Area Forecast Discussion
Issued by NWS Pendleton, OR

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000
FXUS66 KPDT 190959
AFDPDT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
159 AM PST FRI DEC 19 2014

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT...AN ACTIVE WEATHER
PATTERN IS EXPECTED DURING THE NEXT FEW DAYS. A WEATHER SYSTEM IS
CURRENTLY MOVING THROUGH THE CWA AT THIS TIME WITH AREAS OF RAIN AND
MOUNTAIN SNOW FROM THE CASCADES EASTWARD ACROSS EASTERN WA/OR. THE
SNOW LEVELS ARE LOW ENOUGH WITH TRAPPED COLD AIR ALONG THE
WASHINGTON CASCADE EAST SLOPES SUCH THAT A WINTER WEATHER ADVISORY
IS IN EFFECT THERE. THE SNOW WILL TAPER OFF BY MORNING AND THE
ADVISORY ENDS AT 7 AM. SNOW LEVELS WILL RISE TO BETWEEN 2500 FEET IN
NORTHWEST AREAS TO AROUND 4500 FEET IN CENTRAL OREGON. THE BLUE
MOUNTAINS WILL HAVE SNOW LEVELS AROUND 3500 FEET...WHICH MAY BE
PESSIMISTIC GIVEN THE FACT THAT KMEH IS AT 37 DEGREES AND LIGHT RAIN
IS FALLING. WILL NEED TO RAISE SNOW LEVELS IN THE BLUE MOUNTAINS
THIS MORNING. GUSTY SOUTHERLY WINDS ARE OCCURRING IN THE SOUTHERN
GRANDE RONDE VALLEY THIS MORNING WITH WIND SPEEDS BETWEEN 20-30 MPH
WITH GUSTS TO 35-40 MPH. THIS IS NEAR ADVISORY CRITERIA AND WILL
HAVE TO KEEP A CLOSE EYE ON IT EARLY THIS MORNING IN CASE AN
ADVISORY BECOMES NEEDED. THERE WILL BE A BRIEF BREAK IN THE WEATHER
THIS AFTERNOON AND EVENING BUT STILL SOME RAIN AND MOUNTAIN SNOW
SHOWERS OVER THE CASCADE EAST SLOPES AND THE NORTHEAST MOUNTAINS.
THE NEXT SYSTEM WILL BE STRONGER AND WETTER AS A STRONG WESTERLY 125
KT JET STREAM MOVES INTO THE PACIFIC NORTHWEST. THIS WILL PROVIDE
SIGNIFICANT UPSLOPE PRECIPITATION WITH SPILL OVER OVER THE CASCADES
AND THEN SOME UPSLOPE ENHANCEMENT OVER THE EASTERN AND NORTHEAST
MOUNTAINS. EXPECT FROM 3 TO 6 INCHES OF RAIN OVER THE CASCADES AND 2
TO 3 INCHES OVER THE NORTHEAST MOUNTAINS. SNOW LEVELS WILL RISE TO
AROUND 8000 FEET BY SATURDAY EVENING WHICH WILL KEEP THE
PRECIPITATION AS MAINLY RAIN OVER THE MOUNTAINS. SMALL RIVERS AND
STREAMS ARE LIKELY TO RISE AND THERE MAY BE SOME LOCAL FLOODING ON
THEM. THE LARGER MAIN STEM RIVERS WILL SEE SIGNIFICANT RISES BUT ARE
NOT AT THIS TIME EXPECTED TO GO ABOVE FLOOD STAGE. SOME RIVERS ARE
EXPECTED TO REACH ACTION STAGE THOUGH AND THAT WILL BE COVERED WITH
RIVER STATEMENTS. IN ADDITION TO THE RAINFALL THE WINDS WILL
INCREASE SIGNIFICANTLY SATURDAY NIGHT AND SUNDAY DUE TO DOWNWARD
TRANSPORT AND MIXING SUCH THAT THERE MAY BE WIND ADVISORIES
NEEDED...ESPECIALLY FOR THE BLUE MOUNTAINS AND FOOTHILLS AND
LADD/PYLES CANYONS. TEMPERATURES WILL BE ON A WARMING TREND THROUGH
THE SHORT TERM PERIOD. 88

.LONG TERM...SUNDAY THROUGH FRIDAY...AN UPPER LEVEL RIDGE WILL BUILD
OVER THE PACIFIC NORTHWEST SUNDAY THROUGH TUESDAY. THIS WILL RESULT
IN MILD TEMPERATURES FOR THIS TIME OF YEAR AND HIGH SNOW LEVELS.
THERE WILL STILL BE PLENTY OF MOISTURE AND RAINFALL ON SUNDAY AND
SUNDAY NIGHT. HEAVY AMOUNTS OF RAIN ARE LIKELY IN THE MOUNTAINS. IT
WILL ALSO BE WINDY SUNDAY MORNING WITH AT LEAST ADVISORY LEVEL WINDS
POSSIBLE. A SLIGHT DRYING TREND WILL FOLLOW FOR MONDAY AND TUESDAY
WITH JUST A CHANCE OF MAINLY MOUNTAIN SHOWERS. ON WEDNESDAY A
MODERATELY STRONG SHORTWAVE TROUGH WILL MOVE ACROSS THE AREA
USHERING IN MUCH COLDER AIR BY WEDNESDAY NIGHT WITH RAIN CHANGING TO
SNOW AREAWIDE. THE SNOW WILL LINGER IN THE EAST ON CHRISTMAS DAY. AS
OF NOW IT LOOKS LIKE SNOW ACCUMULATIONS WILL BE MOSTLY LIGHT. IT
WILL BE COLD THURSDAY NIGHT AND FRIDAY WITH BELOW NORMAL
TEMPERATURES AND MOSTLY DRY CONDITIONS. 78

&&

.AVIATION...12Z TAFS...WIDESPREAD MVFR/IFR CIGS/VSBYS IN FOG AND
RAIN ARE EXPECTED THIS MORNING WITH SOME IMPROVEMENT AFTER 18Z
POSSIBLE. WINDS WILL BE LIGHT ALTHOUGH SOME 5 TO 10 KT WINDS MAY
DEVELOP THIS AFTERNOON MAINLY FROM THE SW. AFTER 03Z EXPECT CIGS TO
LOWER ONCE AGAIN TO MVFR/IFR WITH SOME FOG FOR THE BALANCE OF THE
NIGHT. LIFR VSBYS ARE NOT EXPECTED SATURDAY MORNING. 78

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  46  34  49  43 /  70  20  80  80
ALW  46  36  48  43 /  80  20  80  80
PSC  48  36  48  40 /  60  10  80  50
YKM  44  32  42  33 /  50  20  80  40
HRI  47  35  49  41 /  60  20  80  50
ELN  41  31  39  31 /  50  20  80  70
RDM  44  33  48  39 /  60  30  80  60
LGD  41  34  42  38 /  80  20  90  90
GCD  41  33  42  39 /  80  20  80  90
DLS  47  36  46  41 /  70  30  90  70

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...AIR STAGNATION ADVISORY UNTIL 10 AM PST THIS MORNING WAZ026>028.

     WINTER WEATHER ADVISORY UNTIL 7 AM PST THIS MORNING ABOVE 2500
     FEET FOR THE WAZ520.

&&

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

$$

88/78/78




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