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Area forecast discussion 
National Weather Service Spokane Washington
513 am PDT Tuesday Jun 2 2015

Synopsis...

An upper trough lingers across the Pacific northwest through
mid week, with a continuing scattered shower and isolated
thunderstorm threat. The pattern begins to dry out for the end of
the work week and most of the weekend. Temperatures Tuesday and
Wednesday will be relatively cool, then much warmer weather is
expected Friday through the weekend, with high temperatures in the
mid 80s to low 90s.



&&

Discussion...
today: the threat of showers and thunderstorms will continue.
Satellite and radar shows the counterclockwise circulation around
the mid-level trough centered near the Pacific northwest coast. There are
several shortwaves embedded in the flow around that trough. A few
will continue to impact eastern Washington and north Idaho. So with that
said, there two regions of the inland northwest that have the best threat
of precipitation.

The first region will be the counties bordering Canada and in
particular closer to the Canadian border itself. The shortwave
that entered yesterday is moving toward the Canadian border this
morning. Tack on the lingering deformation axis/surface trough and
the southerly flow and pockets of instability, this will keep the
overall highest precipitation chances alive here. The precipitation
that falls across the north may be steadier and moderate at
times. However the periods of torrential downpours is not
expected at this current time. So the risk of widespread flooding
will be on the wane.

The second region will be from the Blue Mountain, Camas Prairie
and higher Palouse into the central Panhandle. A couple smaller
scale shortwaves were coming up through northeast Oregon into
southeast Washington this morning. These will continue their northeasterly
track through the day. Another shortwave was pushing into
southwestern Oregon this morning too and it's projected to track
toward southern Washington and lower Idaho later this afternoon and evening.
These features, a boundary stalled across Oregon through central
Idaho and a ribbon of instability (100-500 j/kg of cape and Lis
between -1 and -3 c) will make this area a modest threat of
precipitation too.

The remainder of the inland NW, from the Cascades and Waterville
Plateau out through the Columbia Basin and Spokane/c'da will also
see precipitation threat too. First closer to the Cascades and
Waterville Plateau a lingering deformation axis and steepening
lapse rates through the afternoon will bring at least isolated to
scattered showers threat. However as the afternoon wears on into
evening and a slot of drier air begins to nose in, the threat will
wane. Farther east toward the Spokane/c'da are and lower Palouse,
the smaller scale shortwaves coming in from the southeast will
bring a shower and thunder threat here too. However being on the
fringes of the shortwaves the showers are expected to be more
isolated to widely scattered in nature.

Overall the threat of significant thunderstorms will not be as
great as Monday. Instability, by comparison, is not as great and
the surface trough begins to fill. If there are any stronger
storms, the best threat appears will be toward The Blues mountain
and southern Panhandle, where 0-6km shear values are between
20-30kts. Its not too impressive, but better than the remainder of
the County Warning Area.

Expect temperatures near to slightly below seasonal averages with
the upper trough and its cooler core in the region. /J. Cote'

Tues nt through Fri: for the first 24 hours of the fcst, we'll
have to deal with at least two vort maxes feeding the broad upper
low that remains more or less stationary over the pac NW until
thurs morning before the long-wave pattern steering flow splits
and allows an upper ridge axis to build into the region from the
west. Keeping the fcst based on pattern recognition in this
uncertain and unstable wx regime, Tue nt through thur morning
will be dominated at least partly by diurnal effects...with
afternoon heating combining with steep lapse rates and lg-scale
forcing from the vort maxes to keep a nearly continuous threat of
showers and thunder in the fcst each day. The first dry fcst will
be thurs evening and Fri coincident with the strengthening upper
ridge. Bz

Saturday through monday: a relatively quiet weather period is
expected over the weekend as a ridge pattern is in place over the
region. The only chances of precip will mainly be in the Idaho
Panhandle and Camas Prairie as low moves into central Idaho from
northern California bringing slight chance of precip and an isolated
thunderstorm during the peak heating of the day Sunday and
Monday. The temperatures will be the main issue as temperatures
are expected to be around 15 degrees above the season normals. The
highs are expected to be in the low 80s to 90s for this period.
/Jdc

&&

Aviation...
12z tafs: an upper trough lingers in the region and shortwaves
rounding it will produce a threat of light precipitation, along
with some breezy conditions this afternoon. This morning, a -ra
threat will be found especially near puw/lws/Coe, with more widely
scattered to isolated shower threat elsewhere. There could be some
thunder in the afternoon, but the risk around any single taf is
too low to include as a predominant weather. Winds increase
through the day, with some gusts around 20 or 30 mph possible in
the afternoon. The shower threat and winds abate after 01-05z. In
general VFR conditions are expected, but localized MVFR cigs are
possible around showers, especially near kcoe. Late tonight into
Wednesday morning there will be some lower stratus and perhaps
patchy fog threat, but the risk at this times is low. /J. Cote'.




&&

Preliminary point temps/pops...
Spokane 66 50 69 50 73 53 / 50 20 20 20 20 20
Coeur D'Alene 64 49 68 48 73 49 / 60 40 30 30 20 20
Pullman 64 45 67 44 71 47 / 60 40 20 20 20 10
Lewiston 71 52 74 52 78 55 / 40 40 30 20 20 10
Colville 66 50 70 48 76 50 / 90 70 40 40 30 20
Sandpoint 63 49 67 47 73 47 / 90 60 60 40 30 30
Kellogg 63 45 67 44 72 46 / 80 50 40 30 20 20
Moses Lake 73 51 75 51 79 54 / 20 20 20 20 10 10
Wenatchee 70 54 73 55 79 59 / 20 20 20 20 10 10
Omak 68 50 71 49 79 51 / 70 50 50 40 30 20

&&

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

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