387
FXUS66 KPDT 051151
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
451 AM PDT Wed Aug 5 2026

.KEY MESSAGES...

- Elevated to locally critical fire weather conditions will
  continue to persist through at least the better part of this
  week.

- Widespread moderate risk of heat expected to develop through
  the region by Thursday.

- Smoke and haze from local and regional wildland fires
  continue to suppress air quality levels through at least
  Thursday.

&&

.DISCUSSION...
Satellite & other night time products continue to show
widespread smoke and haze across the region from local and
regional wildland fires ignited over the past few weeks. Smoke
is expected to linger through at least Thursday (>90% chance) as
a ridge located offshore continues to move towards the region
through Thursday. This has allowed unhealthy levels of air
quality to accumulate, thus local agencies from Oregon &
Washington have issued Air Quality Alerts/Advisories for the
entire forecast area.

With the ridge axis expected to reach over the area in the
Thursday/Friday timeframe, we expect a warming trend to
continue until then with the NBM advertising chances of reaching
triple digits in parts of the Columbia Basin at around 30-50%.
Guidance is in very good agreement with HeatRisk values reaching
`moderate` with widespread chances of 80-100%. Isolated areas of
major HeatRisk is possible with 30-50% chances possible
Thursday & Friday in parts of the Yakima/Kittitas region. With
that being said, wildland fire smoke could inhibit the ridge
bringing its full potential of heat. Areas with thicker columns
of smoke may fall short several degrees than otherwise expected,
possibly tapering levels below major that would`ve reached it
otherwise. This brings issuing heat advisories at a low
confidence (10-30%) due too the difficult to forecast smoke
plumes in the area.

Guidance in the synoptic level through the weekend is in good
agreement that the pattern will turn into a zonal/quasi-zonal
flow with tighter pressure gradients, resulting in breezy to
locally windy conditions developing late this week. With dry air
lingering with minimum relative humidities still in the 10-18
percent range Friday and Saturday, chances of critical weather
conditions developing go up with 20-30% confidence. The main
factor in increased confidence will be how far and widespread
the winds will be. Although local areas are expected to be
critical, it`s not anticipated it will be a widespread event,
thus no fire weather highlights will be issued for the weekend
at this time.



&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Widespread smoke and haze from local and regional wildland fires
continue to impact all TAF sites through the next 24-hours.
Smoke plumes are large enough to bring at least MVFR and IFR
conditions at all sites, with persistance through the TAF
period. There`s a small chance (5 to 15 percent) of seeing smoke
levels temporarily improving to VFR with daytime heating mixing
smoke levels.

&&

.Preliminary Point Temps/PoPs...
PDT  93  58  97  62 /   0   0   0   0
ALW  94  63  98  68 /   0   0   0   0
PSC  95  59 100  61 /   0   0   0   0
YKM  94  62  98  63 /   0   0   0   0
HRI  95  60  99  64 /   0   0   0   0
ELN  92  61  96  63 /   0   0   0   0
RDM  96  53  99  55 /   0   0   0   0
LGD  96  58 100  61 /   0   0   0   0
GCD  98  58 101  60 /   0   0   0   0
DLS  97  64  99  64 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until 5 AM PDT Tuesday for WAZ024-026>030-
     521>523.
OR...Air Quality Alert until 5 AM PDT Tuesday for ORZ041-044-049-
     050-502-503-505>511.

&&

$$

DISCUSSION...95
AVIATION...95