT
WEDNESDAY EVENING...STAY UP TO DATE WITH UPCOMING DISCUSSIONS TO SEE
HOW STRONG/WEAK THIS NEXT COLD FRONT IS EXPECTED TO BE.

&&

.AVIATION...18Z TAFS...VFR CONDITIONS WILL BE PREVALENT OVER THE
NEXT 24 HOURS. LINGERING MVFR VISIBILITIES WILL BE POSSIBLE AT KPSC
FOR THE NEXT HOUR OR TWO. A WEAK DISTURBANCE WILL BE MOVING ACROSS
THE AREA TODAY AND TONIGHT AND THERE WILL BE INCREASING MID AND
UPPER LEVEL CLOUDS TODAY BECOMING OVERCAST AT 5000-10000 FEET AGL
TONIGHT. PRECIPITATION WILL BE CONFINED MAINLY TO THE CASCADES. WITH
THE SYSTEM OVER THE AREA THE CHANCES FOR FOG LOOK TO BE LESS THAN
THE LAST COUPLE OF NIGHTS SO HAVE CONFINED MVFR VISIBILITY TO KDLS
AFTER 15Z. WINDS WILL REMAIN BELOW 12 KTS FOR THE NEXT 24 HOURS.
PERRY

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  53  36  54  39 /   0   0  10  10
ALW  51  38  54  41 /   0   0  10  10
PSC  52  35  51  37 /   0   0  10  10
YKM  53  35  49  37 /   0  10  20  20
HRI  52  36  52  38 /   0   0  10  10
ELN  43  31  42  35 /   0  10  20  30
RDM  63  34  59  38 /   0  10  10  10
LGD  47  34  49  37 /   0   0   0  10
GCD  61  31  52  34 /   0   0  10  10
DLS  55  40  54  41 /   0  10  20  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...AIR STAGNATION ADVISORY UNTIL 10 AM PST SATURDAY FOR ORZ041-044-
     050-505-507-508-510.

WA...AIR STAGNATION ADVISORY UNTIL 10 AM PST SATURDAY FOR WAZ024-
     026>029-520-521.

&&

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

$$

90/89/83



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