792
FXUS66 KPDT 062211
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
311 PM PDT Thu Aug 6 2026

.KEY MESSAGES...
- Elevated to critical fire weather conditions through the week
  due to periods of breezy conditions, low RH, and hot, dry, and
  unstable conditions. Red Flag Warnings in effect Friday
  morning through Saturday evening for wind and low relative
  humidity.

- Widespread smoke persists today, then westerly winds will
  likely (80% confidence) bring improvement Friday through the
  weekend, except in the vicinity of or downwind of ongoing
  wildfires.

- Widespread Moderate to locally Major HeatRisk today and
  Friday.

&&

.DISCUSSION...
Similar to the previous few days, satellite imagery shows
widespread smoke and haze across the forecast area this
afternoon. While some modest improvement in smoke has occurred
in central Oregon and south-central Washington, regional
wildfires continue to produce significant smoke which is now
being transported to the northeast.

Water vapor imagery reveals an upper-level ridge axis extending
from the Great Basin through the Pacific Northwest and into
British Columbia. Meanwhile, a low-pressure system is located
well offshore in the vicinity of 49N, 144W.

Under the ridge, hot temperatures will continue through Friday.
Widespread Moderate to locally Major HeatRisk is expected (80%
confidence) due to forecast afternoon temperatures in the 95-100
degree range and lows in the 50s and 60s (locally into the lower
70s). Wildfire smoke inhibits efficient solar heating so
afternoon temperatures may end up being several degrees cooler
than currently forecast where smoke is sufficiently dense; this
is most likely beneath the plumes from the Grasshopper Fire and
Rowe Creek Complex. Have opted to hold off on issuing any heat
headlines.

A couple shortwaves are likely (95% confidence) to flatten the
ridge Friday through the weekend, with the strongest expected
Saturday afternoon. This pattern will facilitate breezy to windy
westerly winds through the Cascade gaps and across the Blue
Mountain foothills and Columbia Basin. Wind coupled with low
relative humidity will lead to increasing fire weather concerns
and Red Flag Warnings have been issued (see FIRE WEATHER section
below). Breezy to windy westerly winds will be capable of
scouring much of the existing smoke from our forecast area;
while widespread improvement is anticipated (80% confidence),
smoke is still expected to be present downwind of ongoing
wildfires within their respective plumes, so some areas will see
continued smoke while others will be much clearer.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...MVFR or lower
conditions will prevail through most of the period. Smoke
from area wildfires will continue to impact all sites,
resulting in vsby down to IFR conditions and CIGs down to MVFR
conditions. Smoke is expected to worsen vsby conditions
overnight, especially at sites DLS/ALW/PDT. Winds at sites
RDM/BDN have helped to improve vsby, but vsby expected to
deteriorate to MVFR again once winds diminish tonight. Tomorrow,
increasing westerly winds through the Cascade gaps and Columbia
Basin is expected to help improve vsby at most sites. Sites
RDM/ALW may not improve until late tomorrow afternoon. Winds
will increase to 12-20kts with gusts up to 30kts at sites
DLS/PDT tomorrow afternoon, with winds less than 12kts at all
other sites tomorrow. Lawhorn/82

&&

.FIRE WEATHER...
Periods of elevated to critical fire weather conditions are
anticipated today into at least early next week due to a
combination of locally breezy winds and low relative humidity as
well as hot, dry, and unstable conditions.

Today through Friday, the combination of dry air and hot
temperatures will drive afternoon RHs into the single digits to
teens. Predominantly poor to fair overnight RH recovery is
forecast through the week, except for locally good to excellent
recovery in drainages. Of note, deep mixing across the region
coupled with locally breezy winds, especially central Oregon and
vicinity, may support plume-dominated fire this afternoon and
Friday. Have held off on issuing any zone-wide Red Flag
Warnings for hot, dry, and unstable conditions. Additionally,
high-resolution weather models (12Z HREF and 12Z REFS) continue
to highlight some potential (broadly 30-70% of members) overlap
of critical wind/RH thresholds in central and east-central
Oregon as well as the Cascade gaps of OR/WA this afternoon and
evening, but confidence was too low to issue any zone-wide Red
Flag Warnings.

Friday through Saturday, confidence is very high (95 percent)
in a return to breezy westerly winds through the Cascade gaps
and across the Columbia Basin as a couple weak shortwaves
flatten the ridge. The stronger shortwave appears
opportunistically timed Saturday afternoon to coincide with
afternoon heating to facilitate more widespread breezy winds.
Coupled with the dry air mass, forecast elevated to critical
fire weather conditions have prompted the issuance of multiple
Red Flag Warnings; confidence in the combination of critical
winds and relative humidity is high (80 percent) for Friday and
Saturday.

Looking ahead, persistent quasi-zonal flow or weak troughing
aloft will likely (80% confidence) keep breezy westerly gap
winds in place Sunday into at least early next week. Confidence
in meeting wind/RH criteria is low (20-50%) Sunday and Monday
for wind-prone areas.

&&

.Preliminary Point Temps/PoPs...
PDT  61  97  59  93 /   0   0   0   0
ALW  67  98  66  95 /   0   0   0   0
PSC  60  99  61  96 /   0   0   0   0
YKM  62  99  62  96 /   0   0   0   0
HRI  64  99  64  95 /   0   0   0   0
ELN  63  94  63  90 /   0   0   0   0
RDM  54  97  52  93 /   0   0   0   0
LGD  61 100  59  96 /   0   0   0   0
GCD  59 100  59  97 /   0   0   0   0
DLS  63  96  64  93 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Red Flag Warning from 11 AM Friday to 11 PM PDT Saturday for
     WAZ690-691.
     Air Quality Alert until 5 AM PDT Tuesday for WAZ024-026>030-
     521>523.
OR...Air Quality Alert until noon PDT Friday for ORZ041-044-049-050-
     502-503-505>511.
     Red Flag Warning from 11 AM Friday to 11 PM PDT Saturday for
     ORZ691-701-703.

&&

$$

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