304
FXUS66 KPDT 092240
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
340 PM PDT Sat May 9 2026

.KEY MESSAGES...
- Dry conditions will remain dry and warm into the midweek

- Another round of breezy conditions will develop Sunday,
  strongest winds in the Cascade Gaps

- Mountain rain shower and isolated thunderstorm chances return
  midweek

&&

.DISCUSSION...Tonight through Monday: Upper level ridging has
redeveloped over the region, with satellite showing cirrus
spilling into the northern half of the forecast area this
afternoon. Winds have been light, with dry conditions across
much of the area.

The upper ridge will keep conditions fairly dry while
temperatures remain around 5 to 15 degrees above normal across
the much of the region. These conditions will continue through
Monday as the upper ridge continues to influence the region.
While winds will be light the remainder of today and Monday, a
shortwave passing through the ridge on Sunday will bring another
round of widespread breezy conditions (15-25mph with gusts
25-40mph). Once again there is growing concern of stronger winds
through the Kittitas valley, however confidence is only moderate
(55-65%) in wind gusts reaching 45 mph Sunday afternoon.

Tuesday through Friday: Ensemble cluster guidance is in good
agreement in the breakdown of upper level ridging over the
region Tuesday, with a deeper south to southwest flow
developing as well as a signal for thermal troughing to develop
into eastern and central OR. This will promote a modest increase
in high temperatures over the region, with upper 80s to mid 90s
in the lower elevations, and mid 70s to mid 80s in mountain
valleys. In addition to warming temperatures, instability across
the mountainous terrain will also introduce a slight chance
(15-25%) of showers and isolated thunderstorms for Tuesday
afternoon into the evening.

Tuesday night through Friday, disagreement grows amongst
ensemble guidance in the evolution of the synoptic pattern. The
majority consensus (~60 to 70% of members) is that an upper
low/trough offshore will kick inland sometime late Tuesday into
Wednesday. A northern track of the low feature will bring shower
and isolated thunderstorm chances to most mountain areas and the
Blue Mountain foothills, while a southern track keeps the best
chances across central and eastern OR. Following the trough
passage, a quick transient ridge will bring dry conditions
across the area Wednesday night into Thursday morning
(confidence 45-60%). Thursday afternoon into Friday, ensemble
cluster guidance depicts upper level troughing developing
offshore, with 50% of members favoring shower chances across the
Cascades and eastern mountains, and the other 50% favoring
shower chances only along the Cascade crest. Overall forecast
confidence in timing and extent of shower chances is low-
moderate (25-40%) during the Wednesday through Friday period.
Lawhorn/82

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...VFR conditions to
prevail through the period. Winds will remain light, 12kts or
less, at sites PDT/RDM/BDN/YKM/ALW/PSC through the period. Site
DLS will see winds increase to around 20kts with gusts to around
30kts around 17Z. Lawhorn/82

&&

.FIRE WEATHER...High pressure will remain over the region with
dry and warming conditions persisting at the surface. Breezy
west to northwest winds will develop Sunday, with strongest
winds through the Cascade gaps. A breakdown in high pressure
Tuesday will result in an increasing unstable airmass over
portions of central Oregon and the eastern mountains. Afternoon
relative humidities will be mostly in the teens to mid 20s, with
single digits in central Oregon this afternoon and again
Tuesday afternoon.

&&

.Preliminary Point Temps/PoPs...
PDT  48  78  46  77 /   0   0   0   0
ALW  51  79  50  77 /   0   0   0   0
PSC  50  84  50  81 /   0   0   0   0
YKM  51  83  46  80 /   0   0   0   0
HRI  49  82  48  79 /   0   0   0   0
ELN  48  75  43  76 /   0   0   0   0
RDM  45  81  38  83 /   0   0   0   0
LGD  44  84  43  79 /   0   0   0   0
GCD  43  89  43  84 /   0   0   0   0
DLS  53  77  48  82 /   0   0   0   0

&&

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

&&

$$

DISCUSSION...82
AVIATION...82
FIRE WEATHER...82