939
FXUS66 KPDT 031712
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1012 AM PDT Fri Oct 3 2025

Updated Aviation Discussion

.AVIATION...18z TAFs...VFR conditions expected at most sites,
however area haze and smoke from regional wildfires may make for
sub-VFR conditions at YKM and PSC during the day today. Risk is
higher at YKM, where the smoke is less elevated. Elsewhere, expect
generally W/NW winds at 8-12 kts, except for DLS, where winds
could gust as high as 25 kts this afternoon. Skies will clear
during the day today, before a sct-bkn mid-level ceiling moves in
this evening. Evans/74

&&

PREV DISCUSSION... /issued 126 PM PDT Thu Oct 2 2025/

DISCUSSION...

Key Messages:

1. Periods of showers and isolated thunderstorms today.

2. Cooler conditions through the weekend.

3. Cold morning temperatures Sunday through Tuesday.

Current radar and visible satellite imagery showing spotty, light
returns along the Blue Mountains and the east slopes of the
Cascades under mostly cloudy skies. This is in response to an
upper level trough and associated cold front stalling along the
coast. The deepening offshore trough and erosion of the ridge to
our east will promote the potential for isolated afternoon
thunderstorms across areas of Central Oregon and the Blue
Mountains/Foothills. The HREF advertises 100-200 J/kg of surface
CAPE, low level shear of 50-55kts, and lapse rates of around 6/km.
These parameters do suggest the potential for isolated, discrete
storm cells to form, but should stay brief and sub-severe (<10% of
severe storms).

Rain chances will will peak between 2 PM and 7 PM today before
tapering off over the Blue Mountains and foothills until closer to
11 PM. Minimal rain amounts are expected, with highest
accumulations across the Southern Blue Mountains, John Day
Highlands, and the east slopes of the Oregon Cascades with amounts
between 0.10-0.20" likely. There could be areas of slight higher
amounts nearing 0.20-0.30" at higher elevations and near
developing thunderstorm cells, but chances are relatively low
(30-40%) via the NBM. The Blue Mountain foothills, North-Central
Oregon, John Day Basin, and Wallowa/Union counties are expected to
receive 0.02-0.10", with less than 0.02" expected across the Lower
Columbia Basin and conditions staying dry over the Yakima/Kittitas
Valleys.

The upper level trough offshore digs south tonight and moves
onshore over Northern California Friday morning before progressing
into the Las Vegas area by Friday evening. A brief transient ridge
will follow in the dropping system`s wake on Friday, bringing with
it drier conditions through the majority of the day. An second
upper level trough will drop through British Columbia and into
northeastern Washington Saturday, bringing a return to light rain
chances (20-30%) across the Cascades and Blue Mountains during the
morning and afternoon. Minimal rain amounts are expected of 0.03"
or less across mountainous terrain of the Blue and Cascade
Mountains, with the NBM suggesting a 40-50% of 0.02" or more rain
over the aforementioned areas Saturday.

Northwest flow will initiate Friday and extend into early next
week, keeping temperatures below normal and dropping low
temperatures into the upper 20s across lower elevations of Central
Oregon as upper level flow becomes more northerly. Ensembles are
currently looking more favorable for low temperatures to bump up
slightly both Sunday and Monday mornings with 52% of members on
Sunday and 80% of members on Monday related to more of a marine
influence slowing overnight cooling. At this time, there is a
30-50% chance of freezing temperatures for Redmond, Bend, and La
Grande Sunday morning, a 50-80% chance on Monday morning, and a
30-60% chance on Tuesday morning.

Ensembles struggle with the overall pattern Tuesday onward as
members suggest a ridge offshore and a dropping system midweek. At
this time, the leading scenario (50-60%) is another dropping
system offshore Thursday, bringing a return to widespread light
rain chances to the area. 75

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  68  46  67  42 /  10  10  20  10
ALW  68  49  67  45 /  10  10  20  20
PSC  72  47  71  42 /   0  10   0   0
YKM  72  47  70  42 /   0  10  10   0
HRI  71  48  70  43 /  10  10  10  10
ELN  69  44  66  37 /   0  20  10  10
RDM  64  36  62  33 /  10  10  20  10
LGD  64  40  61  37 /  30   0  30  20
GCD  64  38  60  37 /  20   0  20  10
DLS  72  52  70  48 /  10  20  40  10

&&

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

$$

SHORT TERM...75
LONG TERM....75
AVIATION...74