270
FXUS66 KPDT 161121
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
321 AM PST Sun Nov 16 2025


Key Messages

- Precipitation Today though Monday

- Another system may affect the region Thursday Through Saturday

- Temperatures at or above normal through the week



.DISCUSSION...

Fog or low stratus was forming west of DLS based on GOES
satellite, as visibility possibly reduced locally in fog along
the rest of the lower lying Columbia basin to the east. Pasco
dropped to around 2 miles seemingly in step with the LAMP
guidance. A mild day in store for the region is expected however
not near as warm as yesterday as the cold front is moving in and
clouds and possibly  even late day rain cooled air will cut the
highs by roughly 10 degrees to the low and mid 50s over most of
the area. Breezy to windy conditions are anticipated in the Grande
Ronde Valley where the chances for gusts in excess of 25 mph is
upwards of 70%. Likewise stronger gust on the Eastern Slopes of
the Washington Cascades and the Columbia Gorge where these same
probabilities are 90% and up. An amplified mid and upper level
trough and well defined baroclinic leaf on satellite was moving
toward the PacNW as the system brings IVT values of less than 500
orientated nearly parallel to the coastline and Cascades. Ahead of
this approaching trough system is a low pressure over CA/NV that
will spread rain showers northward into the eastern Mountains late
Tonight through early Monday. NBM mean values for QPF average
around one quarter of an inch on the broad scale to as much as
three quarters of an inch at the highest peaks of the eastern
Mountains through about midnight or 12am Monday. Forecast
confidence is high with this episode as the higher terrain areas
have probabilities of precipitation ranging between 70-95%, while
the more lowland areas across the Columbia Basin to Central Oregon
average 40 to 50% chances through the late afternoon and evening
hours. The snow levels will again will be quite high and above
6000 ft for these areas through at least Tuesday morning.
Occasional brief showers will linger across the region on Monday.
Relatively mild conditions persist through the end of the 7 Day
period with a generally cooling trend. GFS and ECMWF show another
similar system coming in around the 114 hour timeframe, around the
20th/Thursday. A cursory glance at the ESAT shows if anything
this system is slightly anomalously warm for the time of year.

&&

AVIATION...06Z TAFs...Clearing skies this evening will transition
to mostly cloudy to overcast skies tonight through the remainder
of the valid period as ample moisture accompanies a pair of
weather systems. Confidence is low-medium (20-60 percent) in some
mist and fog formation overnight, with the best chances at
DLS/ALW/PSC. Sub-VFR CIGs/VSBYs in rain late Sunday morning
through Sunday evening will be possible (20-50 percent chance at
DLS/RDM/BDN/YKM/PSC and 60-80 percent at PDT/ALW), but confidence
is still lacking on exact timing/location of the incoming band of
rain so have not advertised sub-VFR conditions (aside from the fog
potential overnight into Sunday morning) in the 06Z TAFs. Winds
of 10 kts or less are forecast for the next 24 hrs.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  53  43  56  39 /  70  80  50  30
ALW  53  46  56  43 /  80  90  60  50
PSC  54  44  56  40 /  50  60  30  20
YKM  58  43  57  38 /  20  40  20  20
HRI  53  44  56  41 /  60  60  30  20
ELN  55  40  53  35 /  30  50  30  30
RDM  57  36  54  30 /  40  50  40  10
LGD  54  43  56  38 /  90  90  70  50
GCD  54  42  56  35 /  90  90  60  30
DLS  58  47  56  42 /  40  70  50  20

&&

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

$$

SHORT TERM...71
AVIATION...86