778
FXUS66 KPDT 132210
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
310 PM PDT Thu Aug 13 2026

.KEY MESSAGES...

- Multiple Red Flag Warnings in effect for abundant lightning
  today through tomorrow

- Isolated to scattered thunderstorms and showers will develop
  over the Cascades and eastern mountains through Saturday, with
  gusty outflow winds possible

- Smokey conditions will continue while temperatures will be
  near normal through the week

&&

.DISCUSSION...Water vapor imagery shows upper level troughing
over the PacNW this afternoon, with a shortwave offshore
Vancouver Island poised to drop into the trough later tonight.
Area radar and visible satellite imagery shows isolated to
scattered thunderstorms developing across portions of
central/northeast OR and the WA Cascade east slopes. This
activity will continue through this evening across most areas as
a shortwave impulse rides the southwest flow aloft. The
shortwave will tap into increasing monsoonal moisture (PWATS
~0.75in) and increasing instability (MUCAPE 250-750J/kg and low
level lapse rates 9-10C). Convection will continue overnight
across the eastern mountains as instability lingers and the
shortwave impulse continues to push northeast.

Troughing will slowly push offshore through Saturday, all the
while keeping south to southwest flow over the PacNW. Daily
shortwave impulses will tap into the increased monsoonal
moisture and surface instability, resulting in rounds of
isolated to scattered thunderstorms developing over the Cascades
and eastern mountains. For tomorrow, the best instability
(300-600J/kg, low level lapse rates 9-10C) will be present over
the WA Cascade east slopes and from the Elkhorn crest to
Wallowa county. Expectation is that abundant lightning and gusty
outflow winds will redevelop in these areas, producing a
critical fire weather threat. By Saturday, the best activity
will be focused over the Blue mountains, but an increase in
moisture across the region will result in higher wetting rain
potential with any developing showers and thunderstorms.
Nonetheless, there is moderate confidence (60-70%) of elevated
fire weather conditions developing owing to lightning potential
outside of rain cores and gusty outflow winds.

Sunday into the middle of next week, ensemble cluster solutions
are still in disagreement on the evolution of the overall
synoptic pattern. While there is good agreement (55-65%
confidence) in a closed low developing well offshore the PacNW,
ensemble clusters either favor the closed low strengthening and
reminding offshore through Wednesday, or the low weakening
with an open wave trough sliding across the PacNW into the
middle of the week. Through Tuesday, either solution still
places a mid to upper level southwest flow over the PacNW, which
will result in continued chances (15-30%) of isolated to widely
scattered showers/thunderstorms over the mountains.

Otherwise, the lack of strong system moving over the region will
prevent smoke from clearing out, with smoke from area wildfires
to continue to inundate portions of the forecast area into next
week. Lawhorn/82


&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...Smoke will bring down
visibility marginally to about 4 to 5sm in central Oregon,
while being less impacting in most other terminal locations.
Winds remain light across the region Today and Tonight. Mountain
showers and thunderstorm development is anticipated to start by
mid afternoon, and a TEMPO group was added to central Oregon
terminals where the CAMS do indicate scattered convective
activity from mid afternoon into the evening.

&&

.FIRE WEATHER...Increased surface moisture and instability across
the region will bring isolated to scattered thunderstorm threat
into the weekend. The abundant lightning threat today will be
along the WA Cascade east slopes, central OR, and the eastern OR
mountains. The threat will shift out of central OR tomorrow and
Saturday, but remain in the other two areas. Gusty outflow winds
will also be a concern from stronger storms that develop. Winds
will be mostly light to locally breezy through the weekend.

&&

.Preliminary Point Temps/PoPs...
PDT  54  87  55  89 /   0   0   0  30
ALW  59  88  60  91 /   0   0   0  30
PSC  58  90  58  93 /   0   0   0  10
YKM  60  87  59  91 /  10  10  10   0
HRI  58  90  59  92 /   0   0   0  10
ELN  57  82  56  86 /  20  30  10  10
RDM  48  85  50  87 /  10  20  10  10
LGD  55  86  55  87 /  40  20  10  60
GCD  54  85  54  88 /  70  40  10  60
DLS  63  90  63  91 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until 3 PM PDT Friday for WAZ026>030-521>523.
     Red Flag Warning until 9 PM PDT this evening for WAZ695.
     Fire Weather Watch from Friday afternoon through Friday
     evening for WAZ695.
OR...Air Quality Alert until 3 PM PDT Friday for ORZ041-049-050-502-
     503-505-506-509>511.
     Red Flag Warning from 5 AM to 7 PM PDT Friday for ORZ694.
     Red Flag Warning until 7 PM PDT Friday for ORZ695-697-699.
     Red Flag Warning until 9 PM PDT this evening for ORZ700-705.
     Red Flag Warning until 5 AM PDT Friday for ORZ696-698.

&&

$$

DISCUSSION...82
AVIATION...71
FIRE WEATHER...82