932
FXUS66 KPDT 282303
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
403 PM PDT Mon Sep 28 2026

.KEY MESSAGES...
- Light to moderate rain showers (70-90% chance) along the
  Cascade Mountains on the Washington side, with lighter amounts
  along the Northern Blue Mountains.

- Breezy winds develop across the Cascade gaps and other parts
  of the Basin.

- Temperatures will be near to slightly above normal throughout
  the week.

&&

.DISCUSSION...
Very little activity with satellite and radar currently as zonal
flow currently dominants aloft. Overnight freezing was present
in parts of Central Oregon and the Wallowa`s, we may see a
second round of some freezing although confidence is lower this
time around (10-20% chance) as winds are stronger tonight
compared to last night. Given that, I`m not expecting freezing
temperatures, if any, will last enough to warrant freeze
warnings tonight.

Our next weather maker and cold frontal system is around the
corner, but will mostly impact the mountain regions and parts of
the Foothills of the Blues to a lesser extent. A
trough/shortwave located in the Pacific and British Colombia
will move along the area, bringing light to moderate rain
showers in the Washington Cascades (70-90% chance), Northern
Blue Mountains (20-40% chance), and parts of the Foothills of
the Blues (up to 20% chance). Guidance makes it pretty clear
that parts of the Cascade region near Snoqualmie (and the Three
Queens fire) will see wetting rains develop over the 24-48
hours. It`s keyed in that region will see at least a tenth of an
inch of rain (>90% chance), while seeing a quarter of an inch is
also very likely (75-85% chance). Current NBM guidance
advertises nearly an inch close to Snoqualmie pass while it
quickly drops off the further away from the peaks you are. The
secondary maximum of QPF is located in the Northern Blue
mountains with only up to a tenth of an inch advertised (50-70%
chance). While Snoqualmie could get up to an inch, it`s
unlikely we`ll see any widespread flooding (even on burn scars)
happening, although the chance for localized flooding in flood
prone areas is not out of the question. The front will also
increase PG`s across the area, developing breezy to locally
windy conditions across the area (especially near the Gaps and
parts of the Basin). Wind gusts in the strongest areas could
reach 30-40 mph (50-70% chance).

Clusters struggle a bit trying to handle the strength of zonal
flow ahead of a ridge pushing onshore. About 29% of clusters
want to keep the zonal flow above the area, bringing additional
light to moderate mountain showers. Something to monitor, but
no big impacts are expected from this set-up with any QPF`s
falling should be light to moderate (80-90% chance). Guidance
paints the end of this week through next week as a ridge
amplifying over the PacNW, bringing dry and warm conditions.
Something to keep an eye out fire weather wise, but any impacts
on RH`s and/or winds is a bit too far out to make any
conclusions.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
VFR conditions will persist through the forecast period. Winds
will be elevated at or near 10 kts at PDT/BDN and gusting to
near 20 at DLS through 02-03Z. Winds will become breezy at
PDT/ALW/PSC in the morning after 17-19Z.

&&

.Preliminary Point Temps/PoPs...
PDT  45  75  49  72 /   0   0   0   0
ALW  52  75  54  73 /   0   0  10   0
PSC  47  78  50  75 /   0   0   0   0
YKM  48  74  49  71 /   0  10   0   0
HRI  49  77  51  75 /   0   0   0   0
ELN  45  66  46  66 /   0  20  20   0
RDM  37  75  39  74 /   0   0   0   0
LGD  41  75  46  71 /   0   0  10  10
GCD  40  75  43  74 /   0   0   0   0
DLS  50  73  54  76 /   0   0  10   0

&&

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

&&

$$

DISCUSSION...95
AVIATION...90