198
FXUS66 KOTX 280758
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1258 AM PDT Sun Sep 28 2025

.KEY MESSAGES...

- Warm and dry today.

- Areas of haze and smoke impacting air quality across the
  region.

- Unsettled weather pattern next week with multiple chances for
  showers and a few thunderstorms.

&&

.SYNOPSIS...
Temperatures top out in the 70s to 80s today except. A pattern
change commences Monday and continues through the week.
Temperatures will be cooling closer to normal with an increasing
risk for showers.

&&

.DISCUSSION...
Sunday: Heights rise over the region ahead of an approaching trough.
This will equate to a warming trend to close out the weekend
under mostly sunny skies once bands of high clouds clear north
of the International border. Winds will be steady from the south
with speeds up to 10 mph. Temperatures will rebound into the
upper 70s to lower 80s. The exception will be in the East Slopes
where inversions will be more persistent and keep smoke
lingering through the day keeping temperatures as much as 10
degrees cooler than the air mass would support otherwise.

Monday-Friday: An eastward extension of the aforementioned trough
will begin to swing inland Monday with increasing clouds but
little in the way of appreciable precipitation. Elevated
instability over Idaho and far E WA will bring a 20-30% chance
for light showers with rainfall amounts generally less than a
tenth. Moderate rains will move into W WA and toward the Cascade
Crest with a few light showers possibly extending into the East
Slopes. The atmosphere will continue to moisten Monday night
into Tuesday with spotty showers increasing over the region.
Rainfall amounts under the showers will increase closer to a
tenth with localized bands capable of a quarter of an inch.
Moderate southerly flow in the midlevels will result in
localized downsloping in the lee of east-west ridgelines.
Unfortunately, this typically impacts locations like Wenatchee
and vicinity coming off Mission Ridge and may have impacts for
some fires in the East Slopes including the Lower Sugarloaf.
While this is ongoing, a robust low dropping out of the Gulf of
AK will reinforce the longwave trough and slowly wobble toward
into the Pac NW going through the middle to end of the week.
This low will fill and weaken while coming inland but the
Wednesday-Thursday time-frame looks to deliver some of the
highest chances for precipitation region-wide with increased
ascent from a combination of diffluent flow with the midlevels
and left exit region jet dynamics. Overall, it is safe to say
that we are going to experience our first fall-like system
knocking temperatures back closer to normal through the week and
bringing several opportunities for rainfall. There will be
enough instability Monday night through Thursday in which some
cells may deepen enough to produce a few lightning strikes.
These cells would also be capable of heavier downpours and
erratic wind gusts up to 30 mph. Not your typical, dry subcloud
layer wind gust, more of stronger winds mixing down with
downdrafts.

On that note, winds will become breezy on Monday and Tuesday with
a general southerly direction. Winds of 10-15 mph with stronger
gusts are expected within the Okanogan Valley and Western Basin
and locally in the foothills of the Blue Mountains.

The exact details of the evolution of the low late week into the
weekend comes with moderate uncertainty with several different
scenarios playing out from the low breaking off and drifting
into the Great Basin and weak ridging over the Inland NW to
another trough coming in on its heels, kicking its remnants east
and dropping into the region with another shot of cooler air
and precipitation. This later solution seems to have more of the
100 member ensemble suite leaning in this direction but not
many with a 60/40 split. Now that we have entered the transition
season of autumn and models project energy moving through the
upper-latitudes, I expect modest uncertainty and daily changes
with these details from run to run.

The good news from the pattern change is the return of
precipitation chances for our ongoing fires, cooler temperatures,
and generally higher - fall like humidity values. This is a
good sign that we may have finally turned the corner on this
fire season!

To update the probabilities for at least 0.25" from 5AM Monday
through 5AM Thursday given in the previous forecast discussion:

Columbia Basin: 10-30%  - No change
Palouse: 30-70%  - Slight decrease for western reaches of the Palouse
Spokane area: 50%  - No change
Okanogan and Methow Valleys: 60-70% - Slight increase
Northern Mountains: 60-90%  - No change
ID Panhandle: 70-90% - No change
East Slopes: 20-30% Wenatchee to Entiat, 30-60% Lower Sugarloaf,
60-70% Labor Mountain, and 90% close the Cascade crest

/sb

&&

.AVIATION...
06Z TAFS: VFR conditions continue through the period with areas
of haze and smoke. Main concern for restrictions to vis will be
Wenatchee, Chelan, Omak, and into the East Slopes including
Winthrop, Plain, and Lake Wenatchee. Smoke did not clear out of
these valleys today due to poor mixing and persistent inversions
but fires burned actively above the inversions continuing to
produce heavy smoke. Winds tomorrow will remain light with a
light southeast component leading to similar or worsening
conditions for these same areas.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Low confidence for MVFR or worse conditions from wildfire smoke
at any terminals outside the East Slopes of the Cascades but at
times, sites have reported 6SM so would not rule it out. /sb

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

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:/weather.gov/otx/avndashboard

&&

.Preliminary Point Temps/PoPs...
Spokane        83  53  75  54  70  50 /   0   0  10  60  50  40
Coeur d`Alene  84  53  77  54  68  49 /   0   0  10  60  60  40
Pullman        81  51  73  50  68  47 /   0  10  10  60  60  30
Lewiston       85  58  79  59  74  55 /   0  10  10  70  50  30
Colville       79  43  74  43  67  39 /   0  10  20  60  80  60
Sandpoint      79  48  73  49  65  45 /   0   0  20  60  80  60
Kellogg        83  58  75  56  65  52 /   0   0  20  70  80  50
Moses Lake     82  52  75  52  72  50 /   0  10  10  50  40  40
Wenatchee      76  59  75  55  70  53 /   0  10  20  60  50  50
Omak           79  53  75  53  70  50 /   0  10  20  60  60  50

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until noon PDT Monday for Central Chelan
     County-Okanogan Valley-Waterville Plateau-Wenatchee Area-
     Western Chelan County.
ID...None.

&&

$$