Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 032322 AAA
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
320 PM PST Sat Dec 3 2016

updated the aviation discussion

.SHORT TERM...Tonight through Tuesday...A shortwave trough embedded
in northwest flow aloft will drive a cold front across the region on
Sunday. This will usher in much colder air that will last through
much of next week. There will be chance to categorical probabilities
of rain and mountain snow with this system later tonight and Sunday
before things dry out a bit Sunday night. Snow levels will start out
at 3000-4500 feet tonight then by Monday lower to near the basin
floor. It will also become windy Sunday across the lower elevations
with gusty west winds. There may be a potential need for low end
wind highlights Sunday across the Kittitas Valley.

Have issued a Winter Storm Warning for heavy snow for the Northern
Blue Mountains of Oregon and Southeast Washington for tonight
through Sunday evening for 8 to 12 inches of snow mainly above 4000
feet. Leaned on the NAM a little more than the other models since
this will be a partially upslope driven event and the NAM tends to
perform well in these situations. Another trough will move across
the region on Monday and Monday night with a chance for snow
showers. The models are having a difficult time pinpointing where
the precipitation will focus though all seem to agree that most of
it will be fairly light. With the trough tending to dig into central
Oregon and northerly upslope flow...there could be some enhanced
snowfall over the Deschutes Plateau and east slopes of the Oregon
Cascades. By Tuesday just about all areas will be below freezing for
high temperatures although it could nudge just above freezing in the
eastern Columbia River Gorge.

.LONG TERM...Tuesday night through Saturday. High pressure will
build across the two state area and drier conditions can be expected
during the middle of the week. Meanwhile a storm system will
approach our area Wednesday afternoon and light snow may develop
along the wa/or cascades late Wednesday afternoon/evening before
rapidly spreading east into the remainder of our area Wednesday
night. Cold air remains in place and light snow should continue into
Thursday and significant snow accumulation are possible. The
confidence is increasing for accumulating snow and another challenge
is the possible advection of some warmer air into portions of the
area Thursday afternoon and night. The exact timing and location of
any warmer air remains uncertain and despite the intensity of the
pcpn lessening...showers should persist into Friday as another low
pressure system sweeps through the region. Some drier conditions
could slowly return Saturday as a ridge of high pressure attempts to
build into the region but showers should linger especially in the
area mountains.

&&

.AVIATION...00Z TAFS...vfr conditions will persist across all taf
sites into tonight. A low pressure system will bring clouds to the
region after 02z and these will lower into Sunday morning when lcl
mvfr conditions could be approached at all taf sites after 08z in
and near showers. In addition brief wind gusts to 25 kts could occur
at taf sites kpdt...kalw...kpsc...kdls until 02z. Then a return to
brief wind gusts to 25 kts is again possible after 18z tomorrow for
taf sites kykm...kdls...kpdt...kalw.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  38  43  26  34 /  20  70  30  30
ALW  41  45  28  38 /  40  90  30  30
PSC  42  48  26  38 /  10  40  10  40
YKM  33  45  21  36 /  10  20   0  30
HRI  39  47  27  39 /  10  40  10  30
ELN  33  39  20  33 /  20  30  10  30
RDM  33  43  21  38 /  20  60  20  40
LGD  34  38  20  31 /  50  80  30  30
GCD  33  38  13  32 /  20  70  40  40
DLS  40  46  30  40 /  20  60  10  40

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning from 10 PM this evening to 10 PM PST Sunday
     for ORZ502.

WA...Winter Storm Warning from 10 PM this evening to 10 PM PST Sunday
     for WAZ030.

&&

$$

78/97/97


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