405
FXUS66 KPDT 012233 CCA
AFDPDT

Area Forecast Discussion...corrected
National Weather Service Pendleton OR
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

&&


.PREV DISCUSSION... /issued 940 AM PST Mon Dec 1 2025/

AVIATION...18z TAFs...Low clouds and patchy fog continue for PSC
this morning, otherwise VFR conditions prevail across the forecast
area. Expect bkn-ovc cigs 7-10 kft throughout the day, with some
clearing early in the evening before the next frontal system
arrives by early morning Tuesday. IFR conditions may linger in PSC
over the next couple of hours, before seeing relief by the
afternoon. Not expecting precip with this next system across most
TAF sites, however PDT and ALW may see light rain showers
beginning at or just before sunrise, ending by the end of the TAF
period. Winds will generally be light and variable today, becoming
more W/NW overnight ahead of this next front. 74


&&

.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...99