842
FXUS66 KPDT 102106
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
106 PM PST Mon Nov 10 2025

.DISCUSSION...

1. Breezy winds weakening late This Afternoon.

2. Mountain/foothills showers today, widespread Wednesday onward.

3. Pass level snow Thursday through the weekend.

Although local winds are not firmly in the wind advisory range,
breezy to gusty conditions will probably persist through the
middle of the afternoon in the Grande Ronde Valley as the surface
pressure gradient between Meacham and Baker is well agreed up by
the NAM and the NCEP SREF ensemble mean in the 6 to 6.5 range. A
significant weakening of the gradient looks imminent, and due to
the approaching surface cold front late early Today and passing
into SE OR and central ID this evening. Rain was occurring This
Afternoon along the cold front with probably some orographic lift
near KSMP with a broken band of rain extending into central and
northeast Washington. HREF PMMs show this activity spreading south
along the Washington into the Oregon Cascades this evening while
the eastern band develops southeastward dissipating across the
northern Blue Mountains. The mild temperatures forecast this
afternoon will be knocked down about 5 to 7 degrees in the
Columbia Basin for Tomorrows highs, following the cold front
moving though Tonight.

An AR will bring strong southerly 850 mb jet into central Oregon
with an IVT anomaly mid week, as a mid and upper level low
meanders onshore into western Washington Thursday night, lifting a
warm front northward across the region, setting up westerly flow
along the Cascade Caps. Pass level snow is possible for Santiam
Pass along US highway 20. The latest minor adjustments to the NBM QPF
and snow ratios/snow levels still produce about 6 inches total
snowfall over the pass area for a 2 day stretch Friday and
Saturday which is about an inch over the minimum for the local winter
weather advisory criteria. Additionally the White Pass along WA
highway 12 was coming in with an NBM mean of around 7+ inches near
the pass area, also above the lower bound for winter weather
advisory criteria. Snow load appears to be the more significant
impact as the snow ratios will be low, i.e. rain mixed with snow
and turning to all snow overnight Thursday night, with real
impacts for the pass levels by Friday morning. The snow levels
show large uncertainty to the the higher side as well, meaning the
outliers are on the side of less snow than more or longer
duration snow potential. Given the uncertainty and far out timing
at this point, its just a nod to the possibility for winter
weather advisories possibly being needed by mid to late week. At
this point the WSSI (winter storm severity index) is printing
minor impacts starting overnight Thursday and maximizing at 60%
chance of occurrence by midday Friday, which is inherently
unfavorable for any moderate impacts at all. Russell/71

&&

.PREV DISCUSSION... /issued 923 AM PST Mon Nov 10 2025/

UPDATED AVIATION...18Z TAFs...VFR conditions are forecast for
all sites through the forecast period. CIGs will lower through
the period as the front moves overhead, with a 20-30 percent
chance of light rain at DLS/PDT/ALW/PSC with chances of rain being
less than 20 percent at the remaining sites. MVFR CIGs are likely
late this afternoon into the overnight hours at PDT/ALW with 70%
confidence all other sites remain low in confidence for sub-VFR.
VIS will remain P6SM across all sites through the majority of the
period with only PDT/PSC seeing sub P6SM in the early morning
hours. Winds will be mostly 10 kts or less, with a few hours of
gusts forecast at DLS/BDN/ALW late morning and into the afternoon.
90



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  61  42  57  39 /  10  20   0   0
ALW  60  44  56  42 /  10  30   0  10
PSC  58  34  52  37 /  10  10   0  10
YKM  57  33  55  38 /  10   0   0  10
HRI  60  39  55  40 /  10  10   0   0
ELN  55  32  51  35 /  20   0   0  10
RDM  64  35  64  40 /   0   0   0   0
LGD  62  42  63  45 /   0  20   0   0
GCD  66  38  66  43 /   0   0   0   0
DLS  61  43  57  44 /  20  10   0  10

&&

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

$$

SHORT TERM...71
AVIATION...90