180
FXUS66 KPDT 150534
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1034 PM PDT Fri Aug 14 2026

.KEY MESSAGES...

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

- Red Flag warning in effect for portions of the Blue Mountains
  and Wallowa County tomorrow

- Isolated mountain thunderstorms continue through early next
  week with a return of breezy winds through the Cascade Gaps

&&

.DISCUSSION...
Water vapor imagery this afternoon shows a pronounced upper low
circulation offshore the CA/OR border with upper level troughing
extending north across the PacNW. Much like yesterday, area
radar and visible satellite imagery show isolated to scattered
showers/thunderstorms that have developed across the Cascade
east slopes, central/southern Blue Mountains, and around the
Wallowa Mountains. Thunderstorm activity will continue through
this evening as a weak shortwave impulse pushes northeast across
the PacNW, with thunderstorm activity mainly staying mainly
across the mountainous terrain. The shortwave will be supported
by modest MUCAPE (250-750 J/kg), low level lapse rates 9-10C,
and PWATS around 0.75 inches. By late tonight into early
tomorrow morning, another shortwave will rise north across the
PacNW, with light showers developing as a result. CAMs are also
showing low MUCAPE (around 100-250 J/kg) lingering across
central and northeast OR, which will bring a low chance (~15%)
of showers producing infrequent lightning strikes.

The shortwave will continue to lift across the PacNW through the
early evening, bringing yet another round of isolated to
scattered thunderstorms across the Cascades, Blues, and Wallowa
County. Modest MUCAPE and low-level lapse rates will aid in
thunderstorm development through the afternoon, especially
across the Blue Mountains and Wallowa County. The biggest change
will be the increase in monsoonal moisture, with PWATs
approaching 1 inch across portions of northeast OR and southeast
WA, allowing thunderstorms to produce heavy rain. That said,
abundant lightning will still be a threat outside of the main
rain cores across the mountainous terrain.

Sunday and Monday, a developing upper level low will retrograde
into the northeast Pacific, stretching upper level troughing
over the PacNW. This will result in mainly isolated
thunderstorms/showers across the mountains in the afternoons. At
the surface, the cross-Cascade pressure gradient will begin to
tighten, resulting in breezy west winds developing through the
Cascade gaps. Winds will strengthen in the afternoons, with the
stronger winds (15-20mph with gusts up to 35mph) developing
Monday afternoon.

Late Monday through Tuesday, there is good agreement that a
shortwave trough diving out of BC will clip the PacNW,
bringing with it increased westerly winds through the Cascade
gaps, but mostly dry conditions.

Wednesday through Thursday, ensemble clusters are in good
agreement of the upper level trough/low remaining offshore, but
are split on the development of upper level ridging extending
into the area. The solutions range from mainly diffluent to
zonal flow persisting over the PacNW with continue dry and mild
conditions, to south to southwest flow which would signal the
potential for isolated shower/thunderstorm activity over the
mountains but continued near seasonable temperatures. Confidence
is low (25-35%) in the afternoon forecast for those days.
Lawhorn/82

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
A weak weather system moving over the Pacific Northwest late
this evening through Saturday afternoon will keep low
chances of precipitation (generally 10-25%) across all sites for
the majority of the period. Best chances (15-25%) are at
PDT/ALW/PSC roughly 15-21Z Saturday.

Outside of breezy westerly gap winds at DLS Saturday afternoon
and evening, anticipating predominantly light winds of 10 kts or
less, albeit with higher afternoon gusts at RDM/BDN and perhaps
PDT. Any showers and thunderstorms that pass over or in the
vicinity of TAF sites will be capable of producing gusty outflow
winds; best chances are at PDT/ALW in the afternoon.

&&

.FIRE WEATHER...
Increased monsoonal moisture and instability across the region
will continue to bring an isolated to scattered thunderstorm
threat through Saturday, with the best chances of abundant
lightning and gusty outflow winds across the Blue Mountains and
Wallowa County on Saturday. Isolated mountain storm chances
(15-25%) will continue Sunday and Monday. Breezy winds through
the Cascade gaps will return Monday and Tuesday next week.

&&

.Preliminary Point Temps/PoPs...
PDT  55  87  56  89 /  10  20   0   0
ALW  60  90  62  91 /  10  30  10   0
PSC  57  92  59  93 /  20  20   0   0
YKM  59  89  61  92 /  10  20  10   0
HRI  59  90  61  92 /  10  20   0   0
ELN  56  85  59  87 /  10  20  10   0
RDM  50  85  50  87 /  20  20  10   0
LGD  55  86  54  89 /  10  70  20  10
GCD  55  88  54  91 /  10  40   0   0
DLS  64  90  64  92 /  20  20   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until noon PDT Monday for WAZ026-522-523.
     Red Flag Warning from noon to 9 PM PDT Saturday for WAZ692-693.
     Air Quality Alert until noon PDT Saturday for WAZ027-521.
OR...Air Quality Alert until noon PDT Monday for ORZ041-503-505-506-
     508>511.
     Red Flag Warning from noon to 9 PM PDT Saturday for ORZ692>695-
     699.

&&

$$

DISCUSSION...82
AVIATION...86
FIRE WEATHER...82