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Area forecast discussion 
National Weather Service Spokane Washington
1049 am PDT Tuesday Sep 16 2014

Synopsis...
today into Wednesday will feel like Summer with afternoon
temperatures in the 80s. Cooler, more seasonal temperatures will
follow the passage of a weak cold front on Wednesday night.
Thursday will be locally breezy with a chance for light rain
showers. Sunshine and light winds will return on Friday, and look
for warm temperatures once again this weekend.

&&

Discussion...

Today through Wednesday night...ridge deamplification and
propagation of the ridge axis eastward continues during this time
interval. This opens up the door for approach of shortwave
disturbances from the south and southwest. Elevated moderate
instability and moisture merit continued mention of sprinkles in
the forecast roughly south and east of a line from Ritzville to
Plummer. Wednesday into Wednesday night the ridge is displaced
even further east in Montana and the flow becomes more southerly
as an offshore low pressure system works its way to northwest and
towards the coast. This necessitates continued mention of showers
along the Cascades and up north near the British Columbia border.
As to be expected with the loss of the ridge a slight cooling
trend with increase cloud cover remains. Additionally the winds
should prevail more from the south tonight and Wednesday. /Pelatti

Thursday: the most active weather day of the week should be
Thursday following the passage of a weak cold front Wednesday
night. It is tough to get too excited about much significant
shower activity Thursday. The 0z models agree that the incoming
500mb trough will move inland in pieces with the low amplitude
northern branch shortwave tracking along the U.S/Canadian border
and the moisture rich southern branch wave moving through
California. The NAM and GFS forecast the best combination of mid-
level instability and surface based cape over the Idaho Panhandle
Thursday afternoon. Our forecast includes a slight chance of
thunderstorms for places like Bonners Ferry, Sandpoint, Kellogg,
and St Maries. Marginal instability and weak deep layer shear
suggest that any convective cells will be rather unorganized. At
this time, the threat of strong storms looks to be very low.

Breezy west winds should develop Thursday afternoon through the
Cascade gaps, Columbia Basin, Palouse and West Plains. 850mb winds
in the 20-25kt range suggest that gusts will top out close to
25mph in the afternoon and early evening.

Friday: a transition to a drier northwest flow in the 700-500mb
layer is expected to occur on Friday and Saturday. There may be
enough shallow mid-level instability on Friday for widely
scattered showers over the mountains of the Idaho Panhandle and
along the Cascade crest. Elsewhere, fair weather cumulus and near
normal temperatures should be the norm on Friday.

Saturday through monday: a return of high pressure ridging over
the weekend will bring sunshine, warm temperatures, and light
winds to the region. The dry air mass, light winds, and
increasingly long nights will promote large diurnal temperature
swings. Chilly nights and warm afternoons. /Gkoch

&&

Aviation...
18z tafs: moisture advecting into the region from the south has
resulted in bands of mid and high level clouds draping across much
of the region this morning. Some obs have shown traces of precip
with these, but that will be about the extent. As these clouds
continue to drift north, expect a gradual clearing through the day
and overnight. Our next approaching system will have clouds on the
increase once again after mainly 12z tomorrow. Visible has been
reduced at times at kpuw due to smoke passing through the area.
Expect this to lift this afternoon as the atmosphere becomes
better mixed promoting VFR conditions. /Fliehman



&&

Preliminary point temps/pops...
Spokane 86 56 83 57 78 56 / 10 10 10 10 20 20
Coeur D'Alene 87 52 83 53 78 55 / 10 10 10 10 30 20
Pullman 86 53 84 53 79 53 / 10 10 10 10 20 10
Lewiston 92 61 89 61 83 59 / 10 10 10 10 20 10
Colville 89 50 83 51 80 51 / 0 10 10 20 20 20
Sandpoint 83 47 78 48 75 52 / 10 10 10 10 30 30
Kellogg 84 54 80 53 74 52 / 10 10 10 10 30 30
Moses Lake 89 56 86 58 82 56 / 0 10 10 10 10 10
Wenatchee 88 61 85 62 80 60 / 0 10 10 20 10 10
Omak 90 55 86 57 80 55 / 0 10 10 20 20 10

&&

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

$$

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