Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 182251
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
250 PM PST Sun Feb 18 2018

.SHORT TERM...Tonight through Wednesday...An upper level trough
continues over the region this afternoon with scattered to numerous
rain and snow showers occurring with some reports of small pea sized
hail. Also seeing the surface wind northerly flow pushing south
through Washington and now moving into northern Oregon. When this
flow begins to move into the higher terrain of Oregon we will begin
to see some enhanced upslope flow take place overnight leading to
some accumulating snowfall in some areas that have not seen much
snowfall since end of December. So, winter weather advisories have
been issued for the overnight period through early Monday. The upper
level trough will shift eastward Monday and be centered over the
northern Rockies. This will place the Pacific Northwest under the
cold dry northerly flow on the backside of the Monday through
Wednesday. Temperatures will be very cold during this period running
10 to 20 degrees below normal. Snow showers will taper off on Monday
and then remain dry through Wednesday.

.LONG TERM...Wednesday night through Sunday...Predominantly
northerly flow at mid/upper levels over British Columbia through the
extreme northerly latitudes in western Canada. Each disturbance will
transport modified arctic airmass into the forecast area for a
chance of mountain snow each day. Wednesday night and Thursday the
models bring a system through the region. Thursday night a brief
ridge of high pressure moves across the region. This will be
followed by a couple of shortwaves for unsettled conditions through
the weekend.
Polan


&&

.AVIATION...18Z TAFs...A mid/upper low will which is over the
Puget Sound this morning will move across the interior Pacific
Northwest today through this evening and then move into Idaho and
Montana overnight. Expect broken to overcast skies today becoming
scattered to broken late tonight. Ceilings will be 3500 feet and
above today with rain showers expected at all TAF sites. As colder
air moves into the area late this afternoon and evening rain showers
will turn to snow though amounts will be light. Snow showers will
taper off after 03Z. With the heavier snow showers, MVFR ceilings
and visibilities will be possible, otherwise low end VFR conditions
are expected tonight. West to southwest winds of 10 to 20 kts with
gusts to 25-30 kts today will turn more north to northwest late this
afternoon and tonight and gradually decrease.


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  22  26  11  30 /  60  20   0   0
ALW  21  25  12  31 /  60  20   0   0
PSC  22  31  14  34 /  30   0   0   0
YKM  22  30  13  32 /  20   0  10  10
HRI  22  31  13  34 /  40  10   0  10
ELN  18  28  11  28 /  20   0   0  10
RDM  18  25   4  31 /  60  20   0   0
LGD  16  17   4  24 /  60  30  10  10
GCD  17  19   4  25 /  70  30  10   0
DLS  25  33  16  35 /  60  10   0  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 9 AM PST Monday for ORZ502-503-
509.

     Winter Weather Advisory until 9 AM PST Monday for ORZ505-507-508-
     510-511.

WA...Winter Weather Advisory until 9 AM PST Monday for WAZ030.

&&

$$

91/99/99



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