328
FXUS66 KPDT 301731
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1031 AM PDT Fri Oct 30 2026

.Updated Aviation Discussion.


.KEY MESSAGES...
- Near- to below-normal temperatures into next week.

- Periodic showers today, mainly along the Cascade crest.
  Medium-high (30-70%) chance of precipitation for
  central/eastern Oregon and southeast Washington over the
  weekend.

- Low chance (30% or less, except for freeze-prone areas) of a
  season-ending freeze for the eastern Columbia River Gorge
  Saturday and Monday.

&&

.DISCUSSION...
Not too much of a change in satellite imagery since yesterday`s
discussion. Water vapor imagery shows a large, quasi-stationary
low-pressure system located just offshore of the Pacific
Northwest. Middle and high cloud cover has increased since
yesterday, and this appears to have helped put a damper on
notable fog formation early this morning. Radar reveals little
in the way of returns over the forecast area.

Ensemble NWP guidance is in excellent agreement that a shortwave
currently visible just off the southwest Oregon coast will
round the aforementioned upper-level low later this morning and
induce low chances (30% or lower) of showers for the Oregon
Cascade crest and medium chances (30-70%) of showers for the
Washington Cascades. Farther east, dry conditions are forecast.

Over the weekend, the low is expected (95% confidence) to
transition to an open-wave trough and move inland. While
chances of precipitation have trended downward slightly, they
are still medium-high (30-70%) across the majority of
central/eastern Oregon and southeast Washington Saturday
afternoon through Sunday morning. The best chance of significant
precipitation will be over Wallowa County where the NBM places
a 30-60% chance of 0.25" and 10-30% chance of 0.50" of QPF
through Sunday.

Ensemble solutions are coming into a better concensus with
regard to when the trough will exit to the east and upper-
level ridging will build in from the Pacific; specifically,
ensemble means suggest the trough will slide east late Sunday
afternoon into Sunday night, and an amplified upper-level ridge
will be overhead by Monday morning. Given clearing skies and
dry conditions, this presents the best chance, albeit low at
30% or less, of a season-ending freeze for the eastern Columbia
River Gorge. Freeze-prone portions of the Gorge do have
somewhat higher chances of freezing, but at this time confidence
remains too low to issue any watches.

Uncertainty in the 500-hPa pattern then grows Tuesday through
the remainder of the week. Aside from a very low chance (5-15%)
of precipitation on Tuesday, mostly dry conditions are forecast
to continue until Thursday when ensemble guidance hints at the
return of some more active weather. Even then, chances of
precipitation remain low (40% or less, highest for the
Cascades).

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Varied conditions currently across sites this morning, with VFR
at KPSC/KDLS/KBDN/KYKM, MVFR at KPDT, and IFR at KRDM/KALW due
to reduced ceilings of 700-800 feet. These ceilings are expected
to lift as categories improve to VFR shortly at both terminals.
Winds will stay light and below 10kts for all sites through the
period. Fog is expected to return for KPDT overnight tonight,
dropping visibilities to around 1/2SM. 75

&&

.Preliminary Point Temps/PoPs...
PDT  49  33  50  34 /   0   0   0  40
ALW  50  36  51  37 /   0   0  10  50
PSC  54  31  54  34 /   0   0   0  20
YKM  53  31  54  33 /  10   0   0  10
HRI  52  31  51  33 /   0   0   0  30
ELN  49  23  50  27 /  10   0   0  10
RDM  50  24  48  26 /   0   0  10  40
LGD  57  32  57  36 /   0   0  30  60
GCD  57  34  57  36 /   0   0  10  40
DLS  55  33  55  36 /  10   0   0  30

&&

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

&&

$$

DISCUSSION...86
AVIATION...75