000
FXUS66 KOTX 112338
AFDOTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
438 PM PDT Tue Jun 11 2013

.SYNOPSIS...
Breezy winds will continue into the evening with a small chance of
mountain showers or thunderstorms. The rest of the work week will
be cooler than average with the threat of showers. Thursday will
likely be the most active day for showers and thunderstorms as an
area of low pressure tracks slowly over the region. Drier and
warmer weather can be anticipated by this weekend.


&&

.DISCUSSION...
Tonight: For tonight, the Spokane forecast area will be mostly in
between a pair of weather systems. To the east, a vigorous and
progressive open wave will trigger a complex of thunderstorms over
Montana, Wyoming and the Upper Plains. Some high based
showers/virga is being picked up on the 2 PM regional radar over
the Idaho Clearwaters with this vigorous and quick moving upper
level disturbance. To the west, a slow moving 500mb low will
remain parked over Vancouver Island. As a result, the best chances
for showers and thunderstorms tonight will skirt the edges of the
forecast area with diurnally driven, widely scattered showers over
the northern Cascades in the vicinity of the Vancouver upper low.
There will also be a slight chance for showers and thunderstorms
over the Camas Prairie and Shoshone county Idaho in the vicinity
of a mid-level cold front. The NAM, GFS and SREF all suggest
another potential round of high based convection late tonight into
early Wednesday morning around Winchester, St Maries, Clarkia and
Mullan. Buoyancy progs on model soundings are marginal for thunder
late tonight in the Idaho Panhandle. The best elevated CAPE is a
bit low in the sounding to hit the sweet spot (thermally) for the
formation of graupel required for good charge separation in the
cloud. For now only a slight chance of thunder has been included
for eastern Shoshone county where the best 600-500mb lapse rates
are anticipated.

Winds for this evening have been lowered in the forecast.
Observations this afternoon over the Basin, Palouse and West
Plains have been a bit lower than anticipated. There does not seem
to be enough momentum aloft to produce widespread gusts over 25
mph. The breeziest areas this evening will likely be around
Wenatchee and over the Waterville Plateau where local gap effect
through the Cascades combined with the evening drainage off the
mountains will contribute to gusts to 30 mph through mid evening.

Wednesday: The weather for Wednesday won`t be much different than
we experienced today. A bit less pressure gradient should mean a
little less wind. Gusts up to 20 mph still look possible in the
open wheat country of central and eastern Washington. There should
be a bit more shower activity over the Cascades and the mountains
of north central Washington. 500mb temperatures over Twisp,
Leavenworth and Republic will be 2C or 3C cooler than today. There
is a small chance for thunderstorms over the Wenatchee and Chelan
burn scars, but the atmospheric profile does not look particularly
moist. Mid and upper level wind progs also suggest cells will move
to the northeast between 15 and 30 mph which should be fast enough
to decrease the heavy rain potential. /GKoch

Wednesday night through Friday night: The Inland NW will be under
the influence of a transitory upper level low which will bring
cooler than normal temperatures, showery and locally breezy
conditions. By Wednesday night, the upper level low will move
inland across western WA, while deep SW flow will funnel into
eastern Washington and a moist thetae band will set up over SE
Washington and into north Idaho. This band will contain weak mid
level instability and may be enough to spark some mid level
convection especially over north Idaho by early Thursday morning.
Meanwhile, the upper low will creep across the Cascades Thursday
morning and linger through Thursday evening. This feature will
increase surface based instability especially beneath the cold
core. Instability showers will form by late Thursday morning and
continue through the afternoon with the mountains standing the
prime area of development, although there is a chance for showers
across the entire region and locally breezy winds. The models
indicate the upper low to slowly push across the region which
should help keep storms propagating and not stall out over an
area. The model QPF does not look too impressive through Thursday
with amounts remaining under two tenth of an inch in any one area;
this seems reasonable based on PWats up to half an inch. The upper
low will weaken and fill but the remaining trough will slow down
over the Idaho Panhandle into Friday which will keep the threat of
showers continuing for the Panhandle mountains through Friday
evening. A drier westerly flow will move into the region late
Friday night accompanied by upper level ridging and increased
stability. Anticipate the showers to decrease Friday night.
Temperatures will remain on the cool side through the end of the
week. /rfox.

Weekend: The main feature of note will be a deep upper level low
pressure system that sets up somewhere just off the WA/OR coast
around 130W to 140W. In response to this developing low pressure
system will be a building ridge of higher pressure over the ID
Panhandle over into western Montana. This will place the Inland
Northwest under a southerly diffluent flow pattern. 850 mb temps
will climb substantially over the weekend from around 12C on
Friday afternoon to between 20C to 23C depending on the model of
choice. There are some differences with where the center of the
low sets up with the ECMWF solution furthest west at around 135W
and the GFS at around 131W longitude. The Canadian solution is an
outlier and was disregarded, but would suggest that the low will
set up much closer to the mainland just off the OR coastline. Both
the GEFS ensemble mean and ECMWF ensemble mean compare well with
their respective operational run, so it is difficult to place much
weight with one solution compared to the other; however, models
pushed across the low pressure system currently over western WA
too fast in their earlier depiction of that system, so I am
leaning a bit more toward the slower ECMWF solution at this time.
Temperatures where increased quite a bit as a result. High
temperatures are expected to soar above average into this weekend
with valleys in the 80s and some hotter spots possibly creeping
into the 90s.

We will be seeing some moisture pushing northward out ahead of
this low. Mid and upper level lapse rates will be rather unstable
with any showers likely capable of producing a thunderstorm. Much
of this moisture will be tied to the Cascades on Sunday and then
begin to expand eastward through Sunday night. Models show enough
upper level instability that thunderstorms shouldn`t only be
restricted to the afternoon hours and could continue to form
through the night. /SVH

Monday through Tuesday night...Unsettled weather will revisit the
Inland Northwest early next week, bringing increased chances for
showers and isolated thunderstorms. Precipitation is possible
almost anywhere as the storm system moves inland and eventually
overspreads eastern Washington and the Idaho panhandle. The
moisture fetch with this system may also bring heavier rainfall,
which could cause some flooding concerns. Still lots of time to
watch this incoming system and make necessary adjustments.
Temperatures will moderate with the increased moisture, probably
falling back to normal mid June readings by Tuesday/Wednesday. ty



&&

.AVIATION...
00Z TAFS: VFR conditions still expected over all sites through
00Z Thursday. Gusty winds will diminish shortly after sunset this
evening. Scattered showers and isolated thunderstorms will affect
the east slopes of the Cascades as well as the mountains of the
central panhandle of Idaho this evening and again Wednesday
afternoon. Most TAF sites will remain free of precipitation
throughout the period. There is a slight chance of showers in the
vicinity of KEAT and KLWS Wednesday after 21Z. Isolated
thunderstorms will also be possible near these two TAF sites, but
confidence is low. /EK


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        45  69  47  67  45  69 /   0   0  10  30  30  30
Coeur d`Alene  45  69  47  66  45  69 /  10  10  10  40  30  30
Pullman        41  68  44  65  42  67 /  10  10  10  30  30  30
Lewiston       50  75  51  72  48  75 /  10  10  20  30  30  20
Colville       44  73  46  71  45  73 /  10  10  10  40  40  30
Sandpoint      43  69  44  65  43  66 /  10  10  20  40  40  40
Kellogg        47  66  46  62  43  66 /  30  20  30  50  40  30
Moses Lake     47  75  49  74  47  75 /   0   0  10  20  10  10
Wenatchee      51  73  52  72  50  73 /  10  10  10  20  10  10
Omak           46  73  47  72  47  74 /  20  10  10  30  20  10

&&

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

$$