508
FXUS66 KPDT 170538
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1038 PM PDT Thu Jul 16 2026

.Updated Aviation Discussion.


.KEY MESSAGES...
- Isolated thunderstorms over the Blue Mountains and their
  adjoining foothills this afternoon and evening. The
  environment is supportive of isolated strong to severe storms,
  capable of producing gusty outflow winds and hail.

- Breezy to windy this afternoon and evening, then breezy
  Friday.

- Predominantly above-normal temperatures likely (50-80%
  confidence) to persist through next week.

&&

.DISCUSSION...
Water vapor imagery shows a deep closed low churning offshore
in the vicinity of 45.6N, 126.5W this afternoon. Meanwhile, a
broad ridge of high pressure is located over the western CONUS,
leading to southerly to southwesterly winds aloft over the
forecast area. Monsoonal moisture from the Southwest is still
present over the region with RAP-based Mesoanalysis suggesting
PWATs of 1-1.2" over the Blue Mountains and their adjoining
foothills. Coupled with ample surface moisture (dew points in
the upper 40s to lower 60s from surface observations),
sufficiently steep mid-level (700-500 mb) lapse rates of 7-8
C/km, and modest synoptic-scale forcing associated with the
upper low, the environment is primed for additional shower and
thunderstorm development through the evening. The northern Blue
Mountains, their foothills, and Wallowa County are under a
Marginal risk of severe thunderstorms per SPC`s latest forecast,
with the main hazards being severe outflow wind in excess of 50
kts and hail up to 1" in diameter. DCAPE 1300-1500 J/kg is
strongly supportive of gusty outflow winds with any stronger
convection that develops.

A strong cross-Cascade temperature gradient (25-30 degrees),
marine layer on the west side, and cross-Cascade pressure
gradient should support widespread breezy to windy westerly to
northwesterly winds through the Cascade gaps and into the
western portion of the Columbia Basin through the evening and
into the overnight period. Have issued wind advisories for
the aforementioned area through 08Z tonight.

Looking ahead, confidence is very high (95%) that the upper low
will lift northeast into British Columbia through tomorrow and
into the weekend. Breezy winds will continue through the Cascade
gaps each day, and lower RH on Friday may lead to localized
overlap of critical wind/RH (see Fire Weather discussion below).

Heading into next week, there is still uncertainty in details of
the 500-hPa pattern, but confidence is medium-high (50-80%) in
predominantly above-normal temperatures across the forecast
area as the region remains under the influence of a broad ridge
of high pressure over the western CONUS.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
VFR conditions at most sites, with the exception of MVFR at KPDT
and IFR at KALW due to reduced visibilities related to smoke
from nearby wildfires. These conditions are expected to persist
overnight, improving by mid-to late morning. Due to the building
ridge and strengthening high pressure, sub-VFR conditions are
still expected through the day before degrading again Friday
evening and overnight. Breezy winds of 15-25kts are likely for
KDLS/KPDT/KRDM/KBDN through the afternoon, subsiding through the
evening. 75

&&

.FIRE WEATHER...
Isolated thunderstorms are expected to continue through this
evening, mainly over the Blue Mountains. Stronger thunderstorms
will be capable of producing strong, gusty, and erratic outflow
winds in excess of 60 mph.

Tonight into early Friday, there is a very low chance (15% or
less) of additional high-based showers and isolated
thunderstorms over the Blue Mountains and eastern half of the
Columbia Basin.

Breezy to windy westerly to northwesterly winds of 15-30 mph
with gusts of 25-45 mph will persist through the Columbia Gorge
and into the Basin through early Friday, but RH should remain
above critical values so no Red Flag Warnings have been issued.

Warm, dry, and locally breezy conditions are then forecast
Friday through the weekend with very low chances (15% or less)
of showers or thunderstorms. Portions of the eastern Columbia
River Gorge and western half of the lower Columbia Basin of
Oregon may (50% confidence) flirt with overlap of critical
wind/RH Friday afternoon and evening.

&&

.Preliminary Point Temps/PoPs...
PDT  56  90  57  91 /  10   0   0   0
ALW  63  93  63  93 /  10   0   0   0
PSC  61  95  61  95 /  10   0   0   0
YKM  59  94  58  94 /   0   0   0   0
HRI  59  93  61  94 /   0   0   0   0
ELN  56  88  56  86 /   0   0   0   0
RDM  46  89  50  91 /   0   0   0   0
LGD  58  94  57  93 /  20   0   0   0
GCD  54  96  54  95 /   0   0   0   0
DLS  58  87  60  90 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory until 1 AM PDT Friday for WAZ024-026.
OR...Wind Advisory until 1 AM PDT Friday for ORZ041-044-510.

&&

$$

DISCUSSION...86
AVIATION...75
FIRE WEATHER...86