019
FXUS66 KPDT 262153
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
253 PM PDT Sat Apr 26 2025

.SHORT TERM...This afternoon through Monday night...Convection is
ongoing along the crest of the northern Blue Mountains, with Day
Cloud Phase RGB satellite imagery showing glaciating cloud tops.
That said, cells have been relatively shallow, barely pulsing up
to 20 kft and lightning has been scant over the entire region.
Lack of shear should keep any thunderstorms that do develop of
the air mass variety, and storm motions of 5-10 kts suggest cells
will be slow-moving. Stronger cells this afternoon have produced
some locally heavy rainfall and small hail. Elsewhere, the cumulus
field along portions of the Simcoe Highlands, Lower East Slopes
of the Eastern Washington Cascades Crest, and much of the Blue
Mountains region has seen less vertical development with more
isolated showers.

The primary focus of the forecast this afternoon revolved around
potential for meeting Wind Advisory criteria through the Cascade
gaps today and Sunday. While DLS/ELN have flirted with advisory
criteria this afternoon, confidence in either location sustaining
advisory criteria for greater than an hour is too low (<40%) to
issue any highlights. For what it`s worth, current surface
pressure differences are 5-7 mb across the Cascades from PDX-DLS
and SEA-ELN.

Looking ahead, high-resolution guidance is advertising a more
robust marine layer on the west side of the Cascades tomorrow.
Moreover, west-side temperatures will be 5-15 degrees cooler than
over here on the east side, helping to aid afternoon surface
pressure gradients much the same as this afternoon. Forecast
surface pressure differences between PDX-DLS and SEA-ELN are in
the 6-9 mb range, slightly higher than today. All together, the
setup for widespread windy westerlies through the Cascade gaps
is quite good. That said, have held off on issuing wind
highlights in favor of letting the evening/overnight shifts have
another look; confidence is medium-high (60-75%) in needing Wind
Advisories for the Kittitas Valley and Eastern Columbia River
Gorge, with lower confidence (40-60%) for the Simcoe Highlands,
North-Central Oregon, and portions of the Lower Columbia Basin of
Oregon and the Foothills of the Southern Blue Mountains.

Otherwise, mostly dry conditions will persist through Monday,
aside from isolated showers tomorrow afternoon over the higher
terrain of Wallowa County. Widespread breezy conditions through
the Cascade gaps are forecast again Monday.

NWP guidance advertises the arrival of the next shortwave trough
from the Pacific late Monday night, with light precipitation
arriving towards Tuesday morning. Plunkett/86

&&

.LONG TERM...Tuesday through Saturday...Showers will develop
Tuesday across majority of the forecast area with the passing
shortwave trough. As the trough gradually moves out, showers may
continue lingering at the Blues and WA/OR Cascades Tuesday
afternoon into the evening but dries out for the lowlands. And
with the tightened surface pressure gradients, winds will be
breezy (15-25 mph) in the morning and then windy (25-35 mph)
around afternoon through the evening at the Cascades gaps before
decreasing. Wednesday and Thursday will be warm and dry with the
upper ridge building over the PacNW. No precip will be expected
until Thursday night when light showers develop over the Cascades
first.

From Thursday night onwards, a shortwave trough with an
associated cold front sweeps across the PacNW. This could also
increase chances of active showers and gusty winds. Lower Basin,
Simcoe highlands, OR Cascades and Yakima Valley may have QPF
amounts of 0.10" or less, though with the Blues and WA Cascades up
to 0.35" into Friday night. Saturday is when precip activity
start to weaken, but lingers over the Blues and OR Cascades. Windy
conditions will remain up to 35 mph or more for the Cascade Gaps
Friday and Saturday during afternoon and evening hours.

High temperatures will be mainly in the 70s through Wednesday.
With the ridge building over, Thursday will be our warmest day
with the Columbia Basin and central OR reaching to the low 80s.
Friday and Saturday starts to gradually cool to the 70s across
most of the forecast area once the trough moves onshore.
Feaster/97

&&

.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

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  45  69  43  71 /   0   0   0   0
ALW  48  70  46  70 /   0   0   0   0
PSC  46  77  44  75 /   0   0   0   0
YKM  46  75  45  76 /   0   0   0   0
HRI  46  73  45  74 /   0   0   0   0
ELN  45  68  45  69 /   0   0   0   0
RDM  34  64  32  70 /   0   0   0   0
LGD  43  65  39  67 /  20   0   0   0
GCD  41  66  37  69 /  20  10   0   0
DLS  43  64  45  68 /   0   0   0   0

&&

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

$$

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