FXUS66 KOTX 111137

Area Forecast Discussion
National Weather Service Spokane WA
337 AM PST Mon Dec 11 2023

A couple weak systems pass this week, today and Thursday, with
opportunities for light precipitation. Otherwise a ridge of high
pressure settles in, leading to several days of low clouds and
areas of fog.



Today through Tuesday night: Areas of fog and low clouds, as well
as limited precipitation chances, linger. This morning a moist
boundary layer and weak warm advection in advance of the next
shortwave disturbance is helping to provide low clouds and fog
across large portion of eastern WA and ID. Some of the more
notable fog, per observations, is found across the Upper Columbia
Basin into the West Plains, as well as the higher hills around the
Spokane Metro and in some of the mountain valleys north of toward
the Canadian border. Ensembles keep the low clouds and fog in
place this morning, then at least start to lift the base of the
stratus between midday to mid-afternoon. Some even break up the
stratus enough to allow partly cloudy to partly sunny conditions
near the Cascades through north-central WA. That seems a
reasonable possibility as drier air comes in on the backside of
the mid-level shortwave dropping in from the west-northwest. Yet
throughout the upper Columbia Basin eastward the stratus holds on.
The shortwave will provide light rain and snow chances to
southeast WA and the ID Panhandle. The best chances for measurable
precipitation will be over the central Panhandle through the
southern Palouse, Blues and Camas Prairie. Elsewhere, the
precipitation is expected to be lighter and may just be found in
the form of drizzle.

As we go into the afternoon the precipitation potential starts to
wane from the northwest and by this evening only the Blues, Camas
Prairie and eastern Shoshone county sees lingering light rain and
snow chances. Overall snow amounts, if any, are expected to be
less than 1 inch, though with some weak instability there could be
a localized heavier burst of snow around the central Panhandle

Going into overnight and Tuesday the area generally looks drier.
However the stratus deck is expected to expand and lower again,
with fog increasing in coverage again. There may be some drizzle
and patches of freezing drizzle with the stratus. As Tuesday
progresses and the next system approaches the flow turns more
easterly, shifting the deeper stratus/low clouds toward the
Cascades and north-central WA. Some light snow or rain may be
squeezed out in the upslope flow, with the potential near the
Cascades, but this too could also be in the form of drizzle or
freezing drizzle. At this time impacts are expected to be minor,
if any with precipitation amounts not expected to be more than
trace amounts of for most. However this will be monitored,
especially if the potential for any freezing drizzle looks more
likely. /Solveig

Wednesday through Thursday night: A couple shortwaves will pass over
the region on Wednesday night and Thursday night, bringing a chance
of light snowfall over the higher elevations and a mix to the
lowlands. Impacts will be minimal with these systems as little snow
is expected. Temperatures will remain consistent, with highs in the
upper 30s to low 40s, and lows in the mid to upper 20s. With the
recent moisture along with the potential for additional moisture,
low stratus and fog could hang around in the overnight to morning
hours for much of the lower elevations. With overnight lows expected
to fall below freezing, freezing fog is also a concern.

Friday through Sunday: High pressure will build into the PacNW for
the weekend, bringing dry conditions. With the high pressure, fog
and freezing fog will continue to be a nuisance in the overnight to
morning hours. /KM


12Z TAFS: TAF sites are expected to remain impacted by MVFR/IFR
conditions over the next 24 hours, with areas of LIFR conditions
in the morning and overnight hours. A weak system dropping in from
the north today will bring a risk for -ra/-sn or just some drizzle
around GEG/SFF/COE/PUW/LWS today, with the potential waning into
this afternoon. Drier air coming on the backside of the system
will allow for some improvement toward the Okanogan Valley, but
elsewhere the main impact will be some slight lift in the stratus
through the day before it descends again later this evening into
Tuesday morning.

There is high confidence of continued restrictions over the region
with widespread stratus. Given multiple stratus layers confidence
in precise ceilings and visibility is low. There is moderate to
high confidence TAF sites will stay in IFR/MVFR conditions through
the period. There is low confidence that some VFR conditions could
develop near EAT late this afternoon and early evening.


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:


Spokane        38  31  38  25  36  28 /  30  10  10  10   0  10
Coeur d'Alene  40  31  39  24  36  27 /  30  10  10  10   0  10
Pullman        40  33  40  26  38  29 /  30  10  10  10   0  10
Lewiston       45  38  45  31  43  32 /  20  10  10  10   0   0
Colville       39  23  36  23  37  25 /  10   0  10  10   0  30
Sandpoint      38  27  37  24  38  26 /  30   0   0  10   0  20
Kellogg        40  33  39  24  41  30 /  50  10  10   0   0  10
Moses Lake     41  32  41  29  39  29 /  10  10  10  10   0  10
Wenatchee      39  31  37  34  37  32 /  10   0  10  10   0  20
Omak           39  29  38  29  38  29 /  10   0  10  10   0  20