Area Forecast Discussion
Issued by NWS Pendleton, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KPDT 261012
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
312 AM PDT Tue Mar 26 2024

.SHORT TERM...Today through Thursday night...Satellite reveals a
northwesterly flow over the forecast area with radar picking up
showers across much of our area mountains including the Cascade
crest and the Blue Mountains. Area web cameras show accumulating
snow at pass levels of roughly 4000 feet and above, though more
intense snow showers are likely to induce rate-driven, localized
lowering of snow levels below 4000 feet this morning. Those
traveling over mountain passes should be prepared for sudden
changes in visibility and road conditions in the aforementioned
snow showers.

This afternoon, though mid- and upper-level moisture is advertised
to diminish compared to this morning, the weak passing shortwave
aloft in tandem with modest instability (00Z HREF-advertised MUCAPE
of <500 J/kg) may serve as a catalyst for isolated to scattered
convective showers with the best chances of measurable
precipitation in the Blue Mountains (40-75% chance). Relatively
low chances of showers are forecast for the lower elevations (<25%
chance). While unlikely based on 00Z HREF soundings (15% chance
or less), cannot rule out an isolated thunderstorm across Wallowa
County this afternoon.

In terms of other tangible weather today, breezy westerly winds
are forecast this morning and afternoon through the Cascade gaps
and into portions of the Columbia Basin. Confidence is low-
moderate (20-50% chance) in sustained winds reaching 30 mph along
the foothills of the Blue Mountains and southern portion of the
Oregon Columbia Basin.

Looking ahead, ensemble guidance is in excellent agreement that a
brief upper-level ridge will build over the PacNW with mostly dry
conditions Tuesday night into Wednesday morning. Guidance is then
in excellent agreement regarding the timing of the next Pacific
frontal system for later Wednesday morning through Wednesday
afternoon. A warm front is expected to approach the forecast area in
the morning with breezy to windy southerly winds forecast
Wednesday across the Blue Mountains and adjacent foothills and
through the Grande Ronde Valley. Cold frontal passage is anticipated
Wednesday afternoon and evening.

The parent closed upper-level low is then expected to spin
offshore through the remainder of the period with showers forecast
until Thursday night. Plunkett/86

&&

.LONG TERM...Friday through Tuesday...Friday will see an upper
level closed low just off the PacNW coast placing the forecast
area under a southwest flow. Combine this with some marginal
instability and the forecast area will see some shower activity
build up through the day and then decrease overnight. The low will
drop south and be off the central California coast on Saturday
leaving the forecast area between the closed low and a trough
passing to the north through central Canada. This will provide a
generally more stable atmosphere over most of the forecast area
with just some lingering showers over the mountains. The low off
the coast of California will begin to move inland into the Great
Basin and Desert Southwest on Sunday allowing a ridge of high
pressure to begin pushing into the Pacific Northwest for the
eastern Pacific. Could still see a few lingering showers over the
far eastern mountains but overall the arrival of the ridge will
usher in a dry period Sunday through the first of the week. This
will see a warming trend and generally light winds Monday and
Tuesday. The ridge will begin to breakdown and be pushed to the
east by an upper level trough system in the Gulf of Alaska late
Tuesday. Depending on the timing in the models this could begin to
push a cold front into the region late Tuesday afternoon or
night.

&&

.AVIATION...06Z TAFS...All sites will be VFR for the remaining TAF
period. Moderate winds will continue during Tuesday morning with
gusts between 19-26mph but may likely decrease late morning
except for KYKM, KALW, and KPSC (60% confidence). KALW has a 40%
probability for rain showers early morning starting from 10Z to
16Z. Other than that, winds will be below 10kts. Feaster/97

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  54  33  57  37 /  20   0  80  80
ALW  57  37  58  39 /  30   0  80  90
PSC  61  39  58  41 /  10   0  80  50
YKM  60  33  52  33 /   0  10  90  10
HRI  60  36  60  37 /  10   0  80  60
ELN  55  32  48  31 /   0  10  90  20
RDM  50  33  54  31 /   0  10  70  40
LGD  49  29  51  34 /  50   0  70 100
GCD  48  29  52  33 /  40  10  90  90
DLS  57  41  54  39 /  10  20  90  40

&&

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

$$

SHORT TERM...86
LONG TERM....91
AVIATION...97


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.