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Area forecast discussion 
National Weather Service Spokane Washington
214 am PDT Tuesday Sep 1 2015

Synopsis...
today will feature dry and breezy conditions. A weak cold front
brings a reinforcing shot of cooler air Wednesday along with a
chance for showers and gusty winds. A cooler and showery weather
pattern will linger over the region late week and into the
weekend.

&&

Discussion...

Today through Wednesday...long-wave trof pattern continues to
influence this portion of the forecast and beyond. Shortwaves
nested towards the center and the edges rotate around and brush
the forecast area with forcing and moisture maximizing along
the Cascade crest and near the northern Canadian border today
and tonight. A somewhat stronger frontal feature sweeps through
Wednesday with enough intensity and speed to place higher pops
in place for those same locations noted earlier and in addition
include a good portion of the north Idaho Panhandle. Southwest
winds should prevail with such a scenario allowing breezy
conditions here and there today with slightly more gusts
Wednesday. Forecast temps with such a trof in place should remain
on the cool side of normal for this time of year. /Pelatti

Thursday through Saturday...model agreement is decent and
consistent over previous runs during this period. Wednesday's cold
front will be the surface harbinger of a cool upper level closed
low descending into the forecast area from Canada. In addition to
continued unseasonably cool conditions...a showery transition
season type pattern will envelop the region as the cool air in
the center of this low produces instability each afternoon through
Friday. Thursday the shower activity will likely be concentrated
over the mountains around the basin as the upper low begins to
move in...while on Friday just about any location in the forecast
area will be subject to a hit-and-miss shower or brief
thunderstorm with the cold pocket square over the region. Both the
GFS and ec models develop a wrap around moisture band by early
Saturday over southeastern Washington and the Idaho Panhandle.

Winds during this period will be relatively light over most of
the area but the Okanogan Valley and eventually the Purcell Trench
will begin to funnel some drier Canadian Continental air into the
basin...first noticeable on Friday in the Okanogan and Friday
night/Saturday down the Purcell Trench. These terrain
constrictions could produce breezy northerly winds Friday and
Saturday.

Sunday and Monday...models diverge during this period with the
European model (ecmwf) much slower to eject the upper low to the east...implying a
continued (but improving) unsettled and cool pattern...while the
GFS aggressively moves the low out of the region and implies a
well defined warming and drying trend. Confidence is low...but
compared to previous runs the ec appears to have a more consistent
idea of a slower ejection. Thus the far reaches of the forecast
will maintain some chance of rain in the Idaho Panhandle with a
more anemic warming trend than the GFS would suggest. /Fugazzi




&&

Aviation...
06z tafs: areas of light rain will continue across the Cascade
crest and far northern Washington tonight but will not impact any taf
site. Smoke models still bring some smoke from near Pomeroy toward
the klws corridor and if this is the case, nocturnal inversions
could result in some reductions of visible until morning. Confidence
is low due to uncertainty with burning behavior of the NE Oregon
wildfire. Klws is also vulnerable to smoke from the southeast
where fires are burning in central Idaho. Some smoke is expected to
settle into the valleys of northern Washington and northern Panhandle of
Idaho. Breezy early evening winds will diminish overnight but will
become breezy again Tuesday afternoon. /Ek




&&

Preliminary point temps/pops...
Spokane 74 52 68 44 66 45 / 10 20 20 10 10 10
Coeur D'Alene 74 52 67 43 65 41 / 10 20 20 10 20 20
Pullman 76 50 68 42 66 40 / 0 20 30 10 10 10
Lewiston 83 58 73 49 71 48 / 0 10 20 20 20 10
Colville 74 50 70 40 68 40 / 10 20 30 10 20 30
Sandpoint 72 48 66 40 65 37 / 10 20 20 10 20 20
Kellogg 73 49 65 41 63 40 / 0 20 40 20 20 20
Moses Lake 77 53 73 47 71 45 / 10 10 10 10 10 10
Wenatchee 75 56 71 50 69 52 / 10 10 10 10 10 20
Omak 75 49 72 43 68 45 / 20 20 20 10 30 30

&&

Otx watches/warnings/advisories...
Idaho...none.
Washington...none.
&&

$$

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