Pendleton, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

638
FXUS66 KPDT 162323
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
323 PM PST Tue Dec 16 2025

.DISCUSSION...A shortwave trough and attendant surface cold
front, currently offshore in the Pacific, will swing across the
forecast area overnight into early Wednesday morning. During this
period, 12Z HREF guidance suggests a low-level jet of 50-70 kts
coupled with a surface pressure difference of 10-18 mb between PDX
(Portland) and GEG (Spokane). This will drive a high wind event
across the majority of our forecast area, and High Wind Warnings
and Wind Advisories remain in effect from late this evening
through Wednesday. Strongest wind gusts of 70-80 mph are expected
along wind-prone portions of the Blue Mountain foothills and
slopes of the northern Blue Mountains. Of note, the Storm
Prediction Center (SPC) has placed the majority of our forecast
area under a Marginal risk of severe thunderstorms due to the
potential for severe outflow from low-topped convection with
frontal passage.

After frontal passage Wednesday morning, windy conditions are
forecast to continue through the afternoon hours, gradually
tapering off by late afternoon and evening as winds aloft weaken
and surface pressure gradients relax.

Along with the high winds, the cold front will facilitate a
transition from rain to snow for the mountains. Have opted to
issue additional Winter Weather Advisories for the Oregon
Cascades, northern and southern Blue Mountains, and lower east
slopes of the Washington Cascades due to the potential for near-
blizzard conditions characterized by moderate to heavy snowfall
rates coupled with blowing snow and low visibility with frontal
passage.

Looking ahead, another high wind event is possible Thursday as
winds aloft increase, but confidence is currently low-medium
(20-50 percent) in reaching High Wind criteria. That said, NBM
probabilities indicate better chances (40-70 percent) in reaching
Wind Advisory thresholds across most of our low-elevation zones.

Another concern Wednesday night through Friday is the potential
for winter weather and widespread precipitation as an atmospheric
river is directed into the Pacific Northwest. Will note there is
still ensemble variance in the axis and magnitude of that
precipitation, but the ECMWF EFI is highlighting most of central
to eastern Oregon with values of 0.8-1.0 for QPF, which indicates
good ensemble agreement in a climatologically significant event
for December. Low-elevation snowfall is possible with this system
(30-50 percent chance of measurable snow in central Oregon and the
Kittitas Valley, with higher chances of 70-90 percent in the
Grande Ronde Valley and John Day Basin), but current forecast
snow levels from the NBM quickly rise to 6-8 kft in Oregon and 3-5
kft in Washington Thursday in the wake of a warm frontal passage
which would limit duration of snowfall.

River Flood Watches and Flood Watches remain in effect due to
anticipated rising river levels through the week.

&&

.AVIATION...00Z TAFs...VFR conditions prevail with a cold front
approaching the area overnight tonight. This next set of unsettled
weather will bring high winds across the area, bringing some sites
up to 50 knot gusts in the early morning hours, then decreasing by
the late morning hours to early afternoon, albeit winds will
still be 25 to 35 mph in most sites. Embedded with this system
will be precipitation mainly in the form of rain, although VIS and
CIG conditions will remain in VFR. Turbulence is possible in the
overnight hours with wind shear guidance showing 40 to 60 knot
shear across most sites. A small chance (5 to 15 percent chance)
remains for some LLWS across all sites. An Airport Weather Warning
remains in effect for PSC from 1 AM to 5 AM Wednesday due to
elevated winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  40  50  35  55 /  90  50  20 100
ALW  41  52  38  55 / 100  60  20 100
PSC  42  53  37  54 /  90  20  20 100
YKM  38  50  33  45 /  90  30  30 100
HRI  42  52  36  55 /  90  30  30 100
ELN  33  43  30  40 / 100  50  40 100
RDM  32  44  28  56 / 100  50  50 100
LGD  36  48  31  45 / 100  90  30 100
GCD  36  49  30  50 / 100  80  50 100
DLS  43  49  38  49 / 100  60  70 100

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 10 PM this evening to 4 PM PST Wednesday
     for ORZ041-044-507-508-510-511.

     Wind Advisory from 10 PM this evening to 4 PM PST Wednesday for
     ORZ049-050-505.

     Winter Weather Advisory from 4 AM to 10 AM PST Wednesday for
     ORZ502-503.

     Winter Weather Advisory from 1 AM to 4 PM PST Wednesday for
     ORZ509.

WA...High Wind Warning from 10 PM this evening to 4 PM PST Wednesday
     for WAZ024-026>029-521.

     Flood Watch through Friday afternoon for WAZ522-523.

     Winter Weather Advisory until 10 PM PST Wednesday for WAZ522.

     Winter Weather Advisory from 1 AM to 10 PM PST Wednesday for
     WAZ523.

&&

$$

DISCUSSION...86
AVIATION...95