214
FXUS66 KPDT 130547
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1047 PM PDT Sun Oct 12 2025



.UPDATED AVIATION.


.AVIATION...06Z TAFs...Rain showers continue to impact most sites
with low cloud decks of around 4000-5000 feet. Some of the heavier
bands gave some sites brief MVFR/IFR conditions. At least a small
chance remains through the night for all sites (5-15% chance) for
brief MVFR/IFR conditions with the heavier bands of rain occur.
As temperature drops overnight, we can expect some areas to
approach at/near saturation with light winds. This could produce
VIS and CIG issues in some areas. Confidence is not high for
widespread/longevity sub-VFR conditions, so PROB30 groups for
MVFR have been put in for PDT/ALW for the early morning hours
tomorrow. DLS/RDM/BDN will see MVFR conditions thanks to lowering
cloud decks of around 2500 feet.



PREV DISCUSSION... /issued 202 PM PDT Sun Oct 12 2025/

.DISCUSSION...

Broader forcing for lift becomes realized this evening and
maximized through the overnight period as the upper trough pivots
south along the NW Pac coastline, creating weak moist advection
this evening followed by CAA and an upper axis of deformation
into Monday morning. HREF 24 hr QPF indicates broad areas of one
tenth to one quarter inch of wetting rains across the more
elevated areas east of the Cascades and over the Columbia
Plateau, and under one tenth (wetting) in most of the more low
lying basin regions, as well as several inches of snow in the
highest elevation like Newberry/Paulina Peak, Three Sisters and
the Eagle Caps. As for the large fires in Washington, the HRRR
valid for 12z Monday would bring about one quarter of an inch
(QPF) across the Wildcat perimeter and about a half an inch
across the Labor Mountain fire (mostly in the p-type of snow). The
lower elevation Snoqualmie Pass may be less impacted than snow of
the higher elevation passes. For the overnight widespread cloud
cover, and minor upward adjustment on overnight lows by hedging
toward the higher NBM minimum T members. Both Washington and
Oregon eastern upper slopes forecast zones continue to have a
winter weather advisory for snow for Tonight and about the first
half of Monday.

Late Monday should bring clearing from the NW to the SE as the
upper low meanders into Nevada. That clearing and trending light
winds will create the coldest air of the season locally and
should result in a killing freezing for the Kittitas valley by
Tuesday morning. Temperatures recover by mid week into the 60s
over most of the lower elevation areas, a trend that seemingly
maxes out by Saturday before the next organized precipitation
maker arrives. That next period of precipitation is being flagged
by the NBM ensembles, centered around next Saturday and Sunday.
At this point, low confidence exists as models can significantly
change, however currently the members are pointing to another
round of mountain snows (up to 80% chances). This appears to be a
heavily rain shadowed episode as well, given that max percentages
for rain in excess of one tenth of an inch is only up to 20
percent in the Interior Northwest. Russell/71

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  41  58  34  55 /  90  50  10  10
ALW  44  60  37  55 /  90  40  10  20
PSC  42  61  36  59 /  80  50   0  10
YKM  39  54  35  60 /  90  80   0   0
HRI  42  60  36  58 /  80  50   0  10
ELN  33  53  29  59 /  90  80   0   0
RDM  30  49  26  51 /  80  60  20  10
LGD  38  55  35  56 /  80  50  20  30
GCD  39  54  34  57 /  90  60  20  30
DLS  44  56  40  62 /  90  60  10  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 1 PM PDT Monday for ORZ509.

WA...Winter Weather Advisory until 1 PM PDT Monday for WAZ522.

     Freeze Watch from Monday evening through Tuesday morning for
     WAZ026.

&&

$$

SHORT TERM...71
LONG TERM....71
AVIATION...95