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Area forecast discussion 
National Weather Service Spokane Washington
358 am PST Friday Nov 27 2015

chilly temperatures and clear skies are expected through at least
Friday as strong high pressure builds over the Pacific northwest.
Light winds and a strengthening inversion will increase the
potential for air stagnation this weekend. We will also have the
potential for areas of fog and low clouds over the weekend into
early next week. The next chance of precipitation is expected next
Wednesday with the arrival of a frontal system.



Today through saturday: a dry and increasingly stable weather
pattern will develop over the inland northwest today into
Saturday. An air stagnation advisory is in effect through the
weekend for the potential of air pollution build up given the weak
winds and stable conditions. Mid-level subsidence will intensify
our low level inversion over the next 36 to 48 hours making for a
difficult temperature forecast. Elevations above the inversion
will become increasingly mild with highs in the upper 30s to 40s
while low elevations may not get out of the upper 20s and lower
30s. Our surface winds will be light today into the weekend.
Without the low level mixing the wind provides, temperatures may
struggle to warm especially in The Lowlands with snow cover. MOS
guidance does forecast cooler afternoon temperatures for most
areas today compared to yesterday, but MOS has performed poorly
the last couple of days suffering a cold bias of 2 to 5 degrees.
With that in mind, the forecast for today and Saturday are a
couple degrees warmer than the GFS MOS. Fog has been slow to
develop early this morning. The evening sounding at Spokane was
exceedingly dry in the low levels, so despite narrow
temperature/dewpoint spreads it may take another night or two
before our air mass moistens through local evaporative/sublimation

Sunday: the fog and low cloud potential will be on the rise early
Sunday morning and again Sunday night into Monday morning. Our
current air mass is quite dry so the confidence level for fog
development is rather low at this time. It is possible that mainly
clear skies could persist into Sunday or possibly Monday. /Gkoch

Monday through Thursday...models are in good agreement of an upper
ridge over the area on Monday before the ridge moves east for
Tuesday into Wednesday. With the ridge over the area on Monday
a continuation of a stagnant weather pattern continues with low
clouds and patchy fog expected for most valleys while the
mountains should be mostly clear. As the ridge moves east on
Tuesday a large low in the Gulf of Alaska will send multiple
systems across the inland northwest Tuesday night through Thursday.
Confidence is low in the details due to run to run inconsistencies
with both the GFS and European model (ecmwf) solutions. Initially the air mass will
be cold allowing for snow to fall. How quickly the region warms up
will depend on the strength of incoming systems and how much low
level mixing they provide to scrub out the cold air. It is also
possible that a period of freezing rain could occur in some areas before
the transition to rain. The northern valleys (especially the
methow) will be the slowest to warm up and should see primarily
snow during this period. Jw


12z tafs: area web cameras and the satellite fog channel show
patchy shallow fog in a few spots in the inland northwest this
morning. Sandpoint, Bonners Ferry, and south of Moses Lake. Fog
should dissipate by late morning giving way to sunny skies. Patchy
fog will become a possibility for Lewiston and Moses Lake early
Saturday morning and into the other taf sites (kgeg, ksff, keat,
kpuw) by Sunday morning. /Gkoch


Preliminary point temps/pops...
Spokane 32 17 31 17 30 17 / 0 0 0 0 0 0
Coeur D'Alene 32 17 32 18 31 19 / 0 0 0 0 0 0
Pullman 33 18 32 19 33 21 / 0 0 0 0 0 10
Lewiston 33 21 33 22 33 24 / 0 0 0 0 0 10
Colville 35 17 35 18 34 19 / 0 0 0 0 0 0
Sandpoint 30 16 32 17 30 22 / 0 0 0 0 0 0
Kellogg 32 16 35 17 34 22 / 0 0 0 0 0 10
Moses Lake 35 15 33 16 31 19 / 0 0 0 0 0 0
Wenatchee 35 21 33 22 31 21 / 0 0 0 0 0 0
Omak 32 18 35 19 33 21 / 0 0 0 0 0 0


Otx watches/warnings/advisories...
Idaho...air stagnation advisory until noon PST Monday for central
Panhandle mountains-Coeur D'Alene area-Idaho Palouse-Lewis
and southern Nez Perce counties-Lewiston area-northern

Washington...air stagnation advisory until noon PST Monday 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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