Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 302329
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
328 PM PST FRI JAN 30 2015

.SYNOPSIS...
Areas of low clouds and fog will persist across portions of
Inland Northwest as high pressure remains in place. The ridge of
high pressure will begin breaking down Sunday. This will result in
in a good chance for rain and snow through much of the upcoming
week.

&&

.DISCUSSION...
Tonight and Saturday...Fog and stratus will continue to plague
the valleys of the Inland Northwest into Saturday. There will be
one suttle difference however compared to today. A mid level wave
seen on satellite over central British Columbia this afternoon
will slide southeast into southern Alberta tonight and then into
Montana on Saturday. As it does so boundary layer winds will
increase to 5-10 kts out of the south-southwest. This will provide
an upslope flow into the rising terrain of Northeast Washington
into the Idaho Panhandle with the Canadian, NAM, and ECMWF hinting
showing a small area of light qpf mainly from Colville to Spokane
east into the Idaho Panhandle overnight tonight into Saturday
morning. Soundings indicate a good chance of at least snow
flurries...but may also see pockets of drizzle or light freezing
drizzle. The increased wind in the boundary layer should favor
more stratus tonight compared to fog...although locally dense fog
will remain possible especially this evening on the west plains
from Davenport to Airway Heights. As this system pulls away from
the area into the afternoon winds will be light...with stratus
likely persisting into the afternoon. JW

...A pair of wet winter storms are expected Sunday and again
   late Monday...

Saturday night through Monday night...While the models are still
showing some timing differences with individual weather
features...it`s clear that the pattern will change and become
wetter through this period. Guidance has slowed the onset of the
precipitation on Sunday...but are also showing higher amounts of
precipitation. Valley rain and mountain snow can be expected
Sunday through Monday night.


*Precipitation: Confidence is high that all locations will see
 measurable precipitation...with amounts ranging from .10-.20 in
 the deep basin to .50 to right around 1.0 for the mountains. The
 areas with the best orographic flow will be the big
 winners...such as the crest of the Cascades and the Panhandle
 mountains. The moisture will come in two waves. Precipitation
 will begin along the Cascades early Sunday morning then push
 across the forecast area through the day. A weak cold front will
 follow Sunday afternoon for a drying trend from the west. Of
 course up-sloping flow into the Panhandle mountains will result
 in continued higher pops up there. The second warm front will be
 similar dynamically and begin late Monday morning...with the cold
 front following Tuesday evening. So there will not be much of a
 break in between. For the northern any eastern mountains there
 may not be any break.

*Precipitation type: Snow levels Sunday morning will begin around
 3k feet across the south and the valley floors north of line
 roughly along I-90, then rise through the day. At this time it
 looks like measurable snow will be likely north of Highway 2
 including The Spokane- Coeur D`Alene corridor. Snow amounts
 between Highway 2 and the Columbia river may be around an inch
 for the Waterville Plateau...the northern Basin and for the
 Spokane-Coeur d`Alene areas. The northern mountain valleys may
 see 1-2 inches and locally up to 3 inches and the mountains 3-5
 and locally more for the higher elevations. People traveling
 after the Super Bowl Sunday evening will want to be aware of
 changing road conditions.

For the Monday afternoon-Tuesday morning event snow levels will
continue to rise. Locations below 3-3.5K feet should see mostly
rain...if not a little snow/rain mix to start out, with little to
no accumulation. The mountains should get 3-6 inches and locally
higher above 5k feet. No highlights are expected at this time, but
we will hit this in our discussions and social media.

*Temperatures will range from lower 30s across the north to mid
 40s across the south. This will be at or slightly above normal
 across the south and at or below normal across the north.
 Temperatures will then rise 3-4 degrees on Monday and be on the
 warm side of normal. Tobin

Tuesday through Friday: The moist westerly flow buckles on
Tuesday as a shortwave trough drops down from northern BC and
carves a trough across the Inland NW, while a ridge of high
pressure rebounds in the northern Pacific. This pattern will push
a surface cold front in from the north across the region on
Tuesday. Anticipate a band of precipitation with this boundary,
but there looks to be plenty of drier and colder air on the back
side of the front that will help clear out the cloud cover and
generate some clearing. The threat of showers will linger over the
Blue mountains and the southern ID panhandle into Tuesday evening
under favorable orographic lift. The period of Tuesday through
Wednesday tends to be the drier period of the week yet high
pressure may bring some patchy fog to the valleys. The models
start to diverge by Wednesday with the ECMWF showing a secondary
shortwave trough flattening the ridge and rolling into the region
with a chance of valley rain and mountain snow. The GFS keeps a
stronger ridge in place off the coast with continued orographic
showers for southeast Washington and the southern ID panhandle. At
this time, will compromise between the solutions with pops across
extreme eastern Washignton and a better chance of north Idaho.
This will give a chance of valley rain and mountain snow. This
slightly unsettled trend will continue into Wednesday night. As
temperatures cool overnight, may see a small chance of mixed
precipitation in the valleys while the mountains stand the best
chance of snow. Then by Thursday and Friday, a warmer and wetter
pattern is anticipated to move across the Inland Northwest. The
next storm system will arrive from the central Pacific with a good
tap of moisture. The models agree on this storm system to flatten
out the ridge and bring a series of warm fronts into the region.
This will bring a better chance of valley rain and mountain snow.
Snow levels will be on the rise, but sheltered northern valleys
may be slow to warm up and could experience a chance of freezing
rain Thursday night across the northern valleys before the warm
air finally penetrates across the north. /rfox.

&&

.AVIATION...
00Z TAFS: Light winds and clear skies aloft will continue to
bring widespread restrictions from fog and stratus through the
next 24 hours. A weather system passing to the north will increase
boundary layer winds tonight out of the south-southwest which
should help raise the stratus deck slightly for
KGEG/KSFF/KCOE/KPUW. However low level upslope and a deepening
stratus layer will favor an increase in -FZDZ and very light snow
or flurries which should hold CIGS to IFR or lower. The stratus
layer is expected to lift Saturday afternoon with IFR/MVFR CIGS
common. JW

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        28  34  29  36  32  37 /  10  10  10  60  50  80
Coeur d`Alene  30  34  28  35  32  38 /  10  10  10  60  60  90
Pullman        31  37  32  40  36  44 /  10  10  10  60  70  90
Lewiston       35  43  33  44  37  48 /  10  10  10  50  60  70
Colville       32  36  28  35  30  34 /  10  10  10  60  50  60
Sandpoint      29  34  26  34  30  35 /  10  10  10  70  70  90
Kellogg        29  37  27  35  33  37 /  10  10  10  80  80  90
Moses Lake     34  39  31  39  31  41 /   0   0  10  40  20  50
Wenatchee      33  38  31  39  32  40 /   0   0  10  40  30  40
Omak           33  37  31  37  30  35 /   0   0  10  40  20  40

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$



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