Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 251153 AAA
AFDPDT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PENDLETON OR
353 AM PST THU DEC 25 2014

UPDATED AVIATION DISCUSSION

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT...A NORTHWEST FLOW WILL
PERSIST OVER THE REGION THROUGH THIS PERIOD. LINGERING MOISTURE AND
WEAK DISTURBANCES WITHIN THIS FLOW WILL CAUSE VARIABLE AMOUNTS OF
CLOUDINESS AND A FEW SHOWERS. THE SHOWERS WILL BE PRIMARILY SNOW,
AND WILL FAVOR NORTH AND NORTHWEST FACING MOUNTAIN SLOPES. ALSO
AREAS NEAR THE CASCADE CREST MAY SEE A FEW OF THESE SNOW SHOWERS.
SNOW AMOUNTS WILL BE LIMITED TO 2 INCHES OR LESS, AND WILL WILL BE
SPOTTY IN COVERAGE. A STRONGER SYSTEM WITHIN THIS FLOW WILL BEGIN TO
APPROACH AND AFFECT THE REGION LATE IN THE FRIDAY NIGHT PERIOD. THIS
SYSTEM WILL CAUSE INCREASING CHANCES OF SNOW OVER THE CENTRAL
WASHINGTON CASCADE EAST SLOPES AFTER MIDNIGHT FRIDAY/SATURDAY. WINDS
WILL CONTINUE TO DECREASE THROUGH TODAY. TEMPS WILL BE SEASONABLY
COOL THROUGH THIS PERIOD, THOUGH MOUNTAIN VALLEYS WITH SNOW WILL SEE
COLD OVERNIGHT LOW TEMPS. SOME PATCHY FOG MAY BE POSSIBLE IN THE
COLUMBIA BASIN FRIDAY. FOR NOW WILL LEAVE OUT OF THE FORECAST AS NOT
CERTAIN AS TO THE EXTENT OF COVERAGE DUE TO THE PASSAGE OF MID AND
HIGH CLOUDINESS THROUGH THE PERIOD. 90

.LONG TERM...SATURDAY THROUGH THURSDAY...A SYSTEM WILL MOVE IN OUT
OF THE GULF OF ALASKA SATURDAY WITH A CHANCE OF MOUNTAIN SNOW AND A
SLIGHT CHANCE OF A RAIN/SNOW MIX. SNOW LEVELS WILL BE AROUND 1500 TO
2000 FEET IN THE MORNING THEN RISE TO 2000 TO 2500 FEET IN THE
AFTERNOON. THE FULL IMPACT OF THIS SYSTEM WILL BE ON SATURDAY NIGHT
WHEN THERE WILL BE A CHANCE OF RAIN AND SNOW IN THE LOWER ELEVATIONS
AND SNOW IN THE MOUNTAINS. PRECIPITATION AMOUNTS LOOK GENEROUS,
ESPECIALLY IN THE MOUNTAINS AND ANTICIPATE THAT WINTER WEATHER
HIGHLIGHTS WILL BE NEEDED. A TROUGH WILL HAVE DEVELOPED OVER THE
AREA AND AN UNSTABLE NORTHERLY FLOW WILL KEEP RAIN AND SNOW SHOWERS
OVER THE AREA SUNDAY BEFORE TAPERING OFF SUNDAY NIGHT. BY MONDAY A
CLOSED LOW WILL HAVE DEVELOPED IN THE TROUGH SOUTH OF OUR AREA. WE
WILL DRY OUT BUT THE NORTHERLY FLOW WILL TURN TEMPERATURES MUCH
COLDER. MODELS SHOW THE TROUGH REMAINING THROUGH THURSDAY WITH THE
CLOSED LOW DIVING WELL TO OUR SOUTH. THERE WILL BE FAIR AND DRY
WEATHER MONDAY THROUGH THURSDAY. TEMPERATURES WILL START OUT IN THE
MID 30S TO LOWER 40S WITH 30S IN THE MOUNTAINS SATURDAY THEN COOL
ABOUT 5 DEGREES SUNDAY. MONDAY WILL STRUGGLE TO REACH FREEZING EVEN
IN THE WARMEST LOCATIONS. TUESDAY THROUGH THURSDAY WILL BE IN THE
20S TO LOWER 30S. MONDAY NIGHT THROUGH WEDNESDAY NIGHT WILL BE IN
THE TEENS WITH SINGLE DIGITS IN THE MOUNTAINS. PERRY

&&

.AVIATION...12Z TAFS...A DISTURBANCE HAS LEFT THE AREA OVERNIGHT AND
HAS BEEN REPLACED BY A NORTHERLY FLOW. VFR CONDITION ARE EXPECTED
THROUGH AT LEAST THIS EVENING. A FEW UPSLOPE SNOW SHOWERS ARE
POSSIBLE IN THE MOUNTAINS BUT WILL NOT AFFECT ANY TAF SITES. AFTER
06Z TONIGHT, MOS GUIDANCE SUGGEST SOME LOW STRATUS AND MVFR
VISIBILITIES FORMING, ESPECIALLY AT KDLS AND KALW, BUT
TEMPERATURE/DEW POINT SPREADS SUGGEST IT WILL BE TOO DRY FOR THIS TO
OCCUR. DUE TO THE UNCERTAINTY, HAVE SCATTERED MVFR CEILINGS AT MOST
TAF SITES AFTER 06Z AND 6SM AT KDLS AND KALW TO COVER THIS. WINDS
WILL GENERALLY REMAIN BELOW 15 KTS THOUGH KDLS, KPDT, KRDM AND KBDN
MAY HAVE A FEW GUSTS TO 20 KTS THIS AFTERNOON. PERRY

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  39  27  38  28 /  10  10  10  10
ALW  39  29  36  30 /  10  10  10  10
PSC  43  26  38  28 /   0   0  10  10
YKM  40  24  36  26 /   0   0  10  10
HRI  43  25  38  28 /  10   0  10  10
ELN  41  23  35  25 /  10   0  10  10
RDM  38  21  40  20 /  10  10  10  10
LGD  37  23  35  22 /  20  20  10  10
GCD  37  23  39  22 /  20  20  10  10
DLS  47  33  44  31 /  10  10  10  10

&&

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

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

$$

90/83/83





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