881
FXUS66 KPDT 311104
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
404 AM PDT Mon Aug 31 2026

.KEY MESSAGES...

- Drying and warming trend will continue through early Tuesday
  as upper level high pressure moves over the region

- A series of upper level low pressure systems will bring
  periods of rain, breezy westerly winds, and isolated
  thunderstorm chances Tuesday into Friday

&&

.DISCUSSION...


Short term upper ridging will influence the weather across the
region Today leading to a day of warmer temperatures and low
relative humidity area-wide. Widespread 80s are expected highs
This Afternoon with cooler 70s in the foothills and mountain
zones. Surface high pressure will lead to light northeast winds
across WA (slightly breezy over the Oregon Columbia Basin) and
light south winds over the the John Day Basin and areas south.

HREF showed up to about 250 j/jg mean MUCAPEs across limited
reach of the eastern Blue Mountains/Wallowas Tuesday afternoon
with limited, less than 15% chances for lightning between about
18z and 23z especially over Wallowa co.

Chances for wetting rains are in the the 60 to 85% confidence
range for the 24 hours ending 00z Thursday across the eastern
mountains and the the Cascades eastern slopes. Low end CWRs
increase to Likely (60% even across the Columbia Basin and
higher) and moreso across the entire forecast area by the end
of the day Thursday. A look at expected 2 day combined rain
(Wed/Thur) looks like near a wetting rain over the WA Columbia
Basin, to near a quarter inch of rain over the foothills of the
Blues, central Oregon...to as much as one half to three quarters
of an inch over the Blue Mounties and one inch or more along
the Cascade Crest.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...

Clear sky over the entire region will lead to VFR conditions
with light winds under 10 knots. Gusts to around 20 to 25 kts
will develop at DLS after midnight as a system approaches the
region with scattered to broken high clouds overnight.

&&

.FIRE WEATHER...

Minimum RH values will range from the low 20s across the
Kittitas, Yakima Valleys and the Cascade east slopes, and around
20 percent and less every where else. More breezy winds are
expected Tuesday though the Oregon Columbia Basin and the
Columbia River Gorge/Kittitas and Yakima valleys. No
significant areas of combined probabilities for red flag
(critical low rh and wind) shows up in the forecast This Week.
Chances for wetting rains increase Wednesday through Thursday.


&&

.Preliminary Point Temps/PoPs...
PDT  86  51  83  50 /   0   0   0  50
ALW  89  57  84  55 /   0   0   0  50
PSC  89  53  87  51 /   0   0   0  40
YKM  85  59  87  56 /   0   0   0  30
HRI  88  54  86  50 /   0   0   0  40
ELN  80  54  82  49 /   0   0   0  40
RDM  87  45  78  39 /   0   0  30  40
LGD  88  53  86  48 /   0   0  10  50
GCD  91  54  86  50 /   0   0  10  50
DLS  88  60  79  55 /   0   0   0  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...None.
OR...Air Quality Alert until noon PDT today for ORZ041-505-506-
     509>511.

&&

$$

DISCUSSION...71
AVIATION...71
FIRE WEATHER...71