596
FXUS66 KPDT 081056
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
207 AM PDT Wed May 8 2024

.SHORT TERM...Today through Friday night...No major weather
concerns are anticipated in the short term period. In fact, it
will be quiet. The forecast area will be between a building ridge
offshore and a large upper low to the east today, leaving us in a
north-northeast flow aloft. There is a slight chance (20%) of
light showers in far eastern Wallowa County today associated with
wrap around moisture, but the upper low is way east over the
northern Plains that any showers will be isolated. The offshore
ridge will amplify and shift to the east while a closed low sets
up over the four corner states, resulting in a rex block across
western Canada and the western U.S. for the remainder of the short
term period. All that means for WA/OR is continued dry with a
warming trend. The inverted surface thermal trough will remain
west of the Cascades Thursday through Friday. If the thermal
trough was farther east, we would anticipate a major warm up.
Afternoon highs on Friday will be around 10-15 degrees above
seasonal average, but not record-breaking temperatures. Wister/85


.LONG TERM...Saturday through Wednesday...The long term will be
characterized by an upper level high pressure ridge to start.
Sunday night into Monday, a few shortwaves will attempt to make
their way across the region beginning Monday bringing with it
slightly cooler temperatures and minimal mountain precipitation.

Saturday through Sunday afternoon models are in firm agreement with
the upper level ridge well overhead. Clusters also show decent
agreement with the upper level ridge, primary difference being with
the amplitude. Dry and warming conditions will dominate with some
areas in the forecast region seeing temperatures nearing the 90s.
Raw ensembles show over 90% probabilities that the Columbia Basin,
the Gorge and portions of the foothills of the Blues will see
temperatures over 85 degrees Saturday decreasing in area to
primarily the Basin Sunday. Temperatures in the mid elevations will
see 70-80% probabilities of upper 70s to low 80s while the higher
elevations will see 60-70% chances of high 60s to low 70s. EFI shows
that these temperatures are above normal for this time of the year
with the signal strongest over the Cascades and the Columbia Basin.

Sunday night through Wednesday models show a ripple of shortwaves
making their way across the forecast region. However, clusters show
a bit of a discrepancy with how these shortwaves will affect the
ridge. If the ridge remains strongly amplified, little will come of
the shortwaves. If the ridge weakens in any way, the upper level
shortwaves could be strong enough to flatten the ridge slightly
bringing a more westerly flow across the region. With this, the NBM
ensembles have taken almost a middle ground with the models. Monday
morning there is a less than 20% probability of 0.01 inches of
precipitation expected along the highest points of the WA Cascades.
As the shortwave continues across the region, probabilities only
increase to under 25%. However, due to the shift to a more westerly
flow, winds are expected to pick up primarily through the Cascade
Gaps. 50-70% of the raw ensembles show winds of 20-25 mph through
the Gorge,  foothills of the Blues, and Kittitas and Yakima Valleys.
EFI shows a steady decline back towards seasonal average by
Wednesday due to the flattening of the ridge and the incoming
shortwaves. However, 70-80% of the raw ensembles keep the Basin,
adjacent valleys, the Gorge and the foothills in the mid to upper
70s, mid elevations in the low to mid 70s and the higher elevations
in the low to mid 50s. Bennese/90


&&

.AVIATION...12Z TAFs...Primary interest this period will be the
winds. Winds will be mostly terrain driven between 05-12 kts with
RDM/BDN seeing gusts to 20 kts through 01-03Z. Otherwise, VFR
conditions will dominate the period with mostly clear skies.
Bennese/90



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  62  40  73  46 /   0   0   0   0
ALW  64  43  78  49 /   0   0   0   0
PSC  72  45  81  52 /   0   0   0   0
YKM  72  42  80  48 /   0   0   0   0
HRI  69  43  79  49 /   0   0   0   0
ELN  69  43  78  49 /   0   0   0   0
RDM  60  34  71  41 /   0   0   0   0
LGD  56  38  71  44 /   0   0   0   0
GCD  57  33  72  42 /   0   0   0   0
DLS  71  47  81  52 /   0   0   0   0

&&

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

$$

SHORT TERM...85
LONG TERM....90
AVIATION...82