023
FXUS66 KPDT 281735
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
935 AM PST Fri Feb 28 2025

Updated Aviation Discussion

.SHORT TERM...Today through Sunday...An upper-level ridge of high
pressure remains overhead today, and ensemble NWP guidance is in
excellent agreement that it will remain the dominant feature
through Saturday. Thus, there is little in the way of sensible
weather concerns.

A surface pressure gradient between the lower Treasure Valley and
the Columbia Basin will continue to drive locally breezy southerly
to southeasterly winds along the slopes and base of the Blue
Mountains and through the Grande Ronde Valley through Saturday,
but confidence in winds reaching advisory levels is very low
(<10%).

High temperatures will be anomalously warm today, running 5-20
degrees above normal. Portions of the lower elevations of north-
central and northeast Oregon have a 10-30% chance of reaching 70
degrees, and climatologically warm locations within central
Oregon and the John Day Basin have a better chance at 50-70%.
Overnight low temperatures will be near normal except for some
warmer-than-normal temperatures in areas affected by thermal belts
and exposed to southerly to southeasterly winds (mainly slopes
and ridges).

The next weather system from the Pacific is slated to arrive
Saturday night through Sunday. Ensemble spread is still evident
with regard to timing/location/magnitude of the upper-level trough.
Plunkett/86

&&

.LONG TERM...Monday through Friday...Models are in general
agreement as to the weather pattern for next week, though there
are differences between models that grow over time. Fortunately,
these differences don`t appear to impact the forecast very
significantly. Models agree well on Monday in having a trough
centered over southern California and Nevada and a ridge
approaching the Pacific Northwest coast. By Tuesday, model
clusters show the trough east of the Rockies and the ridge having
moved ashore and centered west of the Cascades. The main
difference between clusters is the strength of the ridge. By
Wednesday, model clusters show the ridge centered somewhere over
Idaho though whether it`s over western Idaho or eastern Idaho is
pretty divided. There is also trough offshore approaching northern
or central California and there is a variety of strengths for the
trough. On Thursday, models agree in showing a ridge over the
Pacific Northwest though it is affected by the cutoff low and
trough over either southern California or Arizona though one
cluster with 12 percent of the members has a stronger low off the
central California coast. On Friday, models show the ridge
strengthening as the trough weakens and moves further east the
southern Rockies or Texas. The ridge is amplified by a fairly
strong upper low becoming apparent in the Gulf of Alaska.
Generally, weather looks fairly benign through the week and the
Extreme Forecast Index shows that no unusual weather is
anticipated. Overall, given model differences, forecast confidence
is good initially (50-70 percent) but Wednesday through Friday
confidence drops to below average (40-50 percent).

With the trough to our south on Monday, this should be the wettest
day of the long term though precipitation amounts are down
substantially from previous forecasts. The eastern Oregon
mountains and Oregon Cascades have chance to likely POPs with QPF
amounts of 1 to 2 tenths of an inch in the higher mountains. With
snow levels at around 4000 feet, this gives the higher mountains
up to 1 to 1.5 inches of snow. NBM probabilities only give the
higher mountains a 40-60 percent chance of 1 inch of snow for
Monday and Monday night combined. With the pressure gradient
between high pressure offshore and low pressure to our southeast,
breezy west to northwest winds of 10 to 20 mph are expected in the
afternoon.

Tuesday and Tuesday night, with the ridge moving overhead, models
show a chance of rain and snow showers in the mountains with just
a few hundredths of an inch of QPF and no more than a quarter to
half inch of snow above 4000 feet. The lower elevations have a
slight chance of rain but with no measurable amounts. For
Wednesday through Friday, models keep a chance of rain and snow
showers over the mountains and a slight chance of rain showers
over central Oregon and the Blue Mountain Foothills but only the
Cascade crest region shows any QPF or snow amounts and they are
minor. Models are showing breezy west to northwest winds on
Thursday and breezy southwest winds on Friday but winds speeds are
no more than 10 to 20 mph. Temperatures through the week are in
the lower to mid 50s with upper 30s and 40s in the mountains
though Friday may be a degree or two warmer. Perry/83

&&

.AVIATION...18Z TAFs...Expect VFR conditions with clear skies
and winds less than 10 kts for the next 24 hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  63  34  58  35 /   0   0   0   0
ALW  63  33  56  33 /   0   0   0   0
PSC  61  32  58  35 /   0   0   0   0
YKM  61  32  57  35 /   0   0   0   0
HRI  64  33  58  36 /   0   0   0   0
ELN  55  28  55  31 /   0   0   0   0
RDM  70  30  63  32 /   0   0   0  10
LGD  57  31  55  30 /   0   0   0   0
GCD  66  30  60  31 /   0   0   0  10
DLS  64  33  60  36 /   0   0   0  10

&&

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

$$

SHORT TERM...86
LONG TERM....83
AVIATION...85