092
FXUS66 KPDT 142224
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
324 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,
  WA Cascade east slopes, and Wallowa County today and 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 100-250J/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 /00Z TAFS THROUGH 00Z SATURDAY/...Smoke will continue
to have a marginal impact on the visibilities at area terminals
this TAF period, Light winds under 12 knots are expected through
the fore cast. Earlier concerns of convection around the
central Oregon terminals appears muted at this point based on
radar trends and weaker normalized CAPE values around RDM/BDN.
MVFR cat vsbys in smoke may develop around the BDN/PDT terminals
this evening, improve overnight and return Saturday morning.

&&

.FIRE WEATHER...Increased monsoonal moisture and instability across
the region will continue to bring an isolated to scattered
thunderstorm threat through Saturday. Abundant lightning and gusty
outflow wind threat will be across the WA Cascade east slopes and
eastern mountains today, then across the Blue Mountains and
Wallow County 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 /   0  30   0   0
ALW  60  89  62  91 /   0  30  10   0
PSC  57  91  57  93 /   0  20   0   0
YKM  59  90  60  92 /   0  10  10   0
HRI  59  90  59  92 /   0  30   0   0
ELN  56  85  58  86 /  10  20  10   0
RDM  50  85  49  87 /  20  10  10   0
LGD  55  87  54  89 /  20  60  20  30
GCD  55  88  54  91 /  20  20  10  10
DLS  64  90  62  92 /  10  10   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.
     Red Flag Warning until 9 PM PDT this evening for WAZ695.
     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 until 7 PM PDT this evening for ORZ694-695-
     697-699.
     Red Flag Warning from noon to 9 PM PDT Saturday for ORZ692>695-
     699.

&&

$$

DISCUSSION...82
AVIATION...90
FIRE WEATHER...82