649
FXUS66 KPDT 251724
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
924 AM PST Tue Nov 25 2025

Updated Aviation Discussion

.AVIATION...18z TAFs...An oncoming weather system will make for
another round of rain showers across most TAF sites starting early
this evening and lasting through early morning Wednesday. Only BDN
and RDM look to be spared from this system. Latest weather models
suggest precip will start at around 22z this afternoon for YKM,
extending to all other sites outside of central Oregon by 00z.
Precip type for YKM may be mixed with snow, but is expected to be
all rain elsewhere. Could see conditions drop to IFR this evening
and overnight for YKM, PSC, PDT, and ALW as a result of degraded
vsbys and low cigs. Rain is expected to be lighter at DLS, but
MVFR conditions are still possible. Precip is largely expected to
end between 10z and 12z, however moisture plus light winds are
expected to make for low cigs early tomorrow morning for most of
the aforementioned sites.

Overall forecast confidence is 80-90% for precip occurring outside
of BDN/RDM, 50-60% for IFR or worse conditions at the
aforementioned sites, and 40-50% for low cigs making for MVFR cigs
or worse early Wednesday morning, again for the aforementioned
sites where precip is most likely to occur. 74

&&

.PREV DISCUSSION... /issued 338 AM PST Tue Nov 25 2025/

DISCUSSION...

A surface trough and warm frontal system moves onshore this
morning spreading moisture over a slowly retreating high pressure
over the Interior Northwest. High confidence exists in surface
temperatures remaining at or below freezing through the duration
of the afternoon across the Washington Slopes and some of the
lower elevations in the Kittitas (60-100% chance even at peak
heating). NBM mean brings the valley into the mid 30s briefly this
afternoon. Light icing This Evening in the Kittitas valley is
possible, generally less than 0.05 based on NBM. FRAM freezing
rain accums model looks a bit more uniform in freezing rain
amounts of much less than 0.05. These are in the context of
probability of freezing rain being about 25% as they are balanced
with the snow levels and resultant snow probabilities. Road
temperature forecasts also support icing Tuesday evening through
the overnight. A start time for advisory messaging still looks
reasonable as the HREF LPMM hourly snowfall accums kick in around
9-10 am. The snow rates across the lower slopes look to be around
a one half inch per hour accumulation, and by midnight snow could
range as much as a foot on the crest to about half that at Cle
Elum, Expect some similar snows on the Blues and the Eastern
Mountains. Rain shadowing across the central Oregon is expected,
however wetting rain are likely (80 percent confidence) in the
Columbia Basin and foothills of the Blues while snow falls across
the higher elevations of the eastern Mountains. Warm advection
seems to win out after midnight and precipitation types flip back
to rain. Russell/71

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  45  37  47  35 /  50  90  60  60
ALW  44  39  46  38 /  50  90  70  70
PSC  43  34  44  37 /  50  90  40  60
YKM  41  31  44  35 /  70  90  40  70
HRI  43  36  45  37 /  50  90  40  60
ELN  38  29  41  32 /  80  90  40  80
RDM  48  34  53  29 /  20  40  20  10
LGD  45  34  46  34 /  40  90  70  50
GCD  47  36  51  34 /  30  70  30  20
DLS  44  39  48  41 /  70  90  60  70

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...Winter Weather Advisory until 4 AM PST Wednesday for WAZ026-522-
     523.

&&

$$

SHORT TERM...71
LONG TERM....71
AVIATION...74