782
FXUS66 KPDT 112115
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
215 PM PDT Fri Apr 11 2025

.SHORT TERM...This afternoon through Sunday night...Relatively
quiet weather is forecast through the short-term period. The main
tangible weather worth discussing includes the following:

1) Slight chance (15%) of thunderstorms SE Deschutes, Crook, and
Grant counties with a very slight chance (5-10%) for Union and
Wallowa counties late this afternoon through evening.
2) Breezy to windy westerly winds through the Kittitas Valley
today and Saturday, with mostly breezy conditions elsewhere.
3) Near- to below-freezing morning low temperatures across the
lower elevations Sunday and Monday mornings.

Near-term thoughts: An upper-level shortwave trough is
approaching the Pacific Northwest from the west. Ahead of the
trough, modest surface-based instability (up to 500 J/kg) is
developing to our south in Klamath and Lake counties. Weaker
instability (up to 250 J/kg) extends farther north into southeast
Deschutes, Crook, Grant, and Harney counties. As the afternoon
progresses, daytime heating should facilitate a modest increase in
surface-based instability (predominantly 250-500 J/kg) across the
aforementioned counties. Of note, the convective temperature from
this morning`s sounding at MFR was 59 degrees, and forecast
soundings from HREF members indicate convective temperatures from
the upper 50s to lower 60s on the east side of the Cascades this
afternoon. Current surface observations are in the mid-50s to
lower 60s, but surface dew points are drier than many HREF members
forecast (not uncommon) so thinking is actual convective
temperatures may be closer to the lower to mid-60s. Dynamic
forcing should increase later this afternoon through evening as
the upper trough starts to swing onshore, so isolated
thunderstorms still appear possible. However, confidence in all
variables lining up is medium (50%), especially since quite
extensive cirrus remains draped over much of the Blue Mountains
region.

Tonight through Saturday, the shortwave trough is progged to track
onshore before exiting to the east by Saturday night. Lingering
mountain rain/snow showers are forecast through Saturday, but any
accumulation will be light.

Winds through the Kittitas Valley may approach advisory criteria
this evening through Saturday, and NBM probabilities suggest a
50-80% chance of maximum gusts reaching or exceeding 45 mph in the
24-hr period from 10PM this evening through 10PM Saturday. Raw
guidance (HREF, ECMWF ensemble, etc.) is not quite as favorable,
but the pattern certainly favors at least breezy west to northwest
winds. Have held off on issuing wind highlights for now due to
insufficient confidence in sustaining advisory criteria.
Elsewhere, winds will be breezy to locally windy through the
Columbia Gorge/Basin and along the Blue Mountain foothills, but
have a low (<40%) chance of reaching advisory criteria.

Looking ahead, a cooler, drier air mass will settle into the
forecast area behind the trough, and all elevations have a chance
of near- to below-freezing temperatures Sunday and Monday
mornings due to anticipated efficient radiational cooling. No
forecast zones are yet eligible for Freeze Warnings this season
(those begin on April 15th), so will not be issuing any highlights
for freezing temperatures. Plunkett/86

&&

.LONG TERM...Monday through Friday...A benign forecast is slated
throughout the long term period. Ridging greets the work week with
warming temperatures across the forecast area. Values will
generally increase 5 to 10 degrees from Sunday`s values. The
warmest values are anticipated across central Oregon where values
will be 10 to 20 degrees above normal, and there is a 40 to 60%
chance of values greater than 70 degrees.

A trough passing through on Tuesday will produce insignificant
impacts across the area. Temperatures will warm across the
Columbia Basin on Tuesday, becoming around 10 degrees above
normal, with a 50-70% chance of values greater than 70 degrees.
The trough axis will move through the forecast area, potentially
creating briefly gusty wind on Tuesday afternoon/evening. The
passage of the trough axis by late Tuesday/early Wednesday will
cause temperatures to drop a few degrees, but still remain above
normal. Ridging returns to the area on Wednesday, with variability
on the amount of amplification the ridge will experience.

This ridge will continue the dry and warm conditions across the
area, with temperatures reaching 10 to 20 degrees above normal by
Friday. Areas of Washington will see a 70-90% chance for
temperatures above 70 degrees by Friday, with a 10-30% chance for
values of 80 or greater. Oregon will see a 30-60% chance of
temperatures of at least 70 degrees by Friday.

Cluster analysis shows good agreement with much of the long term
period. The primary variances remain with the placement and
amplitude of the ridging, which could impact observed
temperatures. Branham/76

&&

.AVIATION...18z TAFs...Widespread VFR conditions at area terminals
through the TAF period. A trough continues to approach the
forecast area today sending moisture over the higher terrain.
Showers and isolated thunderstorms could be possible across
central Oregon (not impacting KRDM or KBDN) through the evening
hours. Surface wind should generally remain less than 15 kts,
though gusty wind (gusts of 20-25 kts) could develop after 12z
Saturday. Branham/76

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  38  57  33  61 /  10   0   0   0
ALW  40  56  35  61 /  10  10   0   0
PSC  40  63  33  65 /   0   0   0   0
YKM  36  59  31  62 /   0   0   0   0
HRI  39  62  33  65 /   0   0   0   0
ELN  36  54  31  60 /   0   0   0   0
RDM  30  57  26  63 /   0   0   0   0
LGD  36  51  29  58 /  40   0   0   0
GCD  36  52  29  61 /  60   0   0   0
DLS  39  59  35  65 /   0   0   0   0

&&

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

$$

SHORT TERM...86
LONG TERM....76
AVIATION...76