599
FXUS66 KOTX 082334
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
334 PM PST Mon Dec 8 2025

.KEY MESSAGES...

- Strong west to southwest winds tonight into early Tuesday
  morning may result in downed trees and power outages.

- 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. Widespread strong wind gusts are expected Monday
night into Tuesday which may result in downed trees and power
outages.

&&

.DISCUSSION...

...STRONG LONG DURATION ATMOSPHERIC RIVER EVENT TO BRING POTENTIAL
FOR FLOODING, ROCK/MUD SLIDES THROUGH THURSDAY, AS WELL AS GUSTY
WINDS TONIGHT...

Tonight through Thursday: The first wave of two separate AR events
is ongoing today. A warm front has pushed through Eastern Washington
and now into the Idaho Panhandle at 2:30 pm this afternoon.
Precipitaiton intensity over much of the region has been light
to moderate with heavier intensity being observed closer to the
Cascade crest. Much of the precipitaiton for tonight will
largely remain now at the Cascade crest and in the Idaho
Panhandle. The Cascade crest will see an additional 1.5 to 3.0
inches and the Idaho Panhandle up to an additional quarter plus
inches of precipitation. The higher terrain of the Panhandle
will more likely see upwards of an additional half of an inch
with mountains more likely to receive an additional inch or so.
The main concern with the precipitation tonight that will
largely fall as rain over the Cascades will be for 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 will remain in effect for
Chelan County and we have actually extended this flood watch to
include the next round of precipitation Tuesday through
Thursday as well.

A potentially more impactful hazard will be winds mixing down later
this evening and overnight. Model guidance is in good agreement with
strong winds aloft with 50-60 mph winds up around 2,000 feet above
ground level. Where the uncertainty comes is how effectively will we
be able to mix down these winds in the warm sector. Typically this
is difficult to do to its fullest potential. The surface gradient
isn`t necessarily significant to the point of what we would
expect to achieve high wind criteria (sustained speeds of 40+
mph and/or gusts 58+ mph). The GEFS is on the higher end when
compared to the ECMWF Ensemble members. The GEFS is progged to
have a MSLP of near 16 mb between Portland, OR and Glacier, MT,
whereas the ECMWF ensemble mean is more around 12 mb. There is
uncertainty with the potential for how strong winds may
actually get. The HREF mean wind guidance is in line with what
our forecast has been portraying with sustained winds in the
25-35 mph range across the Columbia Basin and gusts up to 50-55
mph. This is in the high end range for a wind advisory. It`s
entirely possible, if not probable, that we will see isolated
spots that meet high wind criteria. An additional factor to
consider is soils being fairly saturated and this may lead to
more downed trees than what we typically would expect with winds
of this magnitude.

By Tuesday, we see the next AR move into the region, and this one
will be similar in magnitude as today`s and also be a bit longer in
duration on the order of 36-48 hours. The peak of the AR event will
be the first 24 hours Tuesday night through Wednesday, and then see
precipitation rates come down a bit for the latter half Wednesday
night into Thursday. However, this next round coming on the heels of
a healthy amount of rain over the Cascades and Idaho Panhandle will
be one to watch for hydrology related impacts. An area of concern in
addition to Chelan county will be the headwaters across the Central
Panhandle Mountains and drainages downstream. This includes the
Coeur d`Alene River, St. Joe River, and, to a lesser extent,
Paradise Creek. Rainfall with this next AR will range from around an
inch to as much as 3+ inches in the Idaho Panhandle with heaviest
amounts being across the Central Panhandle Mountains. Additional
rainfall in combination with snowmelt is expected to result in
rapid rises to rivers, small streams, and creeks. Minor flooding
is forecast along the Coeur d`Alene River, and I wouldn`t be
surprised if the St. Joe River sees flooding impacts as well. A
Flood Watch is in effect for Tuesday through Thursday. If you`re
in a low lying area, or along a stretch of the river, small
stream, or creek take precautions to protect property for the
potential of flooding. Steep terrain will also be prone to
mud/rock slides as well. This second AR will continue to pound
the Cascades with additional rain as well. We will have a good
idea of how burn scars responded to the first round of rain
tomorrow. Those traveling along Highway 97 over Blewett Pass
should be advised that there may be some debris that comes out
on the road with several days of soaking rain on the Labor
Mountain burn scar.

These AR events will mainly bring impacts due to rain and melting
snow, but the cold front passage tonight will see snow levels lower
that light snow will accumulate over Stevens Pass and Lookout Pass.
Accumulations will be in the neighborhood of 1-3 inches. That will
be the case at Stevens Pass on the back edge of the cold front
tonight and then also a couple of inches or so expected as snow
transitions back to rain with the second AR event.

Thursday night through Monday: Weather turns more benign at the end
of the week as a high pressure ridge builds over the eastern
Pacific. The ridge looks transitory though and model guidance does
indicate a frontal system pushing across over the weekend. However,
the ridge will give a reprieve to the wet weather on Friday at
least and allow levels on rivers and streams to decrease.
Precipitation over the weekend won`t be nearly of the scale as
over the next few days. Temperatures remain mild with any snow
remaining over the mountains. /SVH

&&

.AVIATION...
18Z TAFs: A slug of moisture moving into the Northwest will bring
widespread rainfall to airports across the Inland Northwest today.
The region will be within the warm sector through the afternoon, and
this tends to keep ceilings up a bit with predominantly MVFR
conditions anticipated. Rain intensity will be moderate at
times though through this afternoon across northeast WA into the
Idaho Panhandle and this will reduce surface visibility to
between 3-6 SM with brief IFR conditions at times for
KGEG/KSFF/KCOE/KPUW. Then the winds become more of a factor for
this evening and overnight. A warm front will push through
eastern Washington by 00-02Z with precip decreasing. The region
will still be within the warm sector between 00-09Z before we
see the cold front sweep across between 09-13Z. Winds within the
warm sector will be south to southwest with low level wind
shear and/or gusty at times up to 30-35 kts at the surface. Top
of the mixed layer will see westerly winds up to 45-50 kts up to
2 kft agl. Cold front passage will then see those stronger
winds mix down to the surface.

.FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for
MVFR conditions at KGEG/KSFF/KCOE/KPUW with precipitation today and
a 30-50% chance for IFR conditions (most likely occurring with
moderate rainfall). High confidence for wind gusts greater than 40
kts from the southwest from Pullman to Spokane (KPUW/KGEG/KSFF/KCOE)
after 00Z and moderate confidence that wind gusts will increase to
around 50 kts between 05-12Z. /SVH

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

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        42  49  39  53  45  51 /  70  30 100  80  70  60
Coeur d`Alene  42  47  38  51  45  49 /  90  40 100  90  80  70
Pullman        44  49  41  54  47  52 /  90  80 100  90  80  80
Lewiston       50  55  46  60  54  57 /  80  80 100  80  70  60
Colville       35  45  32  47  35  46 /  60  10 100  70  60  50
Sandpoint      39  45  35  46  41  46 / 100  30 100 100  80  70
Kellogg        40  46  38  50  46  49 / 100  80 100 100  90  90
Moses Lake     42  49  41  57  44  55 /  40  50  90  50  40  40
Wenatchee      40  47  41  54  43  52 /  80  50 100  70  60  60
Omak           35  44  36  48  36  46 /  70  10 100  60  50  40

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from 7 PM this evening to 7 AM PST Tuesday for
     Lower Garfield and Asotin Counties-Northeast Mountains-
     Spokane Area-Upper Columbia Basin-Washington Palouse.
     Flood Watch through Thursday afternoon for Central Chelan
     County-Wenatchee Area-Western Chelan County.
ID...Flood Watch through Thursday afternoon for Central Panhandle
     Mountains-Coeur d`Alene Area-Idaho Palouse-Northern
     Panhandle.
     Wind Advisory from 7 PM this evening to 7 AM PST Tuesday for
     Central Panhandle Mountains-Coeur d`Alene Area-Idaho
     Palouse-Lewiston Area-Northern Panhandle.

&&

$$