Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 151101
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
250 AM PST Fri Dec 15 2017

.SHORT TERM...Today through Sunday...An upper level trough will move
through the region today and tonight bringing a cold front with it.
A pool of cold air with temperatures below freezing will be in the
lower Columbia Basin this morning and into the afternoon presenting
the risk of freezing rain. As such a Winter Weather Advisory for
freezing rain is in effect today for freezing rain in the Foothills
of the Blue Mountains of Washington ang the northern Blue Mountain
Foothills of Oregon. the trough will exit the regiopn overnight with
snow decreasing in the eastern mountains by daybreak. High pressure
then builds over the region.  Polan

.LONG TERM...Sunday night through Friday...The pattern will remain
unsettled during the extended period with a progressive flow pattern
of troughs and ridges moving through the CWA. The troughs will each
bring a chance of lower elevation rain and mountain snow while the
ridges bring some break in the precipitation. However the moisture
will still flow over the ridges into the CWA for mainly mountain
snow showers. The models are in fair agreement through the extended
period. On Sunday night and Monday a flat upper ridge will be
situated off the coast with moisture flowing into the CWA...bringing
precipitation mainly to the mountains. There will be a rain
shadowing effect along the Cascade East slopes and the Basin. An
upper trough will then swing down from the Gulf Of Alaska bringing
cooler air with a better chance of mountain rain and snow by Tuesday
and Wednesday. After that an upper ridge will move in behind it for
Thursday and Friday with a drying trend and cooler conditions. The
models have backed off on the amount of cold air coming in late in
the extended period...but if there is any precipitation there may be
snow as low as the Blue Mountain Foothills. Models remain in good
agreement in the late extended period. Winds will remain light
through the extended period. 88

&&

.AVIATION...12Z TAFs...MVFR and IFR conditions will be possible at
all TAF sites through the next 24 hours with low stratus and patchy
freezing fog. There may be some freezing rain or snow today as a
weather system moves through the area. This system will help to mix
out the low clouds and fog...but it will take a stronger system to
completely mix out the lower valleys and basins. Winds will be light
through the next 24 hours. 88

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  31  29  39  31 /  80  40  10  10
ALW  33  31  41  33 /  80  60  20  10
PSC  33  30  42  32 /  60  20  10  10
YKM  32  27  41  30 /  10  10  10  10
HRI  33  29  41  32 /  70  20  10  10
ELN  33  28  37  30 /  20  10  10  10
RDM  46  22  38  24 /  30  20  10  10
LGD  35  29  35  25 /  60  50  20  10
GCD  43  28  37  28 /  40  50  20  10
DLS  38  36  45  36 /  40  10  20  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Air Stagnation Advisory until 10 AM PST this morning for ORZ041-
     044-050-505-507>511.

     Winter Weather Advisory from 10 AM this morning to 7 PM PST this
     evening for ORZ507.

WA...Air Stagnation Advisory until 10 AM PST this morning for WAZ024-
     026>029-520-521.

     Winter Weather Advisory from 10 AM this morning to 7 PM PST this
     evening for WAZ029.

&&

$$

99/88/88



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