Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 212136
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
136 PM PST Sun Jan 21 2018

.SHORT TERM...Tonight through Wednesday. Cold front moving through
the region this afternoon. Low dew points earlier delayed the
onset of precipitation a few hours. Radar and surface observations
now show rain and higher elevation snow are fairly widespread. An
upper level jet is moving over the top of the front as seen on
satellite. This will likely result in some enhancement which
should maintain the precipitation into the evening before tapering
off overnight. The mountains will receive several inches of snow
accumulation. Locally breezy south winds will also continue into
the evening before diminishing overnight behind the frontal
passage. Cool onshore flow Monday as the upper low moves inland to
our north. This will bring snow showers to the Cascades and Blues
with mostly cloudy skies for the remainder of the forecast area.
Weak ridge Monday night with mostly cloudy skies. Another strong
upper low will be approaching the Pacific northwest Tuesday into
Wednesday. This system will have a good moisture fetch and will
result in a significant rain and mountain snow event. 94

.LONG TERM...Wednesday night through Sunday...Medium range models
are in good agreement bringing a surface cold front/mid level trough
axis across the interior Pacific Northwest Wednesday night, exiting
to the east on Thursday. Will continue likely to categorical PoPs
for the mountains Wednesday night, with chance PoPs for the lower
elevations as precip shadowing increases with W/NW flow in the wake
of the front. Thursday/Friday will feature NW flow aloft and weak
impulses crossing the region. As such, will use mainly chance PoPs
for the mountains, with slight chances for most lowland locations,
and mainly dry conditions for the Columbia Basin. Snow levels will
fall to less than 2000 feet Thursday/Friday, so any precip will
generally fall as snow. A stronger mid level wave will impact the
area Saturday for a round of rain and snow, with snow levels rising
to 2000-4000 feet. GFS/ECMWF both now depict ridging building across
the area for Sunday, so expect mainly dry conditions, except for
perhaps the east slopes of the WA Cascades where a few snow showers
will be possible. Slightly above normal temperatures can be expected
Thursday, cooling to near/slightly below normal for the weekend.

.AVIATION...00Z TAFs...VFR conditions will generally prevail fur the
next 24 hours. Low end VFR conditions with areas of MVFR will be
possible through the evening hours, as a band of precip moves east
across the area. The greatest coverage of precip will likely occur
at PSC/PDT/ALW until 03-06Z. Winds of 12-20 KT with gusts up to 30
KT will gradually diminish to 12 KT or less overnight.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  33  46  32  44 /  70  10  10  60
ALW  35  47  34  46 /  70  20  20  60
PSC  32  49  32  44 /  40  10  10  60
YKM  28  45  29  39 /  20  10  10  80
HRI  32  49  32  45 /  50  10  10  60
ELN  26  40  27  36 /  20  10  10  80
RDM  27  44  28  44 /  40  10  10  70
LGD  29  41  29  39 /  70  20  20  60
GCD  27  39  27  39 /  60  20  20  60
DLS  33  47  33  42 /  40  30  20  80

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 PM PST this evening for ORZ509.

     Wind Advisory until 10 PM PST this evening for ORZ049.

WA...Winter Weather Advisory until 10 PM PST this evening for WAZ520.

&&

$$

94/80/80



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