258
FXUS66 KOTX 091221
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
421 AM PST Tue Dec 9 2025

.KEY MESSAGES...

- Decreasing winds Tuesday morning.

- Heavy mountain rain will bring a risk for flooding in the
  Cascades and the Idaho Panhandle, especially in steep areas
  and near burn scars.

&&

.SYNOPSIS...
An active weather pattern will impact the area through the week.
A series of warm and wet weather systems will result in periods
of heavy mountain rain, lowland rain, high mountain snow, and
gusty winds.

&&

.DISCUSSION...
...STRONG ATMOSPHERIC RIVER RIVER EVENT RETURNS TONIGHT THROUGH
THURSDAY BRINGING POTENTIAL FOR FLOODING, AS WELL AS ROCK AND MUD
SLIDES IN THE CASCADES AND IDAHO PANHANDLE...

Today: The Atmospheric River responsible for the steady rains and
windy conditions over the past 24 hours will slide south into
Oregon today, before lifting back north over the region. This will
allow conditions to dry out, along with a rapid decrease in winds
between the early to late morning hours as pressure gradients
relax. Significant rains over the past 24 hours along with snow
melt in the Cascades and ID Panhandle will lead to continue rises
on area rivers, while small streams are likely to fall with the
break in the rain.

Tuesday Night through Thursday: The next atmospheric river lifts
north as precipitable water values increase to 250-300% of normal.
An initial warm front will help produce widespread precipitation
initially for Tuesday Night. But after the front passes, rain is
expected to become mainly focused again over the Cascades and ID
Panhandle for Wednesday and Thursday as strong downslope for off
the Cascades dominates across most of Central and Eastern
Washington.

Snow levels at the onset will range from 3500-4500 feet allowing
for mountain snow to initially fall Tuesday evening with 2-4
inches of wet snow over the mountain passes including Stevens,
Loup Loup, and Sherman. Lighter amounts up to 2 inches are
possible for Lookout Pass. Snow levels rapidly rise to 7000-9000
feet by Wednesday morning.

The atmospheric river remains nearly stationary Wednesday into
Thursday, aimed at the Central and Northern Cascades into the ID
Panhandle producing heavy rain. The ECMWF, GFS, and Canadian
Ensembles are producing another 3-6 inches of rain in Western
Chelan county, with up to 6-10 inches along the Cascade crest. For
the ID Panhandle 1-4 inches is forecast. This combined with snow
melt will lead to sharp rises on rivers and streams. In the
Cascades river rises will be monitored closely for the Stehekin,
Wenatchee, and Entiat Rivers as well as the small streams. For the
ID Panhandle the St Joe and Coeur d`Alene Rivers are the main
concern as well as small streams. Another concern for the Cascades
will be rock/mud slides, especially so in steep terrain and near
newer burn scars including the Pioneer above Stehekin, Sugarloaf,
and Labor Mountain burn scars. A flood watch remains in effect
through Thursday afternoon for Chelan, Benewah, Kootenai, and
Shoshone counties.

Another story will be the abnormally warm temperatures. The next
atmospheric river brings an increase in southwest winds, with very
mild 850mb temperatures of 5-9C. This may allow high temperatures
to reach the mid 50s to mid 60s over much of the Columbia Basin,
and down into the LC Valley, which would be near records for
Wednesday. And Wednesday Night lows will only drop into the upper
30s and 40s, except mid 50s for the LC Valley. These temperatures
are as much as 20 to 25 degrees above normal.

Thursday Night through Monday: The atmospheric river lifts norths
and weakens heading into Friday but enough moisture and upslope
flow lingers in the Cascades and ID Panhandle for more
precipitation but with decreasing intensity. Snow levels also come
down a bit, but still high around 4000-6000 feet. On Sunday into
Monday ensembles show another round of precipitation moving in as
moist precipitable water plume around 175-200% of normal takes
aim at the area from southwest to northeast. This is likely to
be another mild system with rain and high mountain snow, but
amounts looks much less compared to those this week. JW


&&

.AVIATION...
12Z TAFs: Winds will decline through the morning. An
atmospheric river is bringing showers to the KPUW through 14z
before shifting south. There has been enough downslope flow off
the Cascades to dry out the boundary layer, with VFR conditions
favored for the majority of Central and Eastern Washington
through the day on Tuesday. But then another round of rain moves
in Tuesday evening as the atmospheric river lifts north again,
with widespread CIGS of MVFR expected to develop, locally to
IFR.

.FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate to
High confidence on VFR conditons through Tuesday. Moderate
confidence on the IFR-MVFR reforming overnight. Low confidence
on the timing of occurring. JDC

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

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        49  39  53  47  52  42 /  10 100  60  70  60  30
Coeur d`Alene  48  38  53  47  51  42 /  20 100  90  90  80  50
Pullman        50  40  55  49  52  46 /  70 100  70  60  80  50
Lewiston       56  46  62  54  60  50 /  70 100  40  50  60  40
Colville       48  32  47  37  47  32 /  10 100  50  70  60  30
Sandpoint      47  34  48  44  48  37 /  30 100  90  90  90  50
Kellogg        49  37  51  47  49  44 /  80 100 100  90  90  70
Moses Lake     52  40  58  47  56  40 /  30  90  20  40  40  10
Wenatchee      49  39  55  45  52  43 /  30 100  60  70  60  20
Omak           47  36  47  38  47  35 /  10 100  40  60  50  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch through Thursday afternoon for Central Chelan
     County-Wenatchee Area-Western Chelan County.

     Wind Advisory until 7 AM PST this morning for Lower Garfield
     and Asotin Counties-Northeast Mountains-Spokane Area-
     Upper Columbia Basin-Washington Palouse.

ID...Flood Watch through Thursday afternoon for Central Panhandle
     Mountains-Coeur d`Alene Area-Idaho Palouse-Northern
     Panhandle.

     Wind Advisory until 7 AM PST this morning for Central
     Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse-
     Lewiston Area-Northern Panhandle.

&&

$$