204
FXUS66 KPDT 030538
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
938 PM PST Mon Mar 2 2026

.Updated for Aviation...



.KEY MESSAGES...
- Widespread precipitation chances return Tuesday into
  Wednesday, with persistent mountain precip chances continuing
  into the weekend.

- Winter Weather Advisory in effect above 4500ft for the OR
  Cascade Crest Wednesday.

- Potential for breezy to gusty winds (gusts 35-50 mph)
  developing Wednesday with cold front passage.



.DISCUSSION...
Through Tuesday Afternoon: A transient upper ridge is currently
moving onshore the PacNW today, resulting in a return of area-
wide dry conditions. Some warm air advection with the upper
ridge will bring temperatures closer to the lower to mid 60s
across much of the Columbia Basin in the afternoons Today and
tomorrow. Otherwise, sky cover will begin to increase late
tonight into tomorrow morning from the west, as the next upper
level trough approaches the PacNW. This may limit viewing
potential for the lunar eclipse early tomorrow morning, with
cloud cover expected to cover the western third of the forecast
area by the time of the eclipse totality (3am-4am PST). The only
saving grace with the incoming cloud cover is that it may start
off as a thinner or scattered cirrus deck (confidence 50-70%).

By tomorrow afternoon, a weak frontal boundary will reach the
Cascade crest, with light rain/snow showers developing into the
evening. As precipitation starts, snow levels will be above
5kft to 5.5kft, resulting in mostly rain at pass level, with
snow or a rain/snow mix above these elevations.

Tuesday night through Thursday morning: There is great
agreement amongst ensemble and deterministic guidance that an
upper trough passage Tuesday night through Wednesday night will
bring widespread precipitation chances to the PacNW. Snow
levels will start off just above 5kft with the approach of the
trough, but drop to 4kft to 5kft as the trough moves inland
Tuesday night into Wednesday morning. The heaviest of the
precipitation will align with snow levels just falling to or
below the surface along the Cascade crest Tuesday night,
resulting in wet snow accumulations of 2 to 5 inches by
Wednesday afternoon(confidence 70-85%). Through the rest of
Wednesday, snow levels will continue to lower to 3kft to 4kft,
resulting in more widespread snow in the mountains. Scattered snow
showers will develop as the trough axis moves overhead and a
cold front boundary to the east. As the trough axis pushes
further east, snow rates will become very light across the
forecast area. Through Thursday morning, Santiam Pass will see
a 65-85% chance for snow accumulations greater than 6 inches. As
a result, a winter weather advisory has been issued for the
Oregon Cascade East Slopes above 4,500ft for Wednesday. At
Snoqualmie pass, snow levels will generally be above pass level
through Wednesday, resulting in only a 35-50% chance of an inch
of snow accumulating through Thursday morning. In the interior
northern Blues and in White Pass, there is a 55-85% chance of 2
inches of snow through Thursday morning; there is a 65-85%
chance of 4 inches of snow through Thursday morning along the
Elkhorn crest.

Below the mountains, most lower elevation locations will see a
45-80% chance of rain accumulations greater than 0.05 inches
develop as the trough axis and an attendant cold front sweep
through the area. Heaviest rain amounts will be along the
northern Blue mountain foothills, where there is a 40-80% chance
of accumulations greater than 0.2 inches through Thursday
morning. Otherwise, ensemble guidance is depicting breezy winds
(gusts 35-50mph) developing with the aforementioned cold front
passage Wednesday (confidence 65-75%), with strongest winds
along the Cascade peaks/ridges and ridges in the Columbia Basin.

Thursday through the weekend: There is good agreement in the
latest ensemble cluster guidance that northwest flow aloft will
develop initially, leaving light rain/snow chances along the
Cascade crest and Northern Blue mountains Thursday. Weak
northerly flow will then develop over the PacNW Thursday night
into Friday as a ridge amplifies offshore and a trough digs
equatorward in the inland western CONUS. Weak mountain showers
along the Cascade crest will continue under this flow regime
throughout Thursday, with dry conditions elsewhere. Ensembles
remain in good agreement Friday through the weekend that
northerly flow will shift to the northwest as the ridge flattens
offshore, resulting in light showers across the Cascades and
Northern Blues (confidence 55-75%). Snow levels will also rise
Friday night into Saturday, limiting snow to mountain peaks,
with rain or rain/snow mix mainly below 6kft (confidence
45-65%). Otherwise, locally breezy west winds (25-40mph gusts)
will redevelop in the daylight hours each day through Sunday
(confidence 50-65%). Lawhorn/82

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
VFR conditions are expected through Tuesday. Winds will
generally be 10 kts or less.

&&

.Preliminary Point Temps/PoPs...
PDT  35  60  43  53 /   0   0  40  90
ALW  40  61  45  53 /   0   0  60  90
PSC  35  63  44  59 /   0   0  20  60
YKM  34  58  40  56 /   0  10  30  50
HRI  35  62  43  57 /   0   0  30  80
ELN  33  52  37  50 /   0  10  40  60
RDM  30  58  37  47 /   0   0  10  90
LGD  33  59  41  49 /   0   0  50 100
GCD  32  58  39  47 /  10   0  20 100
DLS  40  57  45  55 /   0  20  70  90

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...None.
OR...Winter Weather Advisory from 4 AM to 10 PM PST Wednesday for
     ORZ509.

&&

$$

UPDATE...88
DISCUSSION...82
AVIATION...77