Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 220522
AFDPDT

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

.SHORT TERM...Tonight and Monday...A cold front is exiting the
forecast area with just some lingering showers mainly over the
eastern mountains for the rest of tonight. A flat ridge of high
pressure will build over the region Monday but there will be one
last small shortwave attempting to pass over the region. This will
lead to a few more showers midday then coming to an end in the
afternoon and evening.

&&

.AVIATION...06Z TAFs...VFR conditions will prevail over the
next 24 hours although there could be some MVFR conditions near any
showers. Winds will generally be less than 10 KTs.


&&

.PREV DISCUSSION... /issued 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.



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  34  47  32  44 /  50  20  10  60
ALW  37  48  34  46 /  40  20  20  60
PSC  34  49  32  44 /  20  20  10  60
YKM  31  44  29  39 /  10  10  10  80
HRI  34  49  32  45 /  30  20  10  60
ELN  28  40  27  36 /  10  20  10  80
RDM  27  43  28  44 /  30  10  10  70
LGD  32  42  29  39 /  60  20  20  60
GCD  31  41  27  39 /  60  20  10  60
DLS  35  47  33  42 /  20  20  10  80

&&

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

$$

91/91/91



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