864
FXUS66 KOTX 102342
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
442 PM PDT Fri Oct 10 2025

.KEY MESSAGES...

- Early winter storm for the northern mountains from the
  northern Washington Cascades to North Idaho Sunday into
  Monday morning.

- Gusty north to northeast winds on Monday.

- Below normal temperatures Sunday into early next week with
  highs in the 50s. Low temperatures dropping into the 20s and
  30s by Tuesday.

&&

.SYNOPSIS...
Cloud cover and precipitation chances expand across the region
tonight. The weekend brings breezy conditions, much cooler
temperatures, and continued precipitation with snow in the
mountains. Heavy snow with winter conditions in the northern mountains
above 3000 feet. Dry with temperatures warming to near normal
next week.

&&

.DISCUSSION...

...EARLY SEASON WINTER STORM TO BRING HEAVY SNOW TO THE
MOUNTAINS OF THE NORTHERN WASHINGTON CASCADES TO NORTH IDAHO...

Tonight through Saturday night: A deep low pressure system is
spinning off of the Oregon coast this afternoon. Good support
aloft ahead of the low with positive vorticity advection and
diffluence aloft will bring favorable dynamics. This along with
increasing moisture will result in widely scattered showers
primarily near the Cascade crest and then also over extreme
eastern Washington and in the Idaho Panhandle. Modest
instability at mid levels may result in a few embedded
thunderstorms. Otherwise, we are looking at mainly passing light
to moderate rain showers with this low as it ejects across
tonight. Winds will increase overnight into Saturday with breezy
conditions across the Columbia Basin and into the southern to
central Idaho Panhandle. Southwest winds will be particularly
gusty on Saturday across the Palouse with gusts up to between
20-30 mph expected. A shortwave disturbance pushing across in
the northwest flow for Saturday night will deliver another round
of primarily rain into the Idaho Panhandle. This next shot is
more likely to deliver wetting rains across the Idaho Panhandle
with between tenth and a quarter of an inch of rainfall
expected.

Sunday through Monday: Bigger impacts are anticipated with a
second upper level low that deepens across western Washington.
Models are in good agreement with a surface low spinning up over
northwest Washington Sunday afternoon and continuing to deepen
as it tracks down the western coastline. This will do two
things: (1) tighten the northerly pressure gradient with cold
Canadian air advancing into the region, and (2) draw moisture
northward across the region that overruns the advancing cold
air. Snow levels will start out fairly low at around 35000 feet
across the northern zones Sunday afternoon dropping to valley
bottom by Monday morning. Snow is expected to accumulate in
the northern mountains through the day Sunday. Warm road
temperatures may make it difficult for snow to accumulate
initially, but these temperatures are expected to drop
overnight Sunday. Strong dynamics and vertical lift in the snow
growth zone may also push snow levels down more so than models
are letting on. Snow will be heavy at times and I wouldn`t be
surprised if we see periods of an inch of snow per hour
particularly in the east slopes of the Cascades where easterly
flow produces favorable orographics. A big concern will be for
any backcountry recrationalists looking to camp in the
mountains over the weekend. Weather conditions will deteriorate
rapidly particularly late on Sunday. Expect winter conditions
and cold temperatures. Mountain passes will also see the
potential for snow covered roads and heavy at times for
Washington Pass and Sherman Pass; however, Loup Loup Pass,
Stevens Pass, and Blewett Pass will also see the potential for
snow travel. Below are the probabilities for snowfall thresholds
of at least 2", 4", and 8" and our mountain passes:

Mountain Pass    Chance of 2+"    Chance of 4+"     Chance of 8+"
Washington       95%              85%               70%
Sherman  95%      75%    25%
Lookout  35%   15% 0%
Stevens  60%   35% 15%
Blewett 25%  10% 0%
Loup Loup 70%  50%20%

A winter storm watch is in effect for Sunday through Monday
morning above 3000 feet across the northern zones. Heaviest snow
and best potential for impacts is expected Sunday afternoon
into Sunday night. /SVH

Monday Night through Thursday: A quieter pattern returns as the low
drops south over California and an upper ridge builds off the coast
provides a dry north to northwest flow over the Inland NW.  It will
feel like fall as low temperatures drop into the 20s and 30s for
most of the region, and daytime highs in the mid 50s to low 60s.
JW

&&

.AVIATION...
00Z TAFS: Moisture has increased ahead of the low late this
evening with mid level clouds and shower chances increasing.
Showers will increase primarily over the Cascade crest and over
extreme eastern Washington into the Idaho Panhandle through the
overnight hours. Westerly winds increase tonight and continue
into Saturday with gusts of 15-25 kts possible through Saturday
morning. Winds increase further into Saturday afternoon.
Increased boundary layer moisture will result in lowering
ceilings for KGEG-KSFF-KCOE-KPUW-KLWS. There is a 10-20% chance
of MVFR conditions with low stratus cover will be possible
across northeast Washington into the Idaho Panhandle for
Saturday morning.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
in VFR conditions today. Low confidence for MVFR conditions for
KPUW-KGEG-KSFF-KCOE overnight.

-----------------------
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        43  57  40  50  36  52 /  60  40  70  80  80  20
Coeur d`Alene  45  56  41  49  36  52 /  80  60  90  90  90  20
Pullman        41  55  38  47  38  54 /  60  60  90  80  80  30
Lewiston       50  62  46  55  43  60 /  60  60  80  80  70  20
Colville       34  57  29  50  29  51 /  60  70  70  80  90  30
Sandpoint      40  52  36  47  31  48 /  80  70 100  90  90  30
Kellogg        45  52  41  47  34  49 /  80  70 100 100  90  40
Moses Lake     42  62  39  54  40  54 /  20  30  20  60  70  50
Wenatchee      46  61  45  52  38  51 /  30  30  40  60  80  50
Omak           44  62  40  52  37  56 /  30  40  40  70  80  30

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Winter Storm Watch from Sunday morning through Monday morning
     for Northeast Mountains-Okanogan Highlands-Western
     Okanogan County.
     Air Quality Alert until noon PDT Monday for Central Chelan
     County-Okanogan Valley-Waterville Plateau-Wenatchee Area-
     Western Chelan County.
ID...Winter Storm Watch from Sunday morning through Monday morning
     for Northern Panhandle.

&&

$$