848
FXUS66 KPDT 181200
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
500 AM PDT Sat Jul 18 2026

.KEY MESSAGES...

- Critical fire weather conditions continue through the Columbia
  Basin of Oregon through 10 PM tonight due to breezy winds and
  low relative humidities.

- Widespread moderate/major HeatRisk developing through early
  next week.

- Elevated fire weather conditions persist through the next
  several days with low relative humidities and diurnal breezy
  winds developing.

&&

.DISCUSSION...
A mid/upper level short wave is present in British Columbia,
allowing breezy winds to develop over the next few days. Dry air
across the region will persist and, with tandem to the earlier
mentioned breezy winds, bring elevated fire weather conditions
through at least the next few days with critical fire weather
conditions developing through 10 PM tonight in the Columbia
Basin in Oregon.

Guidance and cluster analysis is in great agreement (70-90%
chance) that the shortwave will exit the region in the Monday
time frame and the ridge that is currently situated over the
Great Plains will dominant the weather pattern and allow a
warming trend to begin and persist through mid-next week. This
looks to probably be the biggest heat wave so far this year with
NBM advertising 50-80% chances of high temperatures exceeding
100 degrees Tuesday in the populated areas in the Columbia Basin
& Yakima Valley. Chances slightly decrease Wednesday, but
considerably drop down to 30-50% on Thursday. Looking at
HeatRisk chances, widespread moderate chances develop with
80-100% chances Tuesday through Thursday, with major chances of
HeatRisk at 40-70%. Will need to monitor over the next few days,
but it`s becoming likely that heat highlights may be warranted
if trends continue as they are.

The pattern is likely (50-70% chance) that it will become
cooler and wetter going into the second part of next week with a
mid/upper level low pushing through the PacNW and a tropical
storm in the Pacific just off Mexico influencing the moisture
transportation into the region. Chances of showers (20-40%
chance) develop across the Blue Mountains mid-week with the
greatest chance occurring Thursday.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
VFR conditions prevail across all sites. Currently forecasted to
prevail, however smoke from local wildfires may drop
visibilities for the Columbia Basin/Central Oregon sites to MVFR
to IFR levels temporary. Otherwise, clear conditions will pave
way for no CIG issues.&&

.Preliminary Point Temps/PoPs...
PDT  91  56  91  61 /   0   0   0   0
ALW  93  62  93  64 /   0   0   0   0
PSC  95  59  94  61 /   0   0   0   0
YKM  92  58  94  63 /   0   0   0   0
HRI  93  60  94  63 /   0   0   0   0
ELN  84  56  91  59 /   0   0   0   0
RDM  91  51  93  59 /   0   0   0   0
LGD  94  56  94  59 /   0   0   0   0
GCD  96  55  96  60 /   0   0   0   0
DLS  89  61  95  65 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...None.
OR...Red Flag Warning until 10 PM PDT this evening for ORZ691.
     Air Quality Alert until noon PDT Monday for ORZ050-502-503-505-
     506-508.

&&

$$

DISCUSSION...95
AVIATION...95