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Area forecast discussion 
National Weather Service Spokane Washington
450 PM PDT Thursday Aug 28 2014

Synopsis...
a cool down begins across the inland northwest, with an increase
of clouds and locally breezy winds. A weak system will bring a
chance of showers to the Cascades and northern mountains Friday.
Another, stronger system arrives during the Holiday weekend. This
will result in breezy to windy conditions, along with an increased
chance for mountain showers. Temperatures will drop below normal
by the weekend, with low temperatures in the 30s possible Sunday
morning in the northern valleys of Washington and the Idaho
Panhandle.

&&

Discussion...
tonight and friday: brief ridging tonight will bring an end to
any stray showers over the northern Panhandle. A stronger
shortwave will move through the region bringing a chance of
showers to the Cascades and across the northern tier. Any
precipitation will be quite local with a very low chance of any
wetting rains for the current wildfires. Thunderstorms and the
associated threat of brief heavy rain are not expected. The main
effect of this trough passage will be gusty westerly winds.
Relative humidity is already increasing this afternoon so the
threat of combined elevated winds and low relative humidity is minimal at best.
Gusty winds will be accelerated down The East Slope gap valleys
and will spread out into the Waterville Plateau, Upper Basin and
Palouse. Gusts will be in the 20 to 30 mph range for those favored
areas. Temperatures will start a cooling trend with readings in
the upper 70s in the northern valleys to upper 80s for the lower
valleys. /Kelch

Friday nt through monday: we've focused on three main areas.
Namely...winds Friday, wind and thunder Saturday, and cool low
temps Sunday morning. Cold fropa Saturday morning will lead to
mostly sunny skies and pleasant temps Saturday, though pressure
gradients are strong enough to produce breezy conditions...especially
near the Cascades such as the Wenatchee region. We did lower only
slightly the chance of showers and thunder for NE Washington and the north Idaho
Panhandle for Saturday afternoon and evening. There are some level
of confidence issues concerning this, with model guidance not
agreeing with the strength and path of the vort Max embedded in
the upper broad trough. The trend in guidance is for less pcpn
chances, and most locations have a sfc- based cap in the afternoon
across NE WA and north Idaho. With winds decreasing overnight as skies
clear, Sunday morning lows could fall into the 30s across the more
sheltered NE WA and north Idaho valleys...the typical frost-pocket
locations. Widespread frost is not expected. Wave number 2 quickly
moves across the region Sunday and Sunday night. But this wave has
a more stratified character (and even modest isentropic ascent),
so we still kept pcpn amnts light and limited to the higher
terrain for the Idaho Panhandle and the Cascades. Mon will see a
warming and drying trend with more sunshine. Bz

Monday night through thursday: relatively benign weather is
followed by another chance of precipitation and breezy conditions
by the middle of next week. The inland northwest transitions from a
northwest to westerly flow early this period, with a relative
decrease in moisture and convective instability. One weak wave
exits through north Idaho at the start of the period, keeping a
slight shower threat here Monday night into Tuesday am. Otherwise
look for dry conditions with mostly clear to partly cloudy conditions.
Late Tuesday into Thursday the next system digs south from the
Gulf of Alaska into the inland northwest. Models disagree over the precise
evolution of this system, especially how quickly it moves in. The
ec/Gem/gefs have some agreement, as compared to the operational
GFS. Overall moisture begins to deepen this period, with a leading
warm front swinging in later Tuesday bringing the main chance of
precipitation to the Cascades. This is followed by a cold front
and unstable upper trough Wednesday into Thursday. Despite this
the bulk of the deeper moisture is above 500mbs (~15kft) and
models paint the main precipitation chances in the mountains
through Wednesday. It is not until Thursday that the moisture
deepens enough and there is enough instability to bring some
threat of showers to the Columbia Basin. The cool upper trough
will also bring some chance of thunder Wednesday and Thursday
afternoon. Expect some increase in winds, especially around
Wednesday afternoon and evening, as gradients and mixing increases
with the incoming front. /J. Cote'

&&

Aviation...
00z tafs: one wave over NE Washington and north Idaho will move
east and out of the area this evening...followed by another system
crossing the Cascades late Friday afternoon. These two features
will result in varying amounts of mid and high clouds for the taf
sites. Near the Canadian border, deeper instability early this
evening may result in isolated thunderstorms around Bonners Ferry.
Jw



&&

Preliminary point temps/pops...
Spokane 57 81 53 72 49 71 / 0 0 0 0 10 10
Coeur D'Alene 54 81 53 71 47 70 / 10 0 10 10 10 20
Pullman 50 81 49 71 44 72 / 0 0 10 0 10 10
Lewiston 60 88 59 77 54 77 / 0 0 10 10 10 10
Colville 51 82 48 75 44 74 / 10 10 10 10 20 20
Sandpoint 50 78 51 69 41 69 / 10 0 10 20 20 20
Kellogg 55 77 52 67 48 67 / 0 0 10 20 20 20
Moses Lake 55 85 51 77 48 78 / 0 0 0 0 0 10
Wenatchee 62 82 57 76 56 77 / 0 0 0 0 0 10
Omak 56 83 54 76 51 78 / 0 10 0 10 10 10

&&

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

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