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FXUS66 KOTX 172343
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
343 PM PST Sat Nov 17 2018

.SYNOPSIS...
The majority of the Inland Northwest will enjoy sunshine this
weekend. Lowland fog and clouds will likely become more prevalent
Monday and Tuesday. The weather pattern will become more active
starting Wednesday, just in time for Thanksgiving travel.
Snow in the mountains is expected, possibly impacting Cascade
mountain pass travel.


&&

.DISCUSSION...

Tonight: The Inland Northwest experienced a push of dry air
overnight that continued into the day today. Surface dewpoints
over the majority of eastern Washington and northern Idaho have
fallen into the lower to mid 20s. Our low level air mass should be
dry enough that the majority of our region should remain free of
fog overnight. However, the Lewiston-Clarkston Valley and up the
Clearwater River will have a good chance of fog and low clouds
again tonight. Surface dewpoints remain in the lower to mid 30s in
these areas that are sheltered from our dry northeast winds.

Sunday: There should be an abundance of sunshine on Sunday. The
day will begin chilly with most lowland communities in the Inland
Northwest in the 20s at sunrise. Afternoon highs have been hedged
toward the warmer GFS MOS guidance. Warmer MOS temps verified
better this afternoon (Sat) in areas that received sunshine.

Monday and Tuesday: Low clouds and fog will likely become more
widespread early in the week as our low level air mass modifies.
Look for surface dewpoints to increase Sun, Mon, and Tue. As this
occurs, fog and low clouds will likely develop in the Lower
Columbia Basin around Walla Walla and Tri Cities Sunday and Sunday
night. By Monday and Tuesday, gloomy conditions will likely expand
northward into Moses Lake, Wenatchee, and Grand Coulee. The
valleys of Northeast Washington will also have a high probability
of generating fog and low clouds Sunday night and again Monday
night. The clouds generated in the valleys around Colville, Deer
Park, and Sandpoint may expand into Spokane and across the West
Plains Monday or Tuesday. /GKoch

Wednesday and Thanksgiving: The ridge axis has moved east over
the continental divide. This will open up the Pacific Northwest to
an increased chance of precipitation beginning Wednesday. Have
slowed down the timing a bit for the start of rain and snow.
Through the day precipitation won't make it much past the
Waterville Plateau or Moses Lake. Then during the evening and
overnight hours it will move east into eastern WA and north ID. A
series of weather disturbances will move through the southwest
flow, which will keep mainly mountain snow and valley rain going
through Thursday night.

Current forecast thinking is accumulating snow will be confined to
the mountains. The main impact would be along Highway 2 from
Cashmere to Stevens Pass, and Highway 20 impacting Sherman Pass
and the North Cascades Highway. Mountain accumulations would
generally be 1 to 3 inches. The northern valleys may see snow
during the early morning hours on Thursday, but it will likely
only stick to grassy surfaces.

Late Thursday night into Friday morning winds will increase as a
stronger weather disturbance moves in. This will keep the
atmosphere more mixed, and keep many valley temps at or above
freezing through the night. Mainly our known 'colder' locations
such as the Methow valley, Republic, Deer Park will be below
freezing.

Friday and Saturday: Winds will continue through the morning and
early afternoon hours, mainly impacting the Columbia Basin,
Palouse and Spokane area. Precipitation will be on the decrease
through the day Friday with the best precip chances by Saturday
mainly across the Cascades and north ID Panhandle. Temperatures
will lower a few degrees from earlier in the week. Highs in the
mid 30s to mid 40s and lows in the mid 20s to lower 30s is
expected. /Nisbet

&&

.AVIATION...
00Z TAFs: Clear skies and light winds are expected tonight through
Sunday for much of north Idaho and eastern Washington. Our airmass
is quite dry with dewpoints in the low to mid 20s...except for the
valleys of the southern Idaho Panhandle. The redevelopment of fog
and low clouds is likely at Lewiston ID. After hours of thick fog
this morning, skies finally cleared during the mid afternoon.
Surface dewpoints remain in the low to mid 30s in the Snake and
Clearwater valleys suggesting redevelopment of fog overnight.
Without much low level wind expected, if fog develops at LWS
again, it will likely linger into the afternoon. /GKoch


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane 25 41 26 43 25 43 / 0 0 0 0 0 0
Coeur d'Alene 23 41 25 44 25 45 / 0 0 0 0 0 0
Pullman 25 45 28 47 28 48 / 0 0 0 0 0 0
Lewiston 27 40 29 43 29 48 / 0 0 0 0 0 0
Colville 26 43 26 40 25 40 / 0 0 0 0 0 0
Sandpoint 23 41 25 43 25 44 / 0 0 0 0 0 0
Kellogg 26 42 27 45 28 46 / 0 0 0 0 0 0
Moses Lake 21 43 22 39 23 41 / 0 0 0 0 0 0
Wenatchee 26 43 27 42 27 39 / 0 0 0 0 0 0
Omak 24 40 25 44 24 42 / 0 0 0 0 0 0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Air Stagnation Advisory from 7 AM Sunday to 1 PM PST Wednesday
for Central Panhandle Mountains-Coeur d'Alene Area-Idaho
Palouse-Lewis and Southern Nez Perce Counties-Lewiston Area-
Northern Panhandle.

WA...Air Stagnation Advisory from 7 AM Sunday to 1 PM PST Wednesday
for East Slopes Northern Cascades-Lower Garfield and Asotin
Counties-Moses Lake Area-Northeast Blue Mountains-Northeast
Mountains-Okanogan Highlands-Okanogan Valley-Spokane Area-
Upper Columbia Basin-Washington Palouse-Waterville Plateau-
Wenatchee Area.


&&

$$
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