109
FXUS66 KPDT 051208
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
408 AM PST Fri Dec 5 2025

.DISCUSSION...

Key Messages:

1. Breezy to windy conditions this afternoon through Saturday
afternoon. Wind advisories expanded both temporally and spatially.

2. Persistent rain chances through the next week combined with
high snow levels will lead to rises on area rivers.

Overview: The forecast for the next week can be succinctly
described as warm, wet, and windy as a subtropical high in the
Pacific combines with a remarkably persistent quasi-zonal to zonal
jet stream and multiple frontal systems to direct several rounds
of subtropical to tropical moisture into the Pacific Northwest.

Headline updates: The main update to headlines was the expansion
of existing wind advisories to include the Yakima Valley, Lower
Columbia Basin of Washington, and the Wallowa Valley.

Rain is beginning to overspread the forecast area again as low- to
mid-level warm air advection (WAA) associated with a warm frontal
passage this morning interacts with ample moisture. The result
will be the best precipitation chances for the lower elevations
through the remainder of the week. For mountain areas, especially
the Cascade crest and northern Blues, precipitation chances will
be more persistent into the weekend.

The main talking point today is the anticipated breezy to windy
westerly (southwesterly to northwesterly depending on the exact
location) winds that are poised to ramp later this afternoon
through tonight as a strong jet moves overhead. This afternoon
through Saturday morning, the 00Z HREF places a persistent 8-12
hPa pressure difference between PDX and GEG -- often the
threshold where advisory-level winds begin -- and an 850-hPa jet
of 40-60 kts over the Columbia Basin. While the largely nocturnal
nature of the event does reduce overall forecast confidence in
persistent, widespread advisory-level winds through the entire
advisory period, confidence is still high (70-95%) that peak gusts
will exceed 45 mph in wind-prone locations. Moreover, per NBM
calibrated probabilities, there is still a low-medium chance
(20-50%) of reaching or exceeding warning-level gusts in the most
wind-prone locations of the Columbia Plateau.

Snow levels today will remain high enough (generally 5-8 kft) to
preclude any concerns for winter weather headlines, though a
cooler air mass tonight through Saturday night will present lower
snow levels (4-5 kft) and at a medium chance (50%) of advisory-
level snowfall for White Pass. Through the bulk of the next week,
snow levels are then forecast to remain high at mostly 5-8 kft
with periodic dips to 4.5 kft along the Washington Cascades.

Lastly, will note a significant amount of precipitation is
forecast for the mountain areas Monday through Thursday of next
week. While confidence in precise amounts is still low, and will
depend on the exact location of the jet stream and incoming
frontal systems, the NBM places a 20-30% chance of reaching or
exceeding 5 inches of liquid equivalent across the Oregon Cascade
crest through the 72-hr period ending 4 AM Thursday, and an even
higher 40-50% chance for the Washington Cascades. Since much of
this precipitation is forecast to fall as rain, rises on area
rivers are anticipated. Current forecasts from the NWRFC in
Portland do place multiple rivers near or above action stage by
the latter half of next week.

&&

.AVIATION...12Z TAFS...Conditions were mainly ranged from VFR to
LIFR this morning, with BDN and RDM having VFR conditions and
ALW being socked in with low clouds and fog once again. ALl other
sites were generally either IFR or MVFR, mainly due to CIGS.

Latest radar showed an area of RA between DLS, PSC and HRI and once
this area moves through, additional RA is expected throughout the
day. Reduced CIGS/VSBYs are expected through the day everywhere
(and can`t be ruled out at BDN/RDM) until late afternoon, when
conditions should begin to improve.

Winds will increase during the mid to late afternoon hours from the
southwest to west and become gusty in the 25 to 35 kt range. These
winds will help clear out any fog and bring VFR conditions to all
TAF sites by evening/overnight. The only exception is ALW, where
some lingering low clouds may keep MVFR conditions longer, but
even that location should improve to VFR by late Friday
night/early Saturday.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  54  41  52  39 / 100  40  40  30
ALW  51  42  52  41 / 100  60  50  50
PSC  51  41  56  39 /  90  10  10  10
YKM  50  38  55  34 /  80  30  20  20
HRI  54  42  55  39 /  90  20  20  20
ELN  45  36  48  32 /  90  60  40  30
RDM  55  32  50  32 /  90  40  10  10
LGD  48  38  46  34 / 100  80  80  60
GCD  48  35  46  33 / 100  60  40  40
DLS  55  47  55  44 / 100  70  70  80

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 1 PM this afternoon to 10 AM PST Saturday for
     ORZ041-044-507-508-510.

     Wind Advisory from 1 PM this afternoon to 1 PM PST Saturday for
     ORZ050.

WA...Wind Advisory from 1 PM this afternoon to 10 AM PST Saturday for
     WAZ024-521.

     Wind Advisory from 7 PM this evening to 7 AM PST Saturday for
     WAZ026>029.

&&

$$

DISCUSSION...86
AVIATION...77