901
FXUS66 KPDT 012239
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
239 PM PST Mon Dec 1 2025

Updated Aviation Discussion

.AVIATION...00z TAFs...VFR conditions expected through the period,
with the exception of PSC which continues to deal with low cigs this
afternoon, and PDT/ALW, which may see light rain showers early
Tuesday morning from an oncoming frontal system. Confidence in the
latter two sites seeing measurable precip is on the lower end
(30-40%), so opted to mention the chance of -ra via prob30.
Otherwise, skies will gradually clear across most sites this
evening, with winds generally less than 10 kts, becoming more W/NW
Tuesday as this oncoming front moves through. 74

&&

.PREV DISCUSSION... /issued 233 PM PST Mon Dec 1 2025/

DISCUSSION...

Light snow is expected (40-90%) This evening through Tonight
across the Eastern Columbia Basin and foothills of the Blue
Mountains though the Northern Blues and Wallowas, creating winter
weather conditions. Lower elevations might only get a dusting or
more of snow but the snow amounts quickly ramp up with higher
elevations. A frontal system moving though This afternoon and
Tonight will be the initial strong orographic forcing impetus,
followed by persist northwesterly momentum behind the system
continuing to promote light precipitation in the dendritic growth
zone beyond 24 hours, driving high mountain areas well above 6
inches of snow with time. Latest HREF ensemble mean hourly trends
begin Northern Blue Mountains snow in earnest around 8z/or late
evening, with snow continuing through late afternoon Tuesday. For
Wallowa county  where 4 inches is the lower end for advisory,
snow chances for 4 inches or more below 5400 ft are quite low (20
percent or less across the majority of that area). The Northern
Blue Mountains of Oregon (OR502) have a higher minimum requirement
of 6 inches for advisories. In either case the probabilities for
this magnitude of snow is not meeting in 12 hours. One local
community with a greater risk of some snow imp- acts is Tollgate
where there is a 70% chance of 5 inches of total snowfall, and
about a 50% chance to hit or exceed the low end 6 threshold for
advisories.

Friday through the weekend look to be a windy period with
southwest winds increasing Friday evening, remaining windy
overnight and and not appreciably diminishing until Saturday
evening. Winds will pick up again diurnally Sunday, based on NBM
trends for this period. This change to a downslope windy regime
will lead to a more marked warmup on Friday where NBM is forcing
low to mid 50s across much of the Lower Columbia Basin, Blue
Mountain foothills, central Oregon and the John Day Basin.
Russell/71

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  29  40  27  40 /  20  60  10   0
ALW  30  38  29  38 /  40  70  10  10
PSC  25  39  24  37 /  20  30   0   0
YKM  24  45  24  38 /  10   0   0   0
HRI  27  41  26  38 /  20  40   0   0
ELN  25  44  22  37 /  10  10   0   0
RDM  26  46  21  46 /   0  10   0   0
LGD  31  41  27  41 /  40  90  20   0
GCD  30  42  27  43 /  10  50  10   0
DLS  34  51  34  43 /  10  20   0   0

&&

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

$$

DISCUSSION...71
AVIATION...74