Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 291042

Area Forecast Discussion
National Weather Service Spokane WA
242 AM PST SUN NOV 29 2015

Low clouds and areas of fog will be common today. Strong high
pressure will contribute to air stagnation and cloudy skies in the
lowlands through Tuesday. A frontal system is expected to bring a
chance of wintry precipitation Tuesday night into Wednesday...with
more unsettled weather through the rest of the week.



Today: The lowlands of the Inland Northwest have filled with low
clouds and fog. The valleys north and east of the Spokane/Coeur
D`Alene metro have not completely socked in with fog and stratus
yet. Places like Colville, Chewelah, Sandpoint, Kellogg, and St
Joe may experience periods of sun today, but the Columbia Basin,
Palouse, and West Plains will be mired in dreary low clouds and
fog today. A few flurries may be possible out of the low cloud
deck, but probably won`t be common enough to include flurries
region-wide. High temperatures this afternoon will likely reach
the upper 20s under the stratus. For the higher elevations above
the inversion and low clouds, highs will climb into the 30s with
elevations above 3000 feet in the Cascades into the 40s with
bright sunshine.

Monday and Tuesday: We may see the low cloud deck lift a bit
Mon and Tue as our Rex Block weakens. Forecast soundings show our
inversion lifting. In theory we should see less fog as the stratus
deck rises. Overnight temperatures should be warmer under the
clouds, and our diurnal temperature spread should narrow with
lows in the low to mid 20s and highs in the upper 20s to near 30.
Pressure falls off the coast on Tuesday may be sufficient to
induce enough easterly gradient to disperse the low clouds over
the Idaho and portion of the Washington Palouse. /GKoch

Tuesday night through Saturday...A change towards a more active
weather pattern is expected in the extended forecast period.
Models differ with the precise details with timing/strength of
individual systems but all show a series of low pressure systems
tracking through the Inland NW. Most of these system will come in
from the west or southwest and bring in milder air.

However initially cold air will be in place giving light snow to
most areas Tuesday night into Wednesday morning as the first weak
system tracks through. Warmer air aloft with this system will move
into the Columbia Basin with 850mb temps warming to 1-2C which
could result in pockets of freezing rain around Moses Lake,
Ritzville, and Pomeroy areas. Given the first system is weak it is
only expected to slightly modify the low level cold air mass with
highs in the lower to mid 30s. Forecast temps are a bit below
model guidance given that models often try to warm up the valleys
too quickly in this type of scenario. This is important because
the next system quickly arrives Wednesday night into Thursday. A
warm front looks to track through the area with the focus of the
strongest lift and precipitation near the Cascades where moderate
snow accumulations are possible as cold air will be stubborn to
scrub out. Elsewhere warmer air aloft surges north with the 0C
850mb temp line Thursday morning lifting north to near the
Canadian border. This could result in pockets of freezing rain for
the northern valleys...Spokane/Coeur D`Alene area...and Upper
Columbia Basin. Temperatures are expected to warm several degrees
Thursday afternoon behind the warm front except near the Cascades.
This should bring about an end to the wintry mix threat.

The cold front follows Thursday night and Friday which should
finally give better mixing to the region. Another system
approaches next weekend...and could be a mild one with rising snow
levels once again. JW


.AVIATION... 06Z TAFS: The Columbia Basin is quickly filling in with
low clouds with all terminals but KCOE experiencing restrictions.  A
general persistent forecast is expected as strong inversions keep a
lid on the boundary a layer moisture and deliver little to no wind.
Observations indicate that a majority of this deck is 200-500 ft
AGL with visibilities greater than a mile.  There have been some
exceptions at times but they appear brief.  There is some potential
for a stronger southeast push vcnty Pullman Sunday nt aft 05z which
strong ridge aloft has promoted a strong inversion over the Columbia
will bring the best chance for improving conditions.  /sb


Spokane        26  19  28  20  30  27 /  10  10  10   0  10  50
Coeur d`Alene  28  17  29  18  31  26 /   0   0   0   0   0  20
Pullman        26  19  29  22  32  28 /  10  10  10   0  10  20
Lewiston       28  22  30  22  36  28 /  10  10  10   0  10  20
Colville       31  17  30  18  30  27 /   0  10  10   0  10  50
Sandpoint      30  18  30  17  31  25 /   0   0  10   0   0  30
Kellogg        30  18  30  16  32  25 /   0   0   0   0   0  20
Moses Lake     27  19  28  20  29  26 /  10  10  10   0  10  60
Wenatchee      27  19  28  20  29  26 /  10  10  10  10  10  70
Omak           28  19  28  18  30  26 /   0  10  10   0  10  60


ID...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

WA...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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