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Area forecast discussion 
National Weather Service Pendleton or
244 PM PST Friday Nov 28 2014

Short term...tonight through Sunday...the latest Pacific system
will move through the Pacific northwest tonight through Saturday.
This system will push a marine polar front through the region during
the early morning hours Saturday, then an Arctic front will move
through during the day Saturday. Breezy to windy conditions will
continue through this evening with strongest winds over the Lower
Basin and Yakima Valley in Washington. Onshore flow tonight will
produce varying amounts of rain and snow. Snow levels will begin to
fall along the Washington Cascade east slopes late this evening.
Elsewhere, snow levels will fall overnight through middle morning
Saturday with the passage of the marine polar front. Snow levels
will fall further, reaching the lowest elevations by Saturday
afternoon due to the Arctic front. Overall snowfall will be limited
below 5000 feet due to the timing of the system and the snow level
drop. Some light upslope induced snow will be possible along the
north and northeast facing mountain slopes and foothills into
Saturday evening as the Arctic air mass continues to filter into the
area. Expect fair, dry and cold conditions late Saturday night
through Sunday. 90

Long term...Sunday night through Wednesday night...warm front will
be lifting north late Sunday night and across northern Oregon on
Monday. There is still a lot of disagreement in the models on how
far north into Washington the warm front will move by Monday night.
At this time it appears it will remain south of a line from Yakima
to Pullman and then get pushed back south on Tuesday as another
piece of energy drops south across Washington. Model soundings
indicate a chance of freezing rain...sleet and snow in the Columbia
River gorge, part of north central Oregon from Madras north and the
foothills of the Blue Mountains and lower Columbia Basin of Oregon
Monday afternoon and evening. Then by Tuesday the cold air is washed
out, leaving a chance of rain or snow across northern Oregon on
Tuesday. The flow becomes more westerly on Wednesday with mountain
showers. Ml

Thursday through major weather concerns are anticipated
in days 6-7 of the forecast. A westerly flow will keep a chance of
snow showers over the mountains and a slight chance of rain and snow
showers elsewhere. Even though the snow levels will be near the
basin floor at night...the threat of precipitation is minimal for
the lower Columbia Basin and surrounding valleys. Models are hinting
at a weak ridge on Friday...and the upcoming shift may decide to
remove probability of precipitation for most of the area if this model trend continues.


Aviation...00z tafs...winds 20-30 kts will be seen at most
locations through 06z tonight with the exception of kdls which will
be 15-25 kts. Cold front will be working south over Washington
tonight with main rain band pushed south over Oregon by early
Sunday. MVFR visibility at kdls will continue through 06z as heavier
rain bands move through with light rain showers possible through the
night at other locations. Ml


Preliminary point temps/pops...
PDT 36 37 15 24 / 80 50 20 0
alw 38 39 18 27 / 80 40 20 0
psc 36 38 12 28 / 50 20 10 0
ykm 32 36 12 25 / 30 20 0 0
hri 37 39 11 26 / 40 20 10 0
eln 28 34 9 26 / 40 20 0 0
rdm 34 37 12 29 / 70 40 20 0
lgd 39 41 13 27 / 80 70 30 0
gcd 35 37 13 30 / 60 70 20 0
dls 39 43 23 29 / 70 30 10 0


PDT watches/warnings/advisories...
Washington...Wind Advisory until 10 PM PST this evening waz027-028.


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