600
FXUS66 KPDT 011107
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
407 AM PDT Thu Oct 1 2026

.KEY MESSAGES...
- Upper level high pressure building over the region through
  next week, with dry conditions prevailing

- Temperatures begin to slowly increase today, with peak
  temperatures expected early next week (temperatures 5 to 15
  degrees above normal)

- Light, diurnally driven winds will prevail each day

&&

.DISCUSSION...
Nighttime satellite imagery tonight shows decks of
cirrus moving east across the northern two-thirds of the
forecast area, while mid level stratus over the Yakima/Kittitas
valleys peaks through breaks in the cirrus.

Through the middle of next week, ensemble and deterministic
model guidance stay in great agreement of the PacNW remaining
under the influence of upper level ridging or zonal flow aloft.
Through Friday night, the upper level ridge will remain quite
flat over the PacNW due to separate shortwave passages through
southern BC Thursday and Friday (confidence 75-90%). Meanwhile,
the upper level ridge will amplify over the eastern Pacific
during this period, then slide inland over the weekend
(confidence 70-85%). Monday the ridge axis will push east of
the PacNW as an upper trough slides into northern BC, with zonal
flow developing overhead and high pressure aloft to the south
(confidence 65-70%). By Tuesday through Wednesday, ensemble
guidance is in great agreement of upper level ridging building
back over the PacNW then amplifying poleward. Through Monday,
temperatures will be on a gradual increase, with peak afternoon
temperatures in the upper 70s to mid 80s Monday (confidence
65-75%). Temperatures will drop a couple degrees into Tuesday,
but expect high temperatures to remain in the upper 70s to low
80s. Conditions are expected to remain dry into middle of next
week with light, diurnally driven winds each day. The exception
will be Monday, where breezy winds (15-20 mph with gusts to
around 30 mph) will develop through the Cascade gaps as surface
pressure gradients slightly strengthen in response to the upper
trough passing to the north. Lawhorn/82

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...VFR conditions to
prevail through the period. CIGS around 6kft AGL or higher will
dissipate around 18Z at sites YKM/PSC. Winds will be light and
diurnally/terrain driven through the period.

&&

.Preliminary Point Temps/PoPs...
PDT  74  46  78  48 /   0   0   0   0
ALW  75  52  78  53 /   0   0   0   0
PSC  77  46  81  47 /   0   0   0   0
YKM  74  49  80  49 /   0   0   0   0
HRI  76  46  80  49 /   0   0   0   0
ELN  69  45  75  45 /   0   0   0   0
RDM  77  41  80  41 /   0   0   0   0
LGD  76  48  81  47 /   0   0   0   0
GCD  81  47  82  47 /   0   0   0   0
DLS  80  53  83  52 /   0   0   0   0

&&

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

&&

$$

DISCUSSION...82
AVIATION...82