376
FXUS66 KPDT 041708
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
908 AM PST Thu Dec 4 2025

.UPDATED AVIATION...18Z TAF...Sub_VFR conditions across TAF sites
except RDM/BDN/PDT. These conditions will remain through the
forecasted period with PDT/RDM/BDN seeing degrading categories
between 18-20Z. Rain is already at PSC/ALW/PDT and is expected to
affect RDM/BDN and SN/RA at YKM after 18Z. Winds will remain light
which is what will allow the FG/BR to continue and rain will
affect CIGs. CIGs will remain mainly below 3-5kft through the
period. 90


&&

.PREV DISCUSSION... /issued 836 AM PST Thu Dec 4 2025/

UPDATE...Light rain is continuing to pass through the Columbia
Basin, which has dissipated the earlier widespread fog impacting
the northern Blue Mountain foothills and the Yakima/Kittitas
Valleys. As a result, the Dense Fog and Freezing Fog Advisories
have been cancelled. There may still be some isolated pockets of
fog in low-lying areas and protected valleys, but the widespread
threat of visibilities less than 1 mile has diminished. 75

PREV DISCUSSION... /issued 349 AM PST Thu Dec 4 2025/

Updated for Aviation...

DISCUSSION...Fog still lingers throughout parts of the Foothills
of the Blues and Kittitas Valley through the rest of the morning.
Precaution should be given in areas of very dense fog and freezing
fog. Even given the stratus cloud cover, temperatures will
efficiently cool enough, thanks to light winds, to bring
saturation in many areas, especially the lower valleys, plumes of
fog through the night. We`ll continue to see temperatures drop
region wide to below freezing, with lower valleys have a bit
shorter on the confidence side that they`ll drop below freezing
and instead hover around the low to mid 30s (40-60% chance for
Valleys staying above freezing, and >85% chance for higher
elevations dropping below freezing). Otherwise, upper level dry
northwest winds will keep conditions dry for the rest of the
night. Unsettled weather continues later in the late morning hours
to early afternoon when a trough deepens in central Canada,
allowing shortwaves to form valley rain and snow/wintry mix in the
higher elevations.

We`ll have a constant stream of instability with surface southwest
flow, allowing a continuous stream of wetter/warmer weather
through the beginning of next week. Heaviest QPF amounts will be
located in the mountains, with three day totaling up to 3 inches
in the highest elevations (50-70 percent chance) with the lower
elevations that include the Basin, Central Oregon, and the
Kittitas Valleys seeing up to a quarter of an inch of rain, more
so than where the heaviest rain bands occur (40-60 percent
chance). A warm trend will begin on Friday with high temperatures
rising to low to mid 50s and continue on through next week as
well. This will cause some hydro and river level concerns going
through Wednesday with the snow falling between now and then,
although guidance at this time does not have some rivers going
beyond `Action` stage, it is something to keep an eye for the next
couple of days.

Breezy to windy conditions will be observed with the upcoming
system, with the strongest winds occurring between Friday night
and Saturday morning. Parts of the Columbia Basin, Foothills, and
other lower elevation areas will see gusts up to 30 to 40 mph for
much of the time. NBM advertising 40 to 60 percent chances of wind
advisory conditions over the weekend, with 10 to 30 percent
chances of gusts 57 mph or greater. No wind highlights expected
yet, but confidence is increasing slightly for Wind Advisory
thresholds, the question will be if they mix down enough to the
surface to exceed advisory thresholds.


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  42  38  54  41 /  90  80  90  50
ALW  42  38  51  42 /  90  90 100  70
PSC  41  36  53  41 /  80  70  70  20
YKM  41  32  51  39 /  50  50  70  50
HRI  43  38  55  43 /  90  70  80  30
ELN  42  34  46  35 /  60  60  80  60
RDM  46  37  56  34 /  50  50  70  30
LGD  39  35  49  39 /  90  90 100  80
GCD  41  37  48  36 /  80  90  90  50
DLS  47  43  56  47 /  80  80  90  80

&&

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

$$

UPDATE...75
DISCUSSION...95
AVIATION...90