565
FXUS66 KPDT 311114
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
414 AM PDT Sun May 31 2026

.KEY MESSAGES...

- Dry conditions and warming temperatures into the middle of the
  week

- Mountain showers and thunderstorms return Wednesday, then
  potentially Friday into the weekend

&&

.DISCUSSION...Today through Early Wednesday: Water Vapor
satellite imagery tonight shows the upper trough over the
northern Rockies, with nighttime satellite imagery showing high
cloud decks over far northeast OR and southeast WA.

The trend amongst ensemble and deterministic guidance today is
for a weak, broad area of low pressure to develop over the
northern Rockies with a ridge building offshore the
PacNW. Tuesday through early Wednesday, the ridge will slide
over the PacNW, bringing temperatures into the upper 70s to mid
80s in the lower elevations. Otherwise, conditions will remain
dry with locally breezy afternoon winds.

Wednesday through Saturday: Ensemble guidance is in good
agreement of an upper shortwave trough sliding across the PacNW
Wednesday, though there remains some uncertainty in timing and
strength of this feature. While the main consensus is for a
return of mountain showers and breezy lowland winds into
Thursday morning, some solutions (22% of members) favor a
stronger shortwave that will bring area wide showers that will
persist through Thursday afternoon. Otherwise, this pattern
would also favor a return of afternoon/evening isolated
thunderstorms over the mountain areas Wednesday.

Dry conditions will return to the area after the shortwave exit
Thursday, but breezy to locally gusty Cascade gap winds will
persist(confidence 45-60%). Ensemble guidance is in agreement
that an upper low will arrive offshore the PacNW Friday then
push inland sometime Saturday, though there is uncertainty in
timing. That said, the trend amongst ensembles is that the
upper low will produce showers across the Cascades Friday
afternoon and overnight, with showers spreading to the eastern
mountains sometime Saturday (confidence 40-60%). Otherwise, the
upper low arrival and subsequent passage will produce breezy
winds across the lower the elevations (confidence 45-65%).
Lawhorn/82

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...VFR conditions to
prevail through the period. Winds will be light, 12kts or less,
and diurnally/terrain driven through the period. Lawhorn/82

&&

.Preliminary Point Temps/PoPs...
PDT  71  45  76  48 /   0   0   0   0
ALW  72  50  76  52 /   0   0   0   0
PSC  77  48  80  51 /   0   0   0   0
YKM  77  48  80  52 /   0   0   0   0
HRI  75  47  79  51 /   0   0   0   0
ELN  71  45  75  49 /   0   0   0   0
RDM  67  34  73  41 /   0   0   0   0
LGD  68  41  72  44 /   0   0   0   0
GCD  70  37  75  42 /   0   0   0   0
DLS  76  49  83  57 /   0   0   0   0

&&

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

&&

$$

DISCUSSION...82
AVIATION...82