473
FXUS66 KPDT 201708
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1008 AM PDT Fri Sep 20 2024

.UPDATED AVIATION...18Z TAFs...VFR conditions will prevail through
the forecast period. CIGs will be mostly clear skies with some
high clouds moving overhead later in the period. Winds will
continue to remain breezy at DLS through 03Z, PDT through 23Z and
RDM/BDN through 20Z. Bennese/90


&&

.PREV DISCUSSION... /issued 236 AM PDT Fri Sep 20 2024/

SHORT TERM...Today through Sunday...A shortwave trough is passing
through western Canada this morning placing the Pacific Northwest
under a northwest flow. Its main impacts will be some breezy winds
and cooler temperatures today close to near normal. Strongest winds
will be confined to the eastern Columbia River Gorge and the
Kittitas Valley with sustained 20-25 mph and gusts 30-35 mph.

A flat ridge of high pressure will begin to move over the region
from the eastern Pacific late today through Saturday. This will
bring lighter winds to the entire forecast area while keeping
temperatures near normal.

Another weak upper level trough will move into western Canada on
Sunday. There could be a few light showers in the central Washington
Cascades otherwise conditions remain dry. It will bring another
increase in breezy winds mainly along the east slopes of the
Cascades and most noticeably to the eastern Columbia River Gorge and
Kittitas Valley similar today todays wind speeds.

LONG TERM...Monday through Friday...The long term remains quiet
with high pressure ridging taking control of our region, bringing an
extended period of null precipitation chances and above normal
temperatures before shifting eastwards with temperatures then
expected to return back to near normal, albeit with precipitation
still locked to the western side of the Cascades.

Monday begins with the aforementioned upper ridge extending from the
Pacific over our region, and then continuing to shift eastwards
through the middle of the week. This will allow for a dry and benign
start to the work week while temperatures steadily increase. Highs
for our population centers begin in the upper 70`s to the low 80`s
on Monday, but by Wednesday most locations will be in the mid 80`s
and portions of the Columbia Basin may even be flirting with 90
degrees. The NBM overall isn`t excited about the prospect about us
getting quite that warm though, with only a 15-20% probability of
highs 90+ on Wednesday.

Meanwhile on Wednesday, the upper low will continue to shift
eastwards as a deep trough swings down from the Gulf of Alaska
region and across the PacNW and eastern Canada. The majority of the
energy from this system should stay north of us in Canada itself,
but ensembles indicate that our flow becomes more zonal thanks to
the troughing, helping to bring our temperatures back down closer to
near normal by next Friday. Unfortunately this flow does mean any
moisture coming onshore is going to get stuck on the windward side
of the Cascades, possibly making it just over the crests, but don`t
expect much with only a slight chance to chance of scattered showers
Wednesday evening through Friday morning on the lee side of the
mountains. Overall, there is moderate to high confidence (60-70%) in
the forecast, with confidence lowering towards the end of the period
as ensemble clusters show some variation in how we can expect the
above systems to evolve, but not enough to significantly drop
expectations. Should be a quiet week of warmer fall temperatures
overall. Goatley/87



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  71  41  71  43 /   0   0   0   0
ALW  73  46  74  46 /   0   0   0   0
PSC  75  47  76  49 /   0   0   0   0
YKM  76  43  75  46 /   0   0   0   0
HRI  75  45  76  46 /   0   0   0   0
ELN  71  42  75  47 /   0   0   0   0
RDM  71  36  72  39 /   0   0   0   0
LGD  68  40  71  41 /   0   0   0   0
GCD  71  37  72  40 /   0   0   0   0
DLS  74  47  79  50 /   0   0   0   0

&&

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

$$

SHORT TERM...91
LONG TERM....87
AVIATION...90