710
FXUS66 KPDT 051716
AFDPDT

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

.UPDATED AVIATION...18Z TAFs...BDN/RDM are at VFR and will continue
to see VFR conditions through the period. DLS/PDT/PSC/ALW are all
MVFR due to lower VSBYs 4-6SM due to BR and low CIGs below 3kft.
YKM sits at IFR due to very low CIGs below 700 ft and 4SM due to
BR. This will continue through 21-00Z as winds will pick up
across all TAF sits assisting with the push out of the fog and the
lifting of the CIGs.

A warm front will come across the region bringing with it
continued rainfall and an increase in the winds (80-90%
probabilities). Timing of the warm front crossing will be the
toughest part of the forecast, however, models show the front to
move across between 21-00Z. Wind advisories have been put out
across the many of the TAF due to winds nearing 30kts sustained
and 35-40 kt gusts. BDN/RDM will also see higher winds 10-20
sustained with gusts of 25-30 kt. With the assistance of the
winds, all TAF sites will see VFR conditions after 21Z (60-80%).
90


&&

.PREV DISCUSSION... /issued 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.



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  41  52  39  53 /  40  40  30  70
ALW  42  52  41  52 /  60  50  50  80
PSC  41  56  39  54 /  10  10  10  60
YKM  38  55  34  51 /  30  20  20  70
HRI  42  55  39  55 /  20  20  20  70
ELN  36  48  32  46 /  60  40  30  70
RDM  32  50  32  53 /  40  10  10  40
LGD  38  46  34  44 /  80  80  60  80
GCD  35  46  33  48 /  60  40  40  70
DLS  47  55  44  54 /  70  70  80  90

&&

.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...90