501
FXUS66 KPDT 292053
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
153 PM PDT Sat Jun 29 2024

.SHORT TERM...Today through Monday...SW flow aloft is currently
enveloping the forecast area as a broad trough moves into the PacNW.
Much of the region has been enveloped with cloud cover as a result,
which is expected to continue until drier air filters in from behind
the trough passage by early Sunday. Until then, light mountain
showers are possible, primarily for the Washington Cascades and
eastern mountains. Thunderstorms had previously been a concern, but
given the ongoing cloud cover across the area, current thinking is
that any thunderstorm activity that develops today will be very
isolated and short-lived in nature. Latest CAMs suggest that shower
activity will dwindle overnight, with perhaps a few lingering
showers over Wallowa County by daybreak Sunday, but largely ending
by late afternoon Sunday at the latest.

The trough passage will bring in breezy winds Sunday into Monday,
however gusts are expected to be relatively moderate - roughly 30 to
35 mph across our more wind prone areas with widespread 20 to 30 mph
gusts elsewhere. Could see isolated 40+ mph gusts, mainly on Monday,
for the Kittitas Valley and Columbia River Gorge, but winds look to
overall fall short of advisory criteria. Given the marine push
brought about by the trough passage, RHs look to remain above
critical levels as well, so even though breezy conditions will
exacerbate fire spread concerns, critical fire weather conditions
are overall not anticipated.

Temps will be relatively stagnant through the short term, with highs
in the 80s and 70s in the mountains, before a more distinct warming
trend takes place later on in the upcoming work week. Evans/74

.LONG TERM...Tuesday through Saturday...Deterministic models and
ensembles are in good agreement on the 500 mb pattern through much
of the period, though there is some uncertainty in how hot it will
get mainly on Saturday. The upper pattern starts out with a NW flow
aloft on Tuesday with an upper ridge offshore and a trough over SW
Canada. A shortwave will move through the flow across NRN WA
and NRN ID Tuesday night and Wednesday. This will result in breezy
winds in the Cascade gaps both Tuesday and Wednesday afternoon and
evening, but strongest on Tuesday. As of right now the need for wind
highlights looks low (20-30%) with most wind gusts in the 30-40 mph
range mainly Tuesday.

On Tuesday and Wednesday high temperatures will be within 2-3
degrees of normal. However on Thursday as the ridge begins to build
northward and closer to the coast, high temperatures will warm into
the low to mid 90s in the lower elevations.

The ensemble clusters do show some variability for Friday and
Saturday but there is roughly an 80% chance of an upper ridge being
located over the area or just offshore. However there is a
low probability (roughly 10% chance of occurring) alternate scenario
worth mentioning where the ridge breaks down and temperatures cool
to near normal. The warmer scenario from the NBM was used for this
forecast. For Friday and Saturday it looks to be hot with high
temperatures in the mid 90s to around 100 in the lower elevations
Friday, and upper 90s to low 100s on Saturday. Of note, the raw
850 mb temperatures from the GFS support even warmer high
temperatures on Saturday.

With the building heat toward the end of the week the experimental
HeatRisk product is highlighting concerns for sensitive groups
Friday and even more so for Saturday. This situation will have to be
monitored as next week progresses.

With almost no chance of rain (less than 5% chance) and decreasing
afternoon humidities with time (as low as 10-15% Friday and
Saturday), fire weather concerns will be elevated. However winds
will be decreasing with time as the upper ridge builds over the
area, which will help to mitigate the overall threat somewhat. 78

&&

.AVIATION...18Z TAFs (Previous Discussion)...VFR conditions are
highly likely (90% chance or greater) for all sites through the
period. A weak system passing over the region this afternoon and
tonight will result in widespread BKN-OVC mid and high cloudiness.
Cloudiness will decrease late tonight and Sunday morning. The SPC
HREF is developing light showers over KPDT and KALW from roughly
06-10Z so included a tempo group for -SHRA in the TAFS for those
two sites. Winds will be mostly 12 kt or less but some gusts to
20-25 kt are expected this afternoon and evening at KDLS, KRDM and
KBDN. 78

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  59  82  54  81 /  20   0   0   0
ALW  63  86  57  85 /  30  10   0   0
PSC  63  88  59  89 /  10   0   0   0
YKM  56  84  54  85 /  20   0   0   0
HRI  62  87  58  87 /  20   0   0   0
ELN  57  75  54  78 /  30   0   0   0
RDM  49  78  47  79 /  10   0   0   0
LGD  56  78  50  77 /  40  20   0   0
GCD  54  81  49  80 /  40  10   0   0
DLS  61  81  59  81 /  10   0   0   0

&&

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

$$

SHORT TERM...74
LONG TERM....78
AVIATION...78