981
FXUS66 KPDT 261735
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1035 AM PDT Sat Apr 26 2025

.UPDATED AVIATION DISCUSSION...


.AVIATION...18Z TAFs...All sites will be VFR for this period. As the
trough moves across the PacNW, this can strengthen the surface
pressure gradients over the Cascade Gaps (KDLS/KRDM/KBDN/KYKM) thus
inducing breezy to windy conditions. KDLS will have winds gusting up
to 30kts throughout today whereas they decrease around this evening
for KRDM/KBDN and tomorrow morning at KYKM. Winds at KPDT/KALW/KPSC
will be 10 kts or less. Feaster/97


&&

.PREV DISCUSSION... /issued 241 AM PDT Sat Apr 26 2025/

.SHORT TERM...Today through Monday...Main feature over the
weekend continues to be a cutoff low situated well to our south
over central California. This system was originally thought to
bring at least some light precip to the eastern mountains and
central Oregon, but thus far, not much has materialized. A band of
showers is starting to inch into Grant County from the southeast,
as this cutoff low starts to introduce some wraparound moisture
into the region, but just from looking at CAMs, forecast models do
not seem to have initialized this system well. As a result, have
scaled back PoPs from what the NBM wants to depict, with the
caveat that a narrow area from Wallowa County to extreme
southeastern Deschutes County will remain under at least a slight
chance of PoPs. The synoptic set- up still favors an isolated
storm or two Saturday afternoon, but confidence is low (10-20%)
given, again, the poor grip models currently have on this system.

Gusty winds, however, are at a much higher level of confidence of
occurring. Already seeing some breezy gap winds through the Columbia
River Gorge and Kittitas Valley, which is expected to continue
through Sunday as this cutoff low leads to a decent cross-Cascade
pressure gradient. Guidance is suggesting winds just below advisory
level, but Sunday in particular could come close to >45 mph wind
gusts in the Kittitas Valley. Elsewhere, generally expect gusts in
the 15-25 mph range, with Sunday once again being the windiest day
of the period.

PoPs fall off by Sunday afternoon, with quiet weather expected
heading into Monday as dry NW flow prevails overhead. Expect
seasonal temperatures before another chance of light precip arrives
overnight Monday into Tuesday, as models introduce a weak shortwave
into the PacNW.

.LONG TERM...Tuesday through Saturday...Active weather will
bookend a period dry and quiet conditions across the forecast area
next week. Breezy conditions with mainly mountain and adjacent
foothill locations seeing showers develop with passing upper level
systems Tuesday and Friday through Saturday.

Ensemble members are in great agreement in an upper shortwave
trough sliding across the PacNW Tuesday with mainly mountain
showers (confidence 70-80%). Adjacent foothill locations,
including the foothills of the Blues will also see at least a
chance(30-50%) of showers as they develop into the Blue mountains
through Tuesday. Surface pressure gradients will remain tightened
across the area Tuesday, resulting in breezy conditions(30-40mph)
that will develop in the Cascade gap areas and weaken (20-30mph)
as they spill into portions of the Columbia Basin and adjacent
valleys (confidence 60-80%).

By Tuesday night, ensemble cluster guidance shows the upper
shortwave trough exiting to the east, allowing upper level ridging
to build back into the PacNW through Thursday. Conditions will
remain quite dry at the surface, while a warming trend will push
the afternoon temperatures well into the mid 70s to lower 80s
across the lower elevations (confidence 60-80%). Winds will also
remain light to locally breezy through Thursday.

Thursday night into Friday, there is great agreement amongst
ensemble cluster members that the upper level ridge over the area
will be pushed east into the Rockies by an upper trough
approaching from the northeast Pacific. Agreement remains good
that the upper trough will traverse east into Western CONUS Friday
into Saturday, providing rain shower chances across the
PacNW(confidence 40-60%) and a cooling trend into next
weekend(confidence 45-60%). That said, there is disagreement
amongst each of the four ensemble cluster solutions in the
strength/timing of the upper trough passage across the area,
resulting in low confidence (20-30%) in forecast details
(precipitation amounts, temperatures, etc.) at this time.
Lawhorn/82


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  74  45  69  43 /   0   0   0   0
ALW  73  48  69  46 /   0   0   0   0
PSC  80  46  76  44 /   0   0   0   0
YKM  80  46  75  45 /   0   0   0   0
HRI  79  46  73  45 /   0   0   0   0
ELN  75  46  68  45 /   0   0   0   0
RDM  69  35  64  32 /  10   0   0   0
LGD  69  44  65  39 /  30  10   0   0
GCD  66  42  65  37 /  40  10   0   0
DLS  72  44  65  45 /   0   0   0   0

&&

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

$$

SHORT TERM...74
LONG TERM....82
AVIATION...97