892
FXUS66 KPDT 110617
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1017 PM PST Wed Dec 10 2025

.DISCUSSION...Radar shows precipitation associated with the PacNW
atmospheric river still producing light showers across the
Washington Cascades. Rain will continue in this warm system for
the next 12 to 24 hours, with the heaviest rains pushing through
the slopes of the WA Cascades in the overnight to early morning
hours Thursday. Guidance shows an additional 2.4 to 6.3 inches of
rain in the WA Cascade crest (especially closer to the Snoqualmie
Pass area) through Saturday (25 to 75 percent chance). This will
continue to bring hydrology concerns with rivers along the Yakima
and Naches rivers through Friday with rivers rising to Minor
level, with Yakima at Horlick, Kiona, and Parker & Naches near
Naches expected to be in Moderate level. Rivers will greatly
improve going into the weekend with most banks going below the
flood stage. Kiona will see a slight lag in the crest that is
expected to occur through the early morning hours of Saturday.
Flood Watches will continue through Friday morning with Flood
Warnings across the flooded rivers being in effect until further
notice. Conditions will greatly dry out Friday through Saturday.

Our next major focus is the wind threat bringing breezy/windy
conditions across the Basin, Simcoe Highlands, and North Central
Oregon in effect until 7 AM tomorrow morning. Observed winds
showed 70-80 mph gusts at Rattlesnake and other parts of the
Hanford Reach area, so went ahead and upgraded the advisory for
the WA Basin to a High Wind Warning through the time of the
original advisory. Other parts of the WA Basin are observing gusts
up to 55 mph with sustained 30 to 40 mph. Winds are expected to
be at their peak currently and will decrease in strength going
through tonight and the overnight hours. By tomorrow afternoon,
winds will drop to 15 to 25 mph area wide (65 to 85 percent
chance).

Our next weather system will occur through early next week with
upper level southwest flow bringing in moisture advection into
the area embedded with a shortwave to bring a relatively colder
system than the one we`re seeing today. Low valley light rain is
expected to take place with mountain snow showers expecting to
develop Tuesday with snow levels dropping to 4000 to 5000 feet (30
to 50 percent chance). We`ll see a slight cooling trend going into
early next week, with temperatures dropping from mostly the 60s
into the low to mid 50s, but low temps will stay above freezing
for most of the highly populated communities (35 to 55 percent
chance).

AVIATION...06Z TAFs...VFR conditions are forecast through the
period for all sites. While there is a chance of temporary MVFR
CIGs and light rain at DLS/PDT/YKM/PSC/ALW later tonight into
Thursday as moisture associated with an ongoing atmospheric river
(AR) sags southward, confidence is low (10-30 percent).
Southwesterly to westerly winds of generally 10-20 kts accompanied
by gusts of 20-30 kts, except 20-30 kts with gusts of 35-45 kts
at PSC, will continue overnight. Anticipating PDT will transition
from light southeasterly to breezy southwesterly overnight, but
confidence in timing is low. Have included a mention of low-level
wind shear (WS) at PDT/ALW/PSC due to a 45-55 kt jet around 2 kft
AGL. WS and surface winds will diminish by Thursday morning as
winds aloft decrease.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  51  60  43  59 /   0  10  10   0
ALW  54  58  48  58 /  10  20  30  10
PSC  55  62  44  57 /   0  10  10   0
YKM  48  59  41  58 /  20  10  10   0
HRI  53  62  45  58 /   0  10  10   0
ELN  44  52  39  53 /  30  20  30  10
RDM  37  59  31  59 /   0   0   0   0
LGD  45  55  41  57 /   0  20  20  10
GCD  39  56  36  56 /   0   0  10   0
DLS  55  60  47  59 /  50  20  30   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory until 7 AM PST Thursday for ORZ041-044-507-508-510.

WA...Wind Advisory until 7 AM PST Thursday for WAZ024-027-029-521.

     Flood Watch through Friday morning for WAZ026-027-521>523.

     High Wind Warning until 7 AM PST Thursday for WAZ028.

&&

$$

DISCUSSION...95
AVIATION...86