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000
FXUS66 KPDT 210557 AAA
AFDPDT

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
956 PM PST Sun Jan 20 2019

Updated aviation discussion

.UPDATE...An upper trough over the Pacific Northwest continues to
move east. One wave mainly to our northeast continues to send
upslope snow and rain showers into the Blue Mountains and Blue
Mountain Foothills. The snow showers in the Blue Mountain
Foothills are weakening on radar as the wave pulls away but
should continue for a few more hours. Snow has been sticking in
places but do not expect more than an inch and generally less than
that. Snow will continue in the mountains most of the night and
anticipate 1-2 more inches. Meanwhile moisture continues to
stream around the base of the trough into central Oregon. A chance
of light snow will result overnight in central and north central
Oregon but amounts will be less than an inch. With abundant low
moisture, fog is a possibility and low clouds and reduced
visibility is already present in many locations. Have kept patchy
fog and freezing fog in the Columbia Basin, down through north
central and central Oregon to Bend and up through the Interstate
90 corridor to Snoqualmie Pass. Made changes to pops, weather and
precipitation and snow amounts. Forecast update already out. Perry

&&

.AVIATION...06Z TAFs...A system has moved out of the area though
light snow showers continue from the Blue Mountain Foothills
eastward. Showers should end at KPDT in the next few hours and by
12Z at KALW. Snow will continue into tomorrow morning in the Blue
Mountains and Wallowa county. As the trough trailing behind crosses
the area a southerly flow into central Oregon will lead to
occasional light snow showers at KRDM and KBDN through 09Z tonight.
As precipitation ends, low level moisture will promote low clouds
and visibilities tonight and have IFR/LIFR conditions at all TAF
sites except for MVFR conditions at KDLS and KPSC. Conditions will
improve tomorrow and skies will be mostly clear after 21Z except at
KALW and KPDT where MVFR ceilings are expected in the afternoon. Low
clouds and fog may return to those two TAF sites after 03Z. Winds
will remain below 12 kts for the next 24 hours. Perry

&&

.PREV DISCUSSION... /issued 148 PM PST Sun Jan 20 2019/

SHORT TERM...Shield of steady rain and snow across northern OR
and southern WA will become more showery and upslope in nature
this evening as the surface low and cold front works into ID/MT
and the upper-level trough pushes onshore. Lowering snow levels
across the region through tonight, but any accumulations in the
valleys will be minor. Precip will end northwest to southeast
tonight into tomorrow as the upper-level trough pushes east. Storm
total snow accumulations of 1-3 inches around 2000 to 3500 feet
in central and northeast Oregon with 3-7+ inches possible in the
east slopes of Cascades, Simcoe Highlands, Blues, Strawberries,
Elkhorns and Wallowas. Weak ridging should bring dry weather over
the CWA tomorrow night but will quickly shift south and east by
Tuesday morning. Moist NW flow then sets up and a combo of
progressive short wave troughs will drop through the flow into the
PacNW Tuesday and Wednesday. Wednesday`s system looks to be a bit
stronger/wetter. Snow levels will rise from 1500-3000ft Tuesday
to 4000-5500ft Wednesday. Mountain locations will see the brunt of
precip as the lower valleys and basins will likely be more
shadowed from the Cascades with this type of storm track. Winds
could be breezy Tue and Wed, especially Wed as stronger winds
aloft mix down along and behind the front. There could be some
fog/freezing fog formation tonight and again tomorrow night due to
abundant low level moisture with the recent precip and partial
clearing skies above developing inversions in the lower valleys and
basins. Warming trend through the short term with highs tomorrow in
the 30s to low 40s becoming very mild by Wednesday with highs in the
mid 40s to 50s. Lows tonight in the mid 20s to low 30s, dropping
tomorrow night into the mid teens to near 30, becoming mild Tuesday
night in the upper 20s to near 40.

LONG TERM...Wednesday night through Sunday...A few showers may
linger over the mountains as an upper level disturbance moves east
into MT. Thursday an upper level ridge will build offshore and
persist through at least Saturday. This will create dry conditions
with late night and morning fog. Models are inconsistent with the
breakdown of the ridge Sunday. An upper level low and associated
trough will move from AK to MT Sunday but the models are
inconsistent in how the southern end affects eastern WA and OR.
Temperatures will be quite mild with highs in the mid 40s to lower
50s.  Coonfield

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  30  39  28  42 /  60  10   0  30
ALW  32  39  31  44 /  70  10   0  20
PSC  32  43  32  44 /  50   0   0  20
YKM  27  41  27  40 /  20   0   0  20
HRI  31  43  31  45 /  60  10   0  30
ELN  26  38  26  38 /  10   0   0  30
RDM  26  39  23  42 /  40  20   0  30
LGD  31  37  23  38 /  30  20   0  30
GCD  31  37  23  40 /  30  20   0  30
DLS  33  44  32  42 /  20   0  10  50

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&

$$

83/76/83