164
FXUS66 KOTX 210832
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
132 AM PDT Mon Sep 21 2026

.KEY MESSAGES...

- Warm temperatures through Tuesday with afternoon highs in the
  high 70s to mid 80s.

- Temperatures begin cooling midweek, with an increasing risk
  for showers and high elevation snow Friday into Saturday.

- Breezy Tuesday into Wednesday. Potential for stronger winds
  Friday with a cold front passage.

&&

.SYNOPSIS...
Expect warm and dry conditions through Tuesday, with high
temperatures in the high 70s to mid 80s. Wednesday through
Friday will see temperatures cool to around normal and breezy
afternoons. A stronger cold frontal passage on Friday will
result in gusty winds, chances for showers, and high elevation
snow.

&&

.DISCUSSION...
Monday-Tuesday: The upper-level ridge will begin to slowly
flatten today and Tuesday as a broad upper-level crosses over
130W and shortwaves begin ejecting into British Columbia. Bands
of high clouds will pass through the region at times over the
next few days but conditions will remain dry. Monday will remain
mild with temperatures within 1-2 degrees of Sunday then cool
5-10 degrees heading into Tuesday with the arrival of a weak
cool front. Winds for much of the region will remain light
today. There will be a noticeable increase in afternoon and
evening breezes across the Okanogan Valley and through the
Cascade river valleys starting off from the south/southeast then
shifting to the west and northwest in the evening. Winds for
Tuesday will become a bit more breezy region-wide as cooler air
begins to bleed into the region. West to southwest winds will
increase closer to 10-15 mph with gusts 20-25 mph and locally
stronger through the windier Cascade gaps.

Wednesday-weekend: A broad upper-level trough will become
established over the Eastern Pacific and Northwest by Wednesday
with temperatures cooling further and residual breeziness. A
reinforcing shot of cooler air and shortwave dropping into the
offshore trough on Thursday will dig into the base of the trough
allowing flow to buckle slightly over the Inland NW. This has
potential to warm temperatures another 1-5 degrees from
Wednesday but largely unrealized in Central WA and most
noticeable in far southeastern WA and the lower Idaho Panhandle
including the L-C Valley where highs will rebound closer to 80F.

Confidence continues to increase for a more robust trough and
cold front Friday. There remains considerable timing differences
still varying from Thursday night to Friday afternoon dialing
int the frontal passage timing. Confidence is high for increased
winds with this system due to a 8C cooling of the air mass but
impacts and precise speeds will heavily depend on if this front
passes through during peak heating or overnight as well as how
quickly the system passes through. A scenario with a slower
passage and overnight would deliver the lighter side of the wind
outcomes with gusts mainly 15-25 mph. A scenario with an
afternoon passage and swift progression of the front would be a
windy outcome with gusts 25-35 mph and local gusts around 40
mph. The latest probabilities from the NBM come with a 60-80%
chance for wind gusts at least 20 mph, 20-50% for 30 mph, and
10-15% chance for 40 mph. The windier solution would also
suggest sustained winds of 15-25 mph for our windier areas from
the East Slopes to the Palouse. This is something we will need
to monitor closely in the coming days.

The system will also deliver cooler temperatures with highs
cooling from the 70s Wednesday and Thursday then into the 60s
Friday into the weekend. Some mountain valleys may be flirting
with freezing over temperatures heading into the weekend.

As for precipitation, ensembles are indicating a 50-60% chance
for at least 0.10" along the Cascade Crest and mountains of NE
WA and N ID. The potential outcomes for these areas are as high
as 0.50 inches or more. This could equate to several inches of
snow for some of the highest peaks. Confidence is much lower for
rainfall amounts outside of these areas and will depend on the
speed of the trough Friday-Saturday. There has been an increase
in probabilities for at least some rainfall region- wide and
this seems logical given the strong forcing expected along this
frontal boundary. Additional precipitation chances could come in
the post frontal air mass with convective showers under the
cool pool. Latest guidance has increased the chance for a tenth
of rain toward 20-40% for locations like Lewiston, Pullman,
Spokane, Kellogg, Colville, and Omak. Outlooks are not as
favorable in the lee of the Cascades with probabilities less
than 20% for locations like Ephrata and Moses Lake. Wenatchee
and Chelan are closer to 20%. There is a slight chance for
isolated thunderstorms Friday with the frontal passage but this
comes with very low confidence.

Snow levels in the Cascades will dip toward 6500 feet Friday
and 5500 feet Friday night into Saturday morning. Those
venturing into the high country should be prepared for cooler
temperatures and wet conditions. At this time, snow
accumulations look light but a few of the highest peaks near the
immediate Cascade crest could pick up several inches. /sb

&&

.AVIATION...
12Z TAFS: VFR conditions are expected through the forecast
period. Mostly clear, but increasing and thickening high
clouds from the west this afternoon into tonight. Winds
generally less than 10kts, except some winds up 15kts near KPUW
15-18Z.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
in VFR conditions. /Solveig

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

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        84  53  77  49  72  48 /   0   0   0   0   0   0
Coeur d`Alene  82  53  76  49  71  48 /   0   0   0   0   0   0
Pullman        82  50  74  45  70  45 /   0   0   0   0   0   0
Lewiston       86  57  81  52  76  53 /   0   0   0   0   0   0
Colville       82  46  79  42  73  42 /   0   0   0   0   0   0
Sandpoint      78  49  74  46  70  45 /   0   0   0   0   0   0
Kellogg        81  52  75  48  70  49 /   0   0   0   0   0   0
Moses Lake     84  51  79  46  73  48 /   0   0   0   0   0   0
Wenatchee      83  56  77  51  72  53 /   0   0   0   0   0   0
Omak           83  52  79  47  73  48 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...None.
ID...None.

&&

$$