505
FXUS66 KPDT 040506
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
906 PM PST Mon Nov 3 2025

Updated Aviation Discussion

.AVIATION...06z TAFs...Rain showers will gradually taper off
overnight, with most sites seeing VFR conditions this evening,
however a combination of recent moisture and light, upslope winds
may make for low cigs less than 3 kft at some sites early morning
Tuesday. Weather models seem to suggest this as well, however
confidence is only moderate (50%) due to how high cigs currently are
this evening (3-7 kft). Should see some improvement regardless by
late morning Tuesday, before another round of rain showers arrives
by the early afternoon in BDN/RDM, spreading northeastward through
the evening. Cigs under rain are expected to be above MVFR criteria,
however. 74

&&

PREV DISCUSSION... /issued 150 PM PST Mon Nov 3 2025/

DISCUSSION...Today through Tuesday morning: Rain and Cascade snow
showers have already developed ahead of an approaching surface
low and broad shortwave trough today, with main activity being
mostly seen across the WA half of the forecast area. This trend
will continue through tonight as both low features swing into the
PacNW, however, the best precipitation chances will aligned
across WA as the right 250-300mb jet entrance and left 700mb jet
exit align over this area, aiding in precipitation enhancement.
While most mountain locations will see a rain/snow mix above 6kft,
cold pooling on the lee side of the WA Cascades will result in
snow levels initially around 3.5kft to 4kft, with snow levels
rising gradually above 4kft tonight, with snow levels rising above
5kft to 5.5kft across White Pass and areas to the south tonight.
This will result in initially moderate to localized heavy snow
through this afternoon, but passes through the central WA Cascades
will see a transition to a rain/snow mix then mostly rain
overnight. Through tomorrow morning, there is only a 40-45%
chance of 5 inches of snow at White Pass, while that chance is
10% or less for Snoqualmie and Blewett passes. Otherwise, there is
a 50-80% chance for 0.5 inches of QPF for the northern Blues and
along the OR Cascade crest, with a 70-90% chance across the WA
Cascades; there is a 50-80% chance for 0.15 inches of rain across
the Columbia Basin and adjacent foothills/valleys, while central
OR and the eastern mountains are looking at a 15-40% chance. A
brief dry period will develop Tuesday morning as transient
ridging slides into the PacNW behind the surface low/shortwave
trough exit.

Tuesday afternoon through Friday night: A fairly active stretch
of weather will develop the second half of Tuesday through Friday
night as a series of troughs and surface fronts swing across the
PacNW (confidence 70-80%). Snow levels will remain above pass
level through Thursday, thanks to plenty of warm air advection
with the initial trough and warm front passage Tuesday into
Wednesday. But by late Thursday night through Friday, snow levels
will descend back to 4.5kft to 5.5kft, albeit after the bulk of
precipitation occurs with a cold front and shortwave trough
passage. In the lower elevations, there is a 40-80% chance of 0.3
inches or greater of rain accumulations through a 72 hour period
ending Friday morning; there is a 60-90% chance of 0.5 inches of
rain in the eastern mountains and Blues; and a 80-100% chance of
at least 1.5 inches of QPF along the Cascade crest and east
slopes. Meanwhile, the 24-hour chance ending Friday afternoon of
snow accumulations greater than 2 inches is 30-35% for White Pass,
while the remaining passes across the forecast area are less than
10%.

The incoming systems will also result in a period of breezy to
locally windy conditions developing across the forecast area
through Friday afternoon. The strongest of these winds will occur
during the onset of the active weather period Tuesday night
through Wednesday afternoon. Ensemble members and deterministic
guidance is in great agreement of a strong 700mb jet (55-65kts)
developing across central OR and the eastern mountains Tuesday
night into Wednesday with a cold front passage Wednesday morning.
Much like previous events in the last week or two, winds will mix
down to the surface with the cold front passage, resulting in
moderate confidence (50-70%) that strong wind gusts (40-55mph)
will develop across portions of central OR, the southern Blue
mountain foothills, and along ridgetops across the eastern
mountains. Otherwise, breezy winds (gusts 25-40mph) will continue
to impact the lower elevation areas late Wednesday through Friday.

Saturday through Sunday: Great agreement amongst ensemble cluster
members (GFS and ECMWF) in a ridge of high pressure building
across the PacNW over the weekend with a weak warm front riding up
the backside of the ridge. This will result in mostly light winds
with dry conditions, however there is moderate confidence (40-60%)
in light precipitation developing across the Cascade crest with
the warm front passage. By late Sunday, ensemble guidance depicts
an upper trough developing offshore the PacNW by Sunday morning,
then pushing the trough inland Sunday night with increasing rain
and high mountain snow chances across the forecast area (30-55%
confidence). Lawhorn/82

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  37  56  42  62 /  90  20  70  80
ALW  40  54  45  60 / 100  40  70  90
PSC  36  52  40  58 /  90  20  70  70
YKM  36  49  40  54 / 100  40 100  90
HRI  38  53  42  60 /  90  20  70  70
ELN  32  46  36  51 / 100  40 100  90
RDM  34  57  42  60 /  60  60  90  80
LGD  39  57  47  58 /  90  30  80  90
GCD  41  59  47  59 /  80  50  80  90
DLS  41  54  45  58 / 100  60 100 100

&&

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

$$

SHORT TERM...82
LONG TERM....82
AVIATION...74