417
FXUS66 KPDT 201136
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
436 AM PDT Sun Sep 20 2026

.KEY MESSAGES...

- Warming trend through Monday with highs in the low to mid 80s
  in the lower elevations. Cooler temperatures towards the mid
  to late week.

- Next possible weather system pushing towards the end of the
  week, with chances of mountain showers going up.

- Light diurnal winds prevail, with the exception of breezy
  winds in the Cascade gaps Tuesday and Wednesday.

&&

.DISCUSSION...
Zonal/slight ridging continues to prevail the area, continuing
the dry and clear pattern and will continue to do so through the
next couple of days. The warming trend continues through Monday
when highs peak in the low to mid 80s across the lower
elevation areas. Winds will be mostly light and variable with
diurnal winds with the exception of breezy winds developing in
the Cascade gaps Tuesday and Wednesday.

Our next weather maker will occur in the late part of this week
as a trough/shortwave off British Colombia pushes into the PacNW
(30-50% chance). Models struggle how to handle the system as we
get close to the weekend, as there`s not a concise conclusion
with clusters and guidance on timing and strength of the trough.
Confidence is rather low (10-30%) that the lower elevation
areas will see precipitation, while higher confidence is placed
on the mountain regions (50-70% chance) by Friday and Saturday.
For more in-depth with the clusters, 27% of members want to
bring a wet pattern in the lower elevations by Friday afternoon
with a stronger trough advertised, while that number jumps to
around 70% for the areas in the mountains. Still time to monitor
this system, but not expecting any significant impacts with this
system at the time with plenty of time to monitor for any
evolving details over the next few days.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
VFR conditions prevail through the period with light and
variable winds. Dry conditions prevail with SKC to SCT
conditions through the period. No CIG or VIS issues expected.

&&

.Preliminary Point Temps/PoPs...
PDT  83  50  84  53 /   0   0   0   0
ALW  85  56  85  59 /   0   0   0   0
PSC  86  52  87  53 /   0   0   0   0
YKM  84  54  85  54 /   0   0   0   0
HRI  85  53  86  54 /   0   0   0   0
ELN  79  52  80  51 /   0   0   0   0
RDM  84  45  84  45 /   0   0   0   0
LGD  83  51  84  52 /   0   0   0   0
GCD  84  50  85  51 /   0   0   0   0
DLS  88  59  86  56 /   0   0   0   0

&&

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

&&

$$

DISCUSSION...95
AVIATION...95