342
FXUS66 KPDT 092135
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
135 PM PST Sun Nov 9 2025

.DISCUSSION...

Key Messages:

1. Breezy winds today through Monday morning.

2. Mountain showers Monday, widespread late Wednesday.

3. Pass level snowfall Thursday through Saturday.


High Pressure continues to influence the weather across the
Interior Northwest This Afternoon. Windy conditions are persisting
across the Grande Ronde Valley as gusts may occasionally hit
around 35 mph this afternoon, and given the values of the pressure
gradient (5-6 mb averaging between NBM and the SREF) across the
Baker to Meacham areas, the values uptick to around 6 mb
differential by the overnight, keeping winds strong through Monday
morning. An upper level ridge at 500 mph will slide east Tonight,
allowing a return to more zonal flow aloft across the area for
Veterans Day and Tuesday. The pattern will promote dry,conditions,
mild temperatures in the 50s and 60s. Some instability/orographic
lifted showers can occur along the Cascade crest Monday, however
the real uptick in rain and snow chances does not begin until
about midweek when the initial moisture advection associated with
the next atmospheric river is realized. Timing of best moisture
transport in overnight Wednesday through the day Thursday. Snow
levels remain quite high at around 6,000 ft or higher through
about Thursday afternoon before crashing Thursday night and
falling to around 4000 ft or less by early Friday morning across
the Cascades. NBM snow totals for the Thursday to Saturday period
do show potential for advisory level snow amounts at Santiam and
White Pass areas (as much as 6 inches, about a 50% chance by
Sunday Morning) and less at considerably less Snoqualmie Pass. The
warmer regime would also imply a wet snow as the NBM snow ratios
are only around 8-9:1 over most of this forecast zone. WSSI -P
(probabilistic winter storm severity index) gives a 40% chance for
minor impacts along the highway 12 section near white pass and
highway 20 sections near Santiam on Thursday, attributable to
snow load and snow amount a lesser degree. Russell/71


&&

.PREV DISCUSSION... /issued 942 AM PST Sun Nov 9 2025/

AVIATION...18Z TAFs...Mostly VFR conditions expected through the
period. Low and patchy fog developed overnight and lead to less
than IFR conditions developing at site PDT this morning, with fog
staying west of site ALW and east of site PSC. Fog is lifting in
these areas as of writing this. A weak system moving into the
region tonight will keep chances of fog low (<15%) across much of
the area, with about a 15-30% chance of MVFR CIGs developing at
site DLS, with less than 15% chance elsewhere. Otherwise, CIGs
will generally remain above 15kft AGL through tomorrow morning.
Winds will be light, 12kts or less, through the period. Lawhorn/82

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  37  62  40  56 /   0  10  10   0
ALW  42  61  43  56 /   0  10  20   0
PSC  36  57  35  53 /   0  10   0   0
YKM  37  57  32  55 /   0  10   0   0
HRI  37  59  39  55 /   0  10   0   0
ELN  34  57  33  52 /   0  20   0   0
RDM  36  65  34  62 /   0   0   0   0
LGD  42  62  41  61 /   0   0  10   0
GCD  39  66  37  65 /   0   0   0   0
DLS  42  61  41  57 /   0  20  10   0

&&

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

$$

DISCUSSION...71
AVIATION...82