968
FXUS66 KPDT 062140
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
240 PM PDT Sun Sep 6 2026

.KEY MESSAGES...
- Shower and thunderstorm chances through this evening, with
  decreasing chances on Monday.

- Dry weather through much of the week with seasonable
  temperatures.

- Potential for another upper trough and precipitation next
  weekend.

&&

.DISCUSSION...
The persistent upper low that has been over the Pacific
Northwest will begin to move eastward tonight and will be well
east of the region on Monday. However, some troughing will
remain over the area and will keep unsettled conditions, mainly
over the eastern Oregon mountains on Monday, with everywhere
else remaining dry.

By Tuesday, and through much of the week, the area will be under
a split flow regime, with a more westerly flow moving in by
Thursday.

On Friday, another upper low will drop down from the northwest,
and bring another chances of showers, and possibly some
thunderstorms, mainly to the mountains. This low will cross the
region on Saturday and exit on Sunday. Unlike the current low,
this looks to be a fast moving progressive low.

Latest radar showed isolated to scattered showers. Satellite
imagery showed abundant cloud cover and many areas were
struggling in the 50s and lower 60s, though the Columbia Basin
was close to 70 degrees. Cloud cover is affecting thunderstorm
development, but if we are able to get some sufficient breaks
later this afternoon, the most likely areas for thunderstorm
development would be from the northern Blue Mountains eastward.


In areas of heavy rain, the could be 0.25 to 0.50 inches, but
most places will see less than 0.25 inches.

Monday will see breezy winds, in the 25 to 30 mph range,
possibly as high as 35 mph across the Cascade Gaps, Kittitas
Valley, Simcoe Highlands and the Columbia Basin and Gorge.

Another breezy period will be Thursday across the same areas in
advance of the next trough winds will be similar (possibly a bit
higher), though RH values will be lower on Thursday. Areal
coverage of wind gusts are a bit more on Thursday while
probabilities of wind gusts >= 25 mph >80 percent both days.

High temperatures will remain 10 to 15 degrees below normal on
Labor day before rising to near seasonal normals for much of the
week. Highs will ten drop below normal again Friday and Saturday
as the next trough moves through. the ECMWF EFI has 0.8 to 0.9
below normal for Monday across mainly central and eastern
portions of Oregon.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Periods of light to moderate rain showers continue through the
next few hours. Rain will dry out as we head into the later
afternoon to early evening hours. Guidance is picking up wind
getting breezier in DLS and ALW tomorrow morning with max wind
gusts of 15 to 25 knots. For the rest of the today, VFR
conditions prevail but there has been some reported MVFR
conditions temporarily lasting which I expect to not last long
as the precip moves out of the area. There is still a low
probability (10 to 20 percent) of some MVFR conditions moving in
and out at the TAF sites.

&&

.Preliminary Point Temps/PoPs...
PDT  47  71  42  76 /  20  20   0   0
ALW  51  73  49  78 /  50  30   0   0
PSC  50  77  48  80 /  10  20   0   0
YKM  52  77  51  79 /  20   0   0   0
HRI  50  75  48  79 /  10  20   0   0
ELN  48  71  45  77 /  20   0   0   0
RDM  37  68  37  75 /  30   0   0   0
LGD  45  68  41  74 /  90  40  10   0
GCD  44  67  41  76 /  70  10   0   0
DLS  53  75  51  80 /  20   0   0   0

&&

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

&&

$$

DISCUSSION...77
AVIATION...95