003
FXUS66 KPDT 082258
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
358 PM PDT Tue Sep 8 2026

.KEY MESSAGES...
- Below-normal temperatures today, then warming to near or above
  normal Wednesday and Thursday.

- Low-medium (20-50%) chance of widespread advisory-level winds
  through the Cascade gaps Thursday, with locally higher
  (60-85%) chances for wind-prone portions of north-central
  Oregon and the Kittitas Valley.

- Friday into Monday brings showers and potential convective
  precipitation.

&&

.DISCUSSION...
The upper-level low-pressure system that brought cool
temperatures and widespread precipitation to the region over the
holiday weekend is ejecting eastward over the ID/MT Rockies, with a
dry northwesterly flow aloft in its wake. Meanwhile, water vapor
imagery reveals an upper-level ridge of high pressure in the
northeast Pacific extending into British Columbia. Farther south,
the remnants of Marie are tracking northward towards another area of
low pressure that is located off the central California coast.
Satellite shows mostly clear skies across the forecast area early
this afternoon, aside from a fair weather cumulus field that is
developing over the Blue Mountains. Temperatures will be a few
degrees below normal today, with predominantly light winds.

Looking ahead, ensemble NWP guidance is in excellent agreement that
the remnants of Marie will merge with the low off the California
coast and retrograde through the week. Heights will rise over the
forecast area as the ridge slides east tomorrow, resulting in near-
normal or above-normal afternoon high temperatures. The ridge will
be suppressed Thursday as a shortwave trough dives south across
British Columbia, resulting in strengthening zonal flow aloft.

Westerly winds will increase in strength on Thursday, and may result
in wind headlines. The NBM indicates a low-medium (20-50%) chance of
advisory-level wind gusts (45 mph or greater) through the Cascade
gaps, with locally higher (60-85%) chances for wind-prone portions
of north-central Oregon and the Kittitas Valley.

Aside from the winds, anticipating another day of near-normal to
above-normal high temperatures Thursday, and a slight chance (15-
25%) chance of showers across the Blue Mountains and their foothills
Thursday afternoon into Thursday night.

Leading into Friday shows the trough entering the Pacific NW region
traveling east through the region up throughout the weekend,
bringing showers and chance for convective precipitation for the
Blue Mountain region. Conditions from Friday into Sunday show
chance Showers, potential convection and near normal
temperatures. While the model clusters, NAM, and GFS are in
agreement of when the trough will arrive they are split on the
NS position of the trough upon arrival, with the favored
position being near the Washington Oregon Border (49.6%
confidence). Chances for precipitation greater than a tenth of
an inch range from 30% - 62% with a slight chances of thunder at
11%.

Monday the clusters show drier and warmer conditions along with a
weak ridge pattern (67% confidence) with low confidence in the
trough lingering, potentially deepening, bringing more showers
and lower temperatures to Western Oregon (33% confidence).

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
VFR conditions prevail throughout the TAF period with clear and
dry conditions. Winds remain light and variable in nature with
most sustained winds less than 12 knots throughout the next
24-hours. Otherwise, no CIG or VIS issues expected.


&&

.Preliminary Point Temps/PoPs...
PDT  47  84  51  83 /   0   0   0   0
ALW  52  84  58  83 /   0   0   0   0
PSC  50  86  54  87 /   0   0   0   0
YKM  53  84  56  83 /   0   0   0   0
HRI  49  86  54  86 /   0   0   0   0
ELN  49  82  55  75 /   0   0   0   0
RDM  41  87  45  83 /   0   0   0   0
LGD  46  84  50  84 /   0   0   0   0
GCD  47  87  51  85 /   0   0   0   0
DLS  56  87  58  82 /   0   0   0   0

&&

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

&&

$$

DISCUSSION...86
AVIATION...95