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000
FXUS66 KPDT 170635
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1035 PM PST Sun Feb 16 2020

.UPDATE...Light snow continues to fall along the east slopes of
the wa cascades especially along a narrow band from Easton to eln
that has prompted a winter weather advisory tonight. Meanwhile
isolated showers were developing across the region especially in
the blue mountains and minor accumulations can be expected here
overnight.

&&

.AVIATION...lcl mvfr conditions are possible at taf site kdls
while conditions could approach this at taf sites kpdt and kalw
in snow showers between 08z and 15z. Otherwise mostly vfr
conditions can be expected.

&&

.PREV DISCUSSION... /issued 640 PM PST Sun Feb 16 2020/

UPDATE...A weather system will track across the region tonight
and light snow will develop in the area mountains with several
inches expected in the blue mountains. Snow levels will lower and
snow showers are possible along the foothills of the blue
mountains into Monday morning. Meanwhile the snow showers will
extend into the john day highlands and also into central oregon.
Low temperatures are forecast in the mid 20s to lower 30s and the
short term forecast remains on track for now.

PREV DISCUSSION... /issued 105 PM PST Sun Feb 16 2020/

SHORT TERM...Tonight through Tuesday night...One system has
departed the region earlier this morning leaving just a few mountain
snow showers left over the CWA. There is a secondary piece of energy
that will swing down in the northwest flow aloft which will have
colder air aloft, therefore making the atmosphere more unstable and
the precipitation more showery in nature. Snow showers can be
expected in the mountains with rain showers in the lower elevations
of the foothills tonight and early Monday morning (Blues and Cascade
east slope). However, any accumulation looks to be light and under
advisory criteria. Looking at several inches perhaps in the
mountains and less than an inch elsewhere, if any. The basin will
likely stay dry with this system. This system will continue to
provide upslope rain and snow showers over the northeast mountains
on Monday night before ending on Tuesday. Then high barometric
pressure aloft will build over the region beginning late Tuesday and
persisting into the extended forecast period. Wind advisory for the
Kittitas valley this afternoon and early this evening looks good at
this time and will leave it going for now. 88

LONG TERM...Wednesday through Sunday...Models in good agreement for
the long term with quiet weather and a warming trend through
Saturday. Wednesday, a strong amplified ridge will be over the
PacNW. Ridge begins to shift east Thursday with the approach of a
dry front/trough that will pass over the region Thursday night into
Friday morning. Flow turns from zonal to more southwest on Saturday
with the approach of deep trough off the coast. Precip develops over
the Cascades Sat night as the upper trough/front works onshore with
snow levels 4-5 kft. Sunday looks to be wet and windy as the upper
trough moves inland and the front passes over the region, and models
are hinting that the air mass would be unstable with spring-like
convective showers. Colder air will spread east of the Cascades with
snow levels lowering to around 2K-3K feet late Sunday. Highs
Wednesday in the upper 30s to upper 40s, climbing to the upper 40s
to upper 50 on Saturday, then dropping slightly for Sunday behind
the front.

AVIATION...18Z TAFs...Mainly VFR conditions expected through the
period. Mountain snow showers through tomorrow afternoon with
mountain obscuration likely. SCT to BKN CIGs with varying bases AOA
4 kft with an outside shot of a shower or two, which could briefly
drop CIGS to MVFR, especially at PDT, ALW, RDM and BDN. Breezy winds
12-22g22-32 kts through this evening, decreasing overnight down to 6-
12 kts.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  30  44  23  45 /  30  20   0   0
ALW  34  46  26  47 /  50  20   0   0
PSC  33  49  28  48 /  10   0   0   0
YKM  29  49  24  47 /  10   0   0   0
HRI  33  49  26  48 /  10   0   0   0
ELN  26  43  21  42 /  60   0   0   0
RDM  25  44  19  46 /  20  10   0   0
LGD  28  37  17  38 /  70  30   0   0
GCD  28  39  17  42 /  40  40   0   0
DLS  34  49  28  50 /  20   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...Winter Weather Advisory until 4 AM PST Monday for WAZ026-520.

&&

$$

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