765
FXUS66 KPDT 272257
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
357 PM PDT Sat Jun 27 2026

.KEY MESSAGES...
- Isolated thunderstorms along Oregon Cascades and eastern
  mountains this afternoon

- Gusty winds developing in the Kittitas Valley Sunday afternoon

- Below-normal temperatures, breezy to locally gusty west
  winds, and occasional mountain showers through the week

&&

.DISCUSSION...
Water vapor satellite imagery this afternoon shows
the center of an upper low has come onshore, though regional radar
imagery so far today has shown shower activity has mostly been
focused outside of the forecast area. Shower activity across
the Cascade crest/east slopes and across the eastern mountains
will develop over the next couple hours as the low continues to
push inland. Increasing surface instability and modest low to
mid level lapse rates will also allow for a few showers to
develop into isolated thunderstorms through this evening.
Otherwise, breezy west to northwest winds have developed through
the Cascade gaps into the Columbia Basin today.

The upper closed low pushing into the PacNW today will start the
prolonged trend of upper level troughing over the PacNW through
most the next week. The upper low will track east across the
region through Monday, with the main shower activity tied to a
series of shortwaves rounding the low both days. That said,
shower activity will mainly be confined to portions of the
Cascades, Northern Blues, and Wallowas through this period, with
best chances over the Wallowa mountains. Cluster ensemble
guidance is in good agreement of shortwave troughs diving down
the AK/BC coastlines and across the PacNW Tues/Wed and Thursday,
which will bring another round of light mountain rain showers
across the forecast area those days (confidence 55-75%).

As mentioned earlier, breezy winds have developed in the lower
elevations today, and are expected to persist through much of
the week as the troughing pattern holds over the PacNW. The
strongest winds of the week will develop tomorrow afternoon as
a surface low develops in northern MT, resulting in a
tightening cross-Cascade pressure gradient. Winds will generally
be 15-30 mph with gusts up to 40 mph, however winds through the
Kittitas valley are expected to increase to 25-35mph and gusts
to around 50 mph tomorrow (confidence 75-85%). Otherwise, daily
winds will be 15-25 mph with gusts to around 35 mph throughout
the week.

Lastly, the persistent trough pattern will keep temperatures
much cooler than normal through the week, with afternoon
temperatures generally 5 to 15 degrees below normal (confidence
60-75%). This means that afternoon temperatures in the lower
elevations will be in the 70s, with locally 80s, throughout much
of the week. In the mountains, mid-elevations will generally be
in the upper 50s to 60s, with lower to mid 50s in the high-
elevations. Lawhorn/82

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Westerly winds will remain breezy across the region this
forecast period. Most sites are seeing winds above 12 kts with
gusts nearing 20-30kts. DLS/YKM are both also expecting some
wind shear WS019/28035KT for DLS and WS020/31040KT for YKM.
Lastly, BDN/RDM have a 30% chance or less of isolated vicinity
thunderstorms after 00Z through 03Z.

&&

.Preliminary Point Temps/PoPs...
PDT  46  73  47  72 /  10  10  10   0
ALW  52  74  52  72 /  10  10  10  20
PSC  50  81  50  78 /   0   0   0   0
YKM  49  81  51  81 /  10  10   0   0
HRI  48  77  48  75 /   0   0   0   0
ELN  46  71  48  72 /  10  10   0   0
RDM  36  67  35  70 /  20   0   0   0
LGD  44  66  45  69 /  30  20  10  10
GCD  39  66  40  71 /  50  20  10   0
DLS  52  73  52  72 /  10   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from 10 AM to 11 PM PDT Sunday for WAZ026.
OR...None.

&&

$$

DISCUSSION...82
AVIATION...90