591
FXUS66 KPDT 061451
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
651 AM PST Sat Dec 6 2025

.UPDATE...Winds have generally decreased in magnitude such that
wind advisory thresholds are no longer being met across a broad
area. Therefore, have either cancelled or allowed the wind
advisories to expire on time at 7 AM this morning. Will note that
exposed ridges and other especially wind-prone locations will
continue to see advisory-level winds early this morning.
Otherwise, breezy, sub-advisory winds are forecast to continue
today.

&&

.PREV DISCUSSION... /issued 330 AM PST Sat Dec 6 2025/

DISCUSSION...

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

Key Messages:

1. Windy to very windy conditions this morning, then breezy to
windy this afternoon. Numerous Wind Advisories in effect.

2. Winter Weather Advisory in effect above 4000 feet for the
Upper Slopes of the Eastern Washington Cascades Crest through
this evening.

3. Breezy to windy conditions return Monday.

4. Ample precipitation through next Wednesday or Thursday combined
with high snow levels will lead to rises on area rivers.

Headline updates: No updates to headlines on this shift.


Precipitation is pinned to the Cascades and northern Blues this
morning with dry, windy conditions present across the lower
elevations. Snow levels are approximately 4500-6000 feet, lowest
across the Washington Cascades, but remain just too high for snow
at mountain pass levels. While temperatures are anticipated to
cool a couple degrees, they are also running a couple degrees
warmer than forecast by NBM, HREF, and REFS guidance, so thinking
snow totals for the Upper Slopes of the Eastern Washington
Cascades Crest will be lower than previously forecast. As such,
have adjusted wording in the Winter Weather Advisory to reflect
lower snow accumulations.

The main talking point today is the ongoing breezy to very windy
westerly (southwesterly to northwesterly depending on the exact
location) winds. A persistent 10-12 hPa pressure difference
between PDX and GEG and low-level jet of 45-65 kts have both been
in place overnight. Winds of 20-40 mph with gusts of 35-55 mph
have been observed across a broad swath of the Columbia Plateau,
and locally stronger winds have surfaced along exposed ridges. The
strongest winds should only last a few more hours as surface
pressure gradients and winds aloft gradually slacken, but
widespread breezy conditions are anticipated to continue into the
afternoon hours.

Lastly, will note a significant amount of precipitation is
forecast for the mountain areas Monday through Wednesday or
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 30-50% 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 50-75% chance for the Washington
Cascades. For the northern Blues, the chance of 3 inches of liquid
equivalent is 20-40%. 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. With that in mind, much of this
precipitation is forecast to fall as rain, and rises on area
rivers are anticipated. Current forecasts from the NWRFC in
Portland do place multiple rivers at action stage or minor flood
stage by the latter half of next week.

AVIATION...12z TAFs...VFR conditions expected through the period.
Gusty winds will have peaked by the start of the period, however
gusts will continue to waver in the 20-30 kt range for some sites,
namely PDT, PSC, ALW, and DLS. LLWS may be experienced at times for
these sites, however the expectation is that the worst of the LLWS
has passed. Skies will start out generally clear to start the
period, before sct-bkn high clouds gradually build in heading into
the evening. 74

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  51  39  53  44 /  40  30  90  60
ALW  51  41  52  45 /  50  40  90  70
PSC  56  40  53  44 /  10  20  80  30
YKM  54  35  51  37 /  20  30  90  30
HRI  56  41  54  44 /  20  30  80  50
ELN  48  33  45  35 /  30  30  90  40
RDM  50  33  54  38 /  20  30  50  40
LGD  46  34  43  38 /  70  50  90  90
GCD  46  33  47  39 /  50  40  80  60
DLS  55  45  54  48 /  60  80 100  80

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...Winter Weather Advisory until 7 PM PST this evening for WAZ522.

&&

$$

UPDATE...86
DISCUSSION...86
AVIATION...74