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fxus66 kpdt 181019 

Area forecast discussion
National Weather Service Pendleton or
219 am PST Sat Nov 18 2017

Short through Monday. A low amplitude upper ridge will
be over the region through Sunday. This will result in dry
conditions and mild temperatures. There will be some cloudiness
especially north. Winds will be mostly light except it will be a bit
breezy in the Grande Ronde Valley. Late in the day Sunday and
especially Sunday evening precipitation will begin to spread east of
the Cascades as a shortwave trough flattens the upper ridge. Snow
levels will initially be around 3000 feet along the east slopes of
the Washington some snow will be possible over the
higher elevations before snow levels rise Sunday night. After 06z
Monday precipitation...mostly rain will spread across the entire
forecast area. Snow levels will be high enough such that winter
highlights are not anticipated. There could be some gusty southerly
winds along the Blue Mountain foothills and along the Oregon Cascade
east slopes Sunday night. On Monday a weak boundary will sag
southward across the area pushing the rain southward out of
Washington and eventually northern Oregon by late in the day...but
still good chances for rain all day central Oregon. It will be
rather warm on Monday with highs 50-60 lower elevations and mostly
40s in the mountains. 78

Long term...Monday night through Saturday...models are in fairly
good agreement in the extended forecast from Monday night through
Thursday night. There will be an upper ridge over the inland
northwest with a moist southwest flow on the back side of the ridge
over the forecast area. There will be several warm fronts moving up
over the County Warning Area during this period keeping a chance to likely
precipitation through the period. The wettest days will be from
Tuesday through Wednesday with a very moist warm front. The
southwest flow will cause very mild temperatures. Precipitation
probabilities will be in the chance to likely category with the best
chances in the mountains and somewhat less in the lower elevation.
Snow levels will be fairly high so snow will will be confined to the
higher mountains with little to no accumulation over the passes.
Snow levels will range from 5000 feet Monday night rising to around
10,000 feet by Wednesday and Thursday. A cold front will then move
through the region Thursday night and early Friday. Models begin to
diverge by this time but all are still showing a cold front moving
through the County Warning Area. Snow levels will come back down to around 5000-6000
feet by Friday morning. The precipitation chance will also be
decreasing during this time...especially over the lower elevations.
For Friday night into Saturday the models diverge from each other
more significantly but the general consensus is that another ridge
will develop over the inland northwest with a moist southwest flow
over the County Warning Area again and showery unsettled weather continuing. 88


Aviation...12z tafs...VFR conditions will persist through the next
24 hours. There will be some lower to mid level clouds...especially
over the higher terrain with ceilings around 5k-7k feet mean sea level. Winds
will be light through the period at all taf sites. 88


Preliminary point temps/pops...
PDT 49 32 54 43 / 0 0 0 60
alw 51 35 57 45 / 0 0 0 80
psc 51 32 55 43 / 0 0 0 70
ykm 47 29 49 36 / 0 10 10 50
hri 50 30 53 43 / 0 0 0 60
eln 45 28 46 34 / 0 10 10 50
rdm 48 23 54 39 / 0 0 0 70
lgd 43 30 50 35 / 0 0 0 80
gcd 45 28 52 36 / 0 0 0 60
dls 50 32 52 41 / 0 0 10 70


PDT watches/warnings/advisories...

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