822
FXUS66 KPDT 281736
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1036 AM PDT Wed Oct 28 2026

.Updated Aviation Discussion.


.KEY MESSAGES...
- Moderate snow accumulations across the WA Cascades through
  this morning, with intermittent light mountain snow/rain
  through the weekend

- Breezy south to southwest winds today

- Below normal temperatures through the week

&&

.DISCUSSION...
Water vapor satellite imagery tonight shows an
upper closed low over Vancouver Island and southwest BC, while
the PacNW sits under a broad upper trough. Radar and nighttime
satellite imagery show rain/snow showers rounding the southern
flank of the upper closed low into the WA Cascades. Elsewhere,
clear to partly cloudy conditions are present over the lower
elevations, with low stratus over portions of the eastern
mountains.

Today through Friday: The upper closed low just north of the
Olympic Peninsula will continue to guide light to moderate
rain/snow showers into the WA Cascades the remainder of today,
with light rain/snow showers expanding across the OR Cascades
and northern Blues later this morning into the evening hours.
A cooler airmass associated with this low will continue to
filter into the region this morning, with snow levels lowering
to around 3.5-4.5kft by sunrise. The increased shower activity
will bring snow accumulations of 3-7 inches above 4kft along
the WA Cascades, with accumulations generally 1-3 inches above
5kft in the OR Cascades, Elkhorn Crest, Eagle Caps, and interior
northern Blues(confidence 75-85%). A Winter Weather Advisory is
currently in effect for the Upper East Slopes of the WA
Cascades through this afternoon.

Shower activity is expected to weaken and become intermittent
through Friday as the upper low remains parked offshore. Any
additional snow accumulations along the Cascade crest will be
between 1-2 inches through Friday night (confidence 65-75%),
with very low chances (5-15%) of a dusting (~0.1 inches) across
the remaining mountain zones.

Otherwise, a cooling trend associated with the upper closed low
will result in afternoon temperatures lowering into the 50s
today, then lower further into the mid 40s to low 50s
tomorrow and Friday (confidence 75-90%). Chances will increase
through the week for near to below freezing low temperatures
in the lower elevations, with best chances (75-95%) arriving
Saturday morning. Freeze warnings may be needed by Saturday
morning for areas that have not received an area-wide season
ending freeze. Breezy south to southwest winds (15-25mph with
gusts to around 35mph) will continue to impact portions of
central OR to the Columbia Basin today, with light winds
returning later this evening.

Saturday through Tuesday: Ensemble guidance is in agreement of
the upper closed low sliding inland Friday night into Saturday,
with continued chances of light rain/snow in the mountains
through at least Saturday afternoon(confidence 60-75%).
Saturday night into Sunday, the upper trough will push into the
northern Rockies, allowing an upper level ridge to slide over
the region Sunday through Monday with dry conditions (confidence
55-65%). After Monday afternoon, ensemble guidance is split
into three scenarios. The first scenario is the upper level
ridge gradually pushing east, but the PacNW remains under
dry/calm conditions with a slight warming trend(~50% of Ensemble
cluster members). The second scenario is for a shortwave trough
to flatten the upper ridge as it moves across southern BC and
northern WA, with a return of light mountain rain/snow across
the Cascades and northern Blues Monday night into Tuesday (~30%
of members). The last scenario is for an upper trough in the
eastern Pacific to slide into the northern CA and southern OR,
resulting in light shower activity along the Cascades and
eastern mountains. Forecast confidence for early next week is
low (10-15%) given the spread in ensemble forecast scenarios.
Lawhorn/82

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
VFR conditions currently across all sites, which will stay the
course through the period. Light, brief showers will still be
possible for KDLS/KPDT/KYKM/KALW through this afternoon, with
only KDLS possibly dropping to 6 SM visibilities due to rain
showers. Breezy afternoon winds at KPSC/KPDT/KRDM/KBDN as gusts
of 20-25kts are likely. 75

&&

.Preliminary Point Temps/PoPs...
PDT  54  33  52  32 /  30  10   0   0
ALW  53  36  54  35 /  60  20   0   0
PSC  59  30  54  31 /  10   0   0   0
YKM  56  27  52  31 /  30   0   0  30
HRI  57  31  52  31 /  10   0   0   0
ELN  48  22  46  23 /  80  10   0  20
RDM  49  21  51  21 /  10  10   0   0
LGD  52  29  56  30 /  30  30   0   0
GCD  51  28  57  31 /  10  10   0   0
DLS  56  33  54  34 /  90  30   0  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory until 5 PM PDT this afternoon for
     WAZ522.
OR...None.

&&

$$

DISCUSSION...82
AVIATION...75