512
FXUS66 KPDT 161011
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
311 AM PDT Thu Oct 16 2025

.DISCUSSION...Today through Saturday Morning: Dry conditions will
persist through this evening as weak ridging will move across the
PacNW as an upper low to the south pushes into the Rockies. By
tonight, a shortwave with an attendant cold front will arrive to
the PacNW, but will only clip WA and northern OR as it moves
across the region through Friday. Light rain showers will develop
along mainly the WA and northern OR Cascade crest with snow
showers mainly above 6.5kft. The cold front approach tonight and
subsequent passage tomorrow will result in breezy west to
northwest winds through the Cascade gaps (gusts around 30-40 mph)
and the Columbia Basin (gusts around 25-35mph). There is moderate
confidence (50-65%) that localized areas of the Kittitas valley
may see sustained winds around 30 mph with occasional gusts
between 45-50mph late tonight and tomorrow afternoon. That said,
confidence is too low to issue any wind highlights for the valley
at this time.

Dry conditions with light winds will briefly return to the
forecast area late Friday through Saturday morning as an upper
level ridge pushes across the PacNW.

Saturday Afternoon through Monday: By Saturday afternoon,
ensemble guidance is in great agreement of an upper low dropping
out of the Gulf of Alaska, then passing over the PacNW Sunday into
early Monday with widespread chances of rain showers and light
mountain snow above 5kft. Chances of snow amounts greater than 2
inches will generally be between 35-70% across the Cascade crest,
interior northern Blues, and along the Elkhorns. As for rain
amounts, there is a 45-80% chance for 0.75 inches along the
Cascade crest/upper east slopes as well as around Tollgate and
areas to the north in the Blue Mountains; a 30-60% chance for 0.5
inches in the remainder of the northern Blues and across Wallowa
county; around a 35-70% chance for 0.25 inches across the
remainder of the eastern mountains and portions of north central
Oregon. As for the lower elevations, chances of 0.1 inches will
range from 55-75%. Confidence is mod-high (60-85%) that a pressure
gradient developing across the Blue Mountains will result in
breezy south winds (gusts 25-40mph) developing through the Grande
Ronde Valley and north-south oriented canyons/valleys across
Wallowa county throughout Saturday night as the trough
approaches. Otherwise, the incoming upper trough will bring breezy
west to southwest winds through the Columbia Basin Sunday
(confidence 70-85%).

There is good agreement amongst ensemble guidance that upper
level ridging will build back over the PacNW with mostly dry
conditions and lingering light showers across the Cascades and
portions of the northern Blues Monday.

Tuesday through Wednesday: Moderate confidence (45-60%) that
upper level ridging will persist over the region, but will briefly
flatten as a shortwave crosses into southern BC early Tuesday.
Light showers along the WA Cascade crest will be possible, but
with a stronger shortwave the northern OR Cascade crest may see
light showers as well. Good agreement amongst ensemble members in
ridging building back over the PacNW with mostly dry
conditions(confidence 40-60%), though disagreement grows in
whether weak shortwaves riding up the backside of the ridge will
continue to bring light showers to the Cascades Wednesday.
Lawhorn/82

&&

.AVIATION...Previous Discussion...06z TAFs...VFR conditions
expected. Sites are expected to mostly see skc through the night,
outside of some low clouds that may develop around BDN/RDM in the
early morning, as they have over the last few nights. Sct-bkn mid
to high cigs will then build in tomorrow afternoon across all
sites. Winds will remain light and terrain-driven. 74


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  62  39  65  35 /   0   0   0   0
ALW  61  44  64  40 /   0   0   0   0
PSC  62  37  67  34 /   0   0   0   0
YKM  64  38  66  34 /   0   0   0   0
HRI  63  39  66  35 /   0   0   0   0
ELN  62  37  60  31 /   0   0   0   0
RDM  63  29  64  27 /   0   0   0   0
LGD  62  34  63  31 /   0   0   0   0
GCD  61  34  64  32 /   0   0   0   0
DLS  66  44  66  40 /   0   0   0   0

&&

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

$$

DISCUSSION...82
AVIATION...74