498
FXUS66 KPDT 091743
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1043 AM PDT Tue Jun 9 2026

.KEY MESSAGES...
- Showers today into Wednesday morning, mainly Cascades, Blues,
  and Blue Mountain foothills

- Breezy to windy conditions today with Wind Advisories in
  effect for much of the lower elevations

- Warmer, drier conditions Thursday through the weekend

&&

.DISCUSSION...
Water vapor imagery shows several features of interest across
the region this morning. A shortwave trough is tracking
overhead, with numerous mountain waves evident to the lee of the
Cascades. Meanwhile, a closed mid/upper-level low is rotating
upstream in the Gulf of Alaska. These features will drive our
sensible weather for the next couple days, with showers (mainly
across the Cascades, Blues, and foothills of the Blues)
persisting through Wednesday morning.

Widespread breezy to windy conditions are forecast through this
evening across the forecast area, and Wind Advisories are in
effect. Strongest winds have yet to arrive, but will note
surface observations have reported gusts in the 35-60 mph range
overnight, with the strongest winds generally along exposed
terrain and/or higher elevations. KPDT is sampling 30-40 kts
aloft, with a peak around 900-800 hPa.

NBM probabilities of exceedance suggest very high (70-99
percent) chances of reaching or exceeding advisory-level wind
gusts (45 mph or greater) through 11 PM PDT across the foothills
of the Blue Mountains, north-central Oregon, the Simcoe
Highlands, and through the Kittitas Valley and eastern Columbia
River Gorge. Forecaster confidence in these probabilities is a
little lower (70-90 percent) based on the timing of the
strongest winds aloft not coinciding with peak mixing (i.e.
strongest winds are at night), but forecast cross- Cascade
pressure gradients are sufficiently strong (8-12 hPa difference
between PDX and GEG) this afternoon to support wind headlines.
Will note the NBM indicates a low (10-30 percent) chance of
reaching warning-level wind gusts (58 mph or greater) for our
most wind-prone locations.

The remnants of the aforementioned low in the Gulf of Alaska
are expected (80-90 percent confidence) to slide over the
Pacific Northwest overnight through Wednesday, resulting in
continued mild temperatures and rain showers (mainly for the
mountains). Weak instability (CAPE of up to a couple hundred
J/kg) may facilitate an isolated thunderstorm over the eastern
mountains this afternoon, but chances are low (5-15 percent).

Warmer, drier conditions are then forecast Thursday through the
weekend as an upper-level ridge of high pressure will likely
(80-90 percent confidence) build offshore in the Pacific and
eventually shift east into the Pacific Northwest. Ensemble
cluster analysis reveals some differences in the amplitude and
location of the ridge through the weekend, and a low-medium
(30-50 percent) chance of a somewhat cooler, "wetter" pattern
with the ridge axis located well offshore and shortwave
troughing digging into the Pacific Northwest from the north.
This solution would result in near-normal temperatures and light
showers, while the solution with the ridge axis more overhead
would result in hot, dry conditions.

Temperatures are forecast to peak on Monday and Tuesday, with a
50-90 percent chance of >= 90 degrees, and 5-30 percent chance
of >= 100 degrees for the lower elevations. Moreover,
probabilistic HeatRisk guidance indicates a 15-40 percent chance
of Major (level 3 of 4) HeatRisk for the majority of the lower
elevations within the greater Columbia Basin region. This level
of heat affects anyone without cooling/hydration.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...VFR conditions to
prevail through the period. Breezy winds (15-25kts with gusts up
to 40kts) will impact sites through this afternoon, with winds
weakening late this evening and overnight. However, winds
12-17kts will persist at sites DLS/PDT/ALW/PSC overnight. Expect
winds to increase again and gusts to return between 14Z-18Z at
all sites tomorrow. Lawhorn/82

&&

.Preliminary Point Temps/PoPs...
PDT  68  43  68  41 /  10  10  10   0
ALW  67  47  69  46 /  50  20  20   0
PSC  73  45  75  43 /  20   0   0   0
YKM  70  43  74  44 /  10   0   0   0
HRI  70  44  72  43 /  10   0   0   0
ELN  63  39  64  40 /  50  10   0   0
RDM  65  34  67  34 /   0   0   0   0
LGD  63  41  63  37 /  50  30  50   0
GCD  67  37  65  35 /  10   0   0   0
DLS  67  49  70  46 /  20  10   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until 11 PM PDT this evening for WAZ024-026>029-
     521.
OR...Wind Advisory until 11 PM PDT this evening for ORZ041-044-507-
     508.
     Wind Advisory until 5 PM PDT this afternoon for ORZ510.

&&

$$

DISCUSSION...86
AVIATION...82