488
FXUS66 KPDT 122348
AFDPDT

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

.UPDATED AVIATION.

.AVIATION...00Z TAFs...Rain showers are much more widespread in
the area than yesterday. Conditions remain mostly VFR in the near
term, with the exception of PDT experiencing IFR conditions
currently due to the passage of some heavier rain. Once this band
of rain pushes off to the east, conditions will improve soon
after. MVFR conditions with CIG and/or VIS impacts is expected at
most sites over the next 24-hours as the weather system continues
to bring some heavy rain at some sites along with cooler overnight
temperatures expected. Winds will remain less than 12 knots,
with the exception of gusts up to 25 knots expected at YKM/PSC
from tomorrow morning through the rest of the period.


&&

.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