Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 222342 AAA
AFDPDT

Area Forecast Discussion...Update
National Weather Service Pendleton OR
342 PM PST Thu Feb 22 2018

Updated Aviation Discussion

.SHORT TERM...Tonight through Saturday...Satellite shows an upper
level low located near the OR/CA/NV border that is sending
wraparound moisture into Wallowa County and the Northern Blue
Mountains. Upslope flow into Wallowa County will produce significant
snow (3-6 inches below 5500 feet and higher amounts in the Eagle
Caps) today through tonight. A Winter Weather Advisory has been
issued for this area. Snow will taper off early Friday morning as
the area will be between waves. The next wave will reach the
Cascades Friday afternoon with increasing clouds and snow. Snow will
spread across eastern WA and OR by Friday evening. Friday night
there will be likely snow in the mountains and a slight chance of
snow in typically rain shadowed areas. A reinforcing wave will move
through Saturday with more precipitation. In the Lower Columbia
Basin it may be mixed rain and snow but other locations will be
mainly snow. The mountains may see anywhere from 6 to 15 inches of
snow and perhaps 2 to 3 inches in Central Oregon Friday night and
Saturday so winter highlights are likely. Winds will become breezy
and increase to 15 to 25 mph Saturday afternoon. Temperatures will
remain well below normal. Coonfield

.LONG TERM...Saturday night through Tuesday night...Isolated to
scattered showers, mainly snow, look to linger over the region
Saturday night. Best chances would be over the mountains. Another
system still looks to be on track to move into and through the
region Sunday and Sunday night. This system should be accompanied by
a fair amount of wind with sustained speeds of 15 to 30 mph. This
wind will be from the southwest and west, and could lead to a
limited rise in snow levels and slightly warmer high temps. Isolated
to scattered showers, again mainly snow, look to occur Monday
through Tuesday due to a persistent and moist northwest upper level
flow. Another disturbance within the northwest flow then looks to
move into the region for widespread precip. Snow levels may rise a
bit Tuesday afternoon into Tuesday night. 90

Wednesday and Thursday...models develop an upper level low pressure
system off the British Columbia coast Wednesday. There are slight
discrepancies in track and strength but overall they are in good
agreement in their evolution and track of the low.  Zonal upper
level flow will become southwest as the system digs southward on
Wednesday. This will spread an area of precipitation over the entire
region. The system will continue to produce unsettled weather into
Thursday as it moves along the west coast of Washington and Oregon.
Daytime highs will continue to be below normal through the period
with snow levels hovering around 1000 feet in the northwest to
around 2000 feet in the south.  Earle

&&

.AVIATION...00z TAFs...Lingering upslope flow into central Oregon
will allow for MVFR cigs/vis with a few snow showers to persist at
KRDM and KBDN into the evening. These conditions should improve
gradually late tonight into early Friday morning. Elsewhere SCT-BKN
clouds with bases between 4000 and 7000 ft AGL will continue to
affect KDLS, KYKM, KPSC, KALW and KPDT. These clouds will dissipate
this evening at KYKM, KDLS and KPSC, and early Friday morning at
KALW and KPDT, as drier air moves over these sites. Mid and high
level cloudiness will increase Friday afternoon at most sites as the
next system approaches the region. Winds will generally run 5 to 15
kts through the period. 90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  16  36  28  39 /  10  10  40  60
ALW  20  37  30  42 /  10  10  50  60
PSC  18  38  32  45 /  10  10  20  30
YKM  19  36  26  45 /  10  10  30  30
HRI  17  37  31  44 /  10  10  30  40
ELN  17  35  25  40 /  10  20  40  40
RDM   9  34  24  37 /  10  10  30  70
LGD  15  30  25  34 /  40  10  50  80
GCD  14  30  25  33 /  20  10  40  80
DLS  21  38  32  45 /  10  10  50  60

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 PM PST this evening for ORZ050.

WA...None.
&&

$$

76/90/81/90


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