253
FXUS66 KPDT 031023
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
323 AM PDT Wed Jun 3 2026

.KEY MESSAGES...

- Light showers and afternoon isolated storms possible today.

- Breezy afternoon winds today and through week, peaking Friday.
  *Wind Advisories Issued*

- Cooling trend through Saturday, warming early next week.

&&

.DISCUSSION...
Current radar and infrared satellite imagery showing pockets of
light returns across Central Oregon as mid-to high level clouds
slowly move across the Columbia Basin. This is in response to
an approaching upper level shortwave that has tapped into some
mid-latitude moisture to allow for light showers to extend east
of the Cascades throughout the day. The best chances (30-50%)
for showers will be along the east slopes of the Cascades and
Central Oregon through this afternoon, and through Grant, Union,
and Wallowa counties this afternoon through the evening. These
counties will also experience the potential for isolated
thunderstorms as the incoming shortwave erodes the backside of
the exiting transient ridge. The HREF advertises surface CAPE
values of 150-350 J/kg with 0-6km shear of 30-35kts, which is
supportive of convective activity as also indicated by the Storm
Prediction Center including the area in their General
Thunderstorms (0 of 5) category. However, 700-500mb lapse rates
do still look marginal (6-6.5C/km) and decrease through the
afternoon and evening. Thus, it is expected that isolated, sub-
severe thunderstorm cells will develop over our central and
northeastern Oregon zones this afternoon and evening.

The incoming shortwave will also lead to the tightening of a
pressure gradient along the Cascades, due to the interaction
with the exiting transient ridge that brought warm and sunny
conditions to the area on Tuesday. This enhanced gradient will
impact much of the region with increased winds as the cold front
passes mid-afternoon with gusts of 25-35 mph possible across
the Blue Mountain foothills and the Columbia Basin. The highest
winds will be experienced across the Simcoe Highlands and
Kittitas Valley as west-northwest sustained winds of around 30
mph and gusts up to 50 mph will be possible. As a result, Wind
Advisories have been issued from 1 PM today through midnight
tonight. The NBM highlights a 70-80% chance of 45 mph gusts or
greater through the Simcoe Highlands. In addition, the NAM and
SREF indicate a 5-6mb pressure gradient between PAE and PSC,
hinting to advisory-level winds through the Kittitas Valley.

Today`s shortwave is spinning off a stronger upper level low
pressure system currently located in the Gulf of Alaska. This
low pressure will slowly move south along the coast of British
Columbia Thursday and early Friday before moving onshore Friday
evening and passing through the area on Saturday. Moisture looks
to be lacking with this event and stays confined at elevation
across the Cascades. However, a building upper level ridge to
our east and associated surface high pressure will lead to
windy conditions across much of the area. The GFS and NAM
suggest a pressure gradient of 8-10mb between PQR and OTX, which
would related to advisory-level winds across the Simcoe
Highlands and north-central Oregon. The NBM shows a 70-80%
chance of this occurring Friday afternoon and evening. Breezy
winds are also expected across the Columbia Basin, Blue Mountain
foothills, and Yakima/Kittitas Valley, but sub-advisory winds
are currently expected. Consistency in guidance is improving as
59% of LREF ensemble members suggest winds near or slightly
above the current forecast, with 41% of members hinting at an
earlier or weaker incoming system. Another result of the
dropping system will be cooling temperatures, as highs drop from
the upper 70s to low 80s today into the upper 60s to low 70s
Saturday across the Lower Columbia Basin, Blue Mountain
foothills, and portions of Central Oregon. These Saturday values
are 8 to 10 degrees below normal for this time of year. 75

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
VFR conditions currently across all sites, which will stay the
course through the period. Ceilings will continue to drop this
morning to around 5kft for all terminals, improving to 25kft
through the evening. Breezy wind gusts of 20-30kts will impact
KDLS/KPDT/KRDM/KBDN/KYKM this afternoon and evening. 75

&&

.FIRE WEATHER...
Elevated fire weather concerns are anticipated on Friday across
the Columbia Basin (Fire Weather zone WA691) due to a
combination of breezy to windy conditions and afternoon relative
humidity (RH) dropping to 20-25%. Compounding this threat is a
dry baseline; Thursday afternoon`s low RH (15-25%) will be
followed by only moderate to good (50-65%) overnight humidity
recoveries heading into Friday morning. Fuels in zone WA691 have
been declared ready and receptive. While these compounding
factors suggest a Red Flag Warning may be warranted for Friday,
no official products have been issued at this time. 75


&&

.Preliminary Point Temps/PoPs...
PDT  78  47  75  47 /  10  10   0   0
ALW  79  53  76  52 /  10  10   0   0
PSC  83  52  80  49 /  20  10   0   0
YKM  80  48  80  48 /  40   0   0   0
HRI  81  50  78  50 /  10   0   0   0
ELN  73  45  72  44 /  50   0   0   0
RDM  74  37  76  40 /  20   0   0   0
LGD  76  45  74  43 /  40  20   0   0
GCD  78  42  77  42 /  40  10   0   0
DLS  78  53  77  52 /  20   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from 1 PM this afternoon to midnight PDT tonight
     for WAZ026-521.
OR...None.

&&

$$

DISCUSSION...75
AVIATION...75
FIRE WEATHER...75