863
FXUS66 KOTX 172051
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
151 PM PDT Mon Aug 17 2026

.KEY MESSAGES...

- Building high pressure will lead to diminishing mountain
  showers and thunderstorms.

- Warm, dry conditions for the midweek.

- Weekend system brings thunder threats and gusty winds
  increasing fire concerns.

&&

.SYNOPSIS...
Afternoon and evening mountain thunderstorm threat continues
for Monday with smaller area coverage. Temperatures trend
warmer. A drier airmass moves in by the middle of next week.
pattern change at the end of the week will bring cooler, breezy
conditions.

&&

.DISCUSSION...
Today through Wednesday: As high pressure builds over the PNW and
drier air moves in, temperatures will continue to be on the slight
uptick and minimum relative humidity will continue to decrease. This
will limit thunderstorm chances to only small mountain areas this
afternoon and evening. Lingering moisture in the far northern
Cascades and the Blue Mountains combined daytime heating will result
in a 5 to 10 percent chance of isolated thunderstorms. Main threats
with these thunderstorms include gusty outflow winds up to 30 mph,
lightning induced fire starts, and heavy downpours. These
chances decrease to 5 percent tomorrow.

Of more importance tomorrow is the increasing onshore flow combined
with a cross-Cascade pressure gradient that will bring breezy to
gusty winds to the Cascade gaps and lower Basin areas. With minimum
RHs in the low 20 percent range, the primary concern tomorrow will
be elevated fire weather conditions. Current projected wind gusts
are 15-20 mph with localized wind gusts up to 25 mph in some places.
These values and ranges are borderline for fire weather headlines,
but minor impacts still exist and precautions should still be taken
to avoid any new fire starts.

By Wednesday, winds will decrease and temperatures will remain in
the mid to high 80s. Due to increasingly dry conditions, there is
a near zero chance for precipitation from midweek on.

Thursday through Saturday: As the ridge stays in place over the
forecast area, temperatures increase on Thursday and Friday into the
low to mid 90s. This will result in Moderate HeatRisk across much of
eastern Washington on Thursday and Friday. Moderate HeatRisk impacts
all those sensitive to heat and do not have access to adequate
cooling and hydration, alongside beginning to impact some health
systems and industries.

On Friday, the low pressure system will begin moving eastward
towards the PNW coast. By Saturday, the upper level trough will move
through the state of Washington, ushering in a cold front. This cold
front will bring widespread gusty winds to the Inland Northwest.
There is at least a 30 percent chance and above for most of the
Basin, Waterville Plateau, and Palouse areas to see wind gusts 30
mph or higher. Those chances increase to 50% and above as you move
westward into the Waterville Plateau. Hot, Dry, Windy Index values
for this day are nearing the 90th percentile for most areas
mentioned above. Models are also showing increasing confidence
in thunderstorms ahead of the frontal passage. Nearly 75% of all
clusters support this pattern setup, indicating increasing
confidence in Saturday seeing elevated to critical fire weather
conditions. /AS

&&

.AVIATION...
18Z TAFs: Mostly VFR conditions will prevail through the 24
hour TAF period with isolated MVFR vis/cigs due to smoke.
Confidence in visibility impacts is too low at this time to
bring TAF visibilities lower than 6SM for all terminals apart
from EAT. Smoke models keep EAT at MVFR for portions of the TAF
period from the Little Giant Fire. As onshore flow increases,
winds will increase tomorrow. EAT will begin gusting to 15-20kts
around 05Z tomorrow, which should help disperse smoke and
improve air quality. Later on in the TAF period, PUW (12Z),
GEG (15Z), and SFF (15Z) will follow suit with increases to
wind. COE, LWS, and MWH will see increases in wind at the start
of the next TAF period.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate
confidence in MVFR for EAT due to smoke. Moderate confidence in
timing of wind increases. When smoke will begin decreasing in
EAT is dependent on when wind increases happen - this is the
highest impact alternate scenario, and amendments will be needed
should timing differ. /AS


-----------------------

Confidence descriptors:

Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance

For additional probabilistic information for NWS Spokane airports,

please refer to the Aviation Dashboard on our webpage:
https:/www.weather.gov/otx/avndashboard

&&

.Preliminary Point Temps/PoPs...
Spokane        59  89  58  88  56  92 /   0   0   0   0   0   0
Coeur d`Alene  59  88  56  87  56  91 /   0   0   0   0   0   0
Pullman        53  86  49  86  49  92 /   0   0   0   0   0   0
Lewiston       65  94  61  93  62  96 /   0   0   0   0   0   0
Colville       51  89  49  87  48  91 /   0   0   0   0   0   0
Sandpoint      54  85  52  84  52  88 /   0   0   0   0   0   0
Kellogg        56  84  54  84  55  90 /   0   0   0   0   0   0
Moses Lake     57  91  55  89  55  92 /   0   0   0   0   0   0
Wenatchee      66  91  64  89  65  92 /   0   0   0   0   0   0
Omak           64  92  60  90  61  93 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until 10 AM PDT Friday for Central Chelan
     County-Moses Lake Area-Okanogan Highlands-Okanogan Valley-
     Upper Columbia Basin-Waterville Plateau-Wenatchee Area-
     Western Chelan County-Western Okanogan County.
ID...None.

&&

$$