744
FXUS66 KPDT 010517
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1017 PM PDT Mon Jun 30 2025

.Updated for Aviation...


.AVIATION...
06Z TAFS...VFR conditions are expected through the TAF period.
Winds are expected to be less than 10 kts at most locations.
However, at DLS, RDM and BDN, some afternoon and gusts will occur
once again. At DLS, gusts around 25 kts are expected and at
BDN/RDM gusts in the 15 to 20 kt range are expected. Winds should
decrease during the late evening hours.

&&

.PREV DISCUSSION... /issued 430 PM PDT Mon Jun 30 2025/

Updated Aviation Discussion.

AVIATION...00Z TAFS...VFR conditions currently across all sites,
which will stay the course through the period. Winds will stay light
and below 10 kts for most sites, with the exception of
KRDM/KBDN/KDLS experiencing gusts up to 20-25 kts toward the end of
the period. KRDM/KBDN will also experience gusts up to 20 kts late
this afternoon before dissipating this evening. SCT-BKN ceilings of
20-25kft will build in this evening and overnight as a system
approaching from the south. 75

PREV DISCUSSION... /issued 156 PM PDT Mon Jun 30 2025/

SHORT TERM...Today through Wednesday...Heat returns to the forecast
area as the PacNW finds itself wedged between high pressure ridging
to the north and a cutoff low to the south over California. Such a
setup is ripe for not only hot temperatures through Tuesday, but
also for elevated thunderstorms for central Oregon, spreading
eastward through Wednesday as the northeastward progression of this
low amplifies SW flow and thus moisture advection over the forecast
area.

Not much change in heat headlines, as Heat Advisories remain in
effect for the Basin, Gorge, Yakima/Kittitas Valleys, and north
central Oregon. Tuesday continues to look like the hottest day, with
much of the Basin expected to eclipse the century mark on Tuesday
afternoon. Once high pressure is nudged aside heading into
Wednesday, temperatures are expected to trend toward more seasonable
readings.

Keeping an eye on the shower and thunderstorm threat for central
Oregon starting this evening as a result of SW flow becoming more
prominent over the region. Latest HREF guidance generally keeps
convective activity south of the forecast area tonight, before
ramping up tomorrow afternoon and spreading as far north as the
southern Blues and as far east as the John Day Valley. Bullseye
currently appears to be Deschutes and Crook Counties, at least for
our forecast area. PWATs are on the higher end (0.7-0.9 inches)
owing to strong SW flow aloft, and a slower storm motion would
suggest more of a wetting rain potential, but with convective
parameters as supportive of convection as they are (plentiful mid-
level moisture with MUCAPEs reaching up to 1000 J/kg), have elected
to err on the side of caution and issue a Red Flag Warning for at
least one central Oregon zone (OR700) for dry lightning. QPF falls
off quite a bit to the north of this "bullseye," so am not confident
enough in widespread wetting rains to completely negate the dry
lightning effect. Confidence in wetting rains increases for storms
closer to the Cascades.

On Wednesday, winds increase as high pressure breaks down. Temps
cool, but with the boundary layer still dry from Tuesday`s heat,
winds have the potential to combine with low RHs in the teens to
create critical fire weather conditions. Have opted to issue a Fire
Weather Watch for the Washington Columbia Basin and Kittitas Valley
for Wednesday as a result. RHs do seem high enough to preclude
critical conditions in adjacent zones, and winds/RHs are admittedly
borderline in the watch zones, but the overall setup does at least
support elevated fire spread concerns. Will see how models evolve
with regards to the RH and winds on Wednesday and adjust the Watch
accordingly. Evans/74

LONG TERM...Thursday through Monday...Ensembles suggest the
potential for another shortwave trough to cross through the PacNW on
Thursday, making for another chance for showers and isolated
thunderstorms across mainly the eastern mountains. The thunderstorm
risk will be downplayed, however, due to weakening instability,
stemming from lower lapse rates as this relatively progressive
synoptic pattern shaping up helps stabilize the atmosphere to a
degree.

Ensemble clusters generally suggest a benign pattern heading into
the Holiday weekend, split between a weak zonal or SW pattern, but
neither strong enough to produce shower chances for either the
Cascades or eastern mountains. Expect generally seasonable
temperatures, with winds slackening after Thursday as the
progressive nature of the pattern lightens up. Evans/74

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  64 100  67  93 /   0   0  10  10
ALW  68  99  70  92 /   0   0  10  20
PSC  63 102  66  96 /   0   0   0  10
YKM  65 100  65  94 /   0   0   0   0
HRI  63 102  68  95 /   0   0  10  10
ELN  65  99  65  87 /   0   0   0   0
RDM  57  96  55  87 /   0  10  20  10
LGD  60  96  63  89 /   0   0  10  20
GCD  61  97  60  90 /   0  10  30  20
DLS  68  98  65  85 /   0   0  10   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory until 9 PM PDT Tuesday for ORZ041-044-507-508-510.

     Red Flag Warning from 2 PM to 9 PM PDT Tuesday for ORZ700.

WA...Heat Advisory until 9 PM PDT Tuesday for WAZ024-026>029-521.

     Fire Weather Watch from Wednesday afternoon through Wednesday
     evening for WAZ690-691.

&&

$$

SHORT TERM...74
LONG TERM....74
AVIATION...77