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Area forecast discussion...updated 
National Weather Service Spokane Washington
1116 am PDT Sat may 30 2015

Synopsis...
strong thunderstorms will be possible in the Idaho Panhandle and
in the northeast mountains this afternoon; large hail, gusty
winds and heavy rain will be the main threats. Thunderstorm
chances will lessen on Sunday and are expected to be more confined
to southeast Washington and north central Idaho. Meanwhile most
locations will see very warm temperatures with highs in the 80s
through the weekend. Thunderstorm chances will increase markedly
on Monday into Tuesday as a strong upper level trough moves in
from the south. Some of the storms on Monday could be strong.
Unsettled and cooler weather will persist into the remainder of
the work week with a threat of showers and thunderstorms each day.



&&
Update....
scattered showers and thunderstorms across north Idaho will continue
through noon. The showers and thunderstorms that moved through NE
Washington and north Idaho this morning was just round one today. Low pressure
sitting in British Columbia along with a decent wave moving north
just offshore of northern California will provide enough 'squeeze' across
our area this afternoon for another round of showers and
thunderstorms...this time more widespread and stronger. The
showers earlier today just helped to moisten the atmosphere and we
are getting some clearing to the west which will allow for good
heating at the surface to get cumulus to start to build across
the region. The main impact area today for stronger storms will be
northeast Washington and north Idaho...Stevens, Ferry, Bonner and boundary
counties. General thunderstorms is possible across all of eastern
Washington and north Idaho today. Threat being torrential rains, gusty winds
and hail. /Nisbet

&&
discussion...
..isolated strong to severe thunderstorms possible in the central
to northern Idaho Panhandle and northeast Washington mountains
by midday and into the afternoon...

Today: an upper level low pressure system will sit over central
British Columbia. The eastern half of the region will remain unstable today, but
the wester portion of the region will dry out as drier air pushes
through the Cascade gaps. This will keep the active weather
northeast of a line from Omak to Walla Walla. Much of the eastern
portion of the region is very moist early this morning with p-wats
up over 0.90 inches. Although these p-wats will see a slight
downward trend through this afternoon, the atmosphere will remain
moist across this portion of the region. There is a lot of cloud
cover this morning with isolated to scattered showers and
thunderstorms developing from the Okanogan Highlands down to the
Camas Prairie. Much of these showers are very wet with heavy rain
being observed underneath the stronger cores. These showers will
keep the primer pumped for more afternoon thunderstorms in the
afternoon. Dew point temps are expected to be in the mid 50s in
the Panhandle and over the northeast mtns. Clouds are also
expected to be clearing to the east by the late morning, which
should allow for good surface heating. Models are indicating some
impressive looking surface based CAPES of between 1000-2000 j/kg.
There will also be a modest amount of shear of around 30 kts
between 0-6 kms. Winds also will veer with height, which will help
to generate some rotation with any thunderstorms that develop.

There is a limiting factor for developing convection and that is
there is no discernible kicker. In other words, there isn't a
shortwave that will pushing across the region to help generate
convection like what was observed yesterday. With the upper level
low in central BC, it may be close enough to generate some weak
divergence across the northern mtns. In addition, there will be a
weak jet streak that sets up from northwest Washington to the central
Panhandle mtns. This would also help to create some additional
lift in the left exit region across the northeast portion of the
region (albeit weak). With that said, surface based CAPES off of
the models are strong for this portion of the region this time of
year. There will also be little to no cin to overcome as well.
This alone should be sufficient to get convection going. Some of
these storm are expected to become strong and isolated severe
thunderstorms is not out of the question. The primary hazard will
be for large hail and gusty outflow winds. Heavy rain is also
expected, but storms should also be moving at a decent pace to the
northeast. This should limit the possibility for flash flooding
impacts.

Tonight into Sunday morning: convection should wane quickly with
sunset. This will result in more benign weather overnight. There
will be the possibility for some fog developing by early Sunday
morning depending on how much additional rainfall is observed
today. Best potential for fog would be in the northern Panhandle
and in the northeast mtns. /Svh

Sunday through saturday: Monday will be the potentially big wx
day as far as thunder potential as a tongue of high Theta-E air
surges northward ahead of the ejecting vort Max that will lift north
up the Pacific NW coast. This conveyor belt of higher Theta-E air
will provide favorable ingredients that will combine with the
large- scale lift of the ejecting short- wave trough to
potentially initiate strong thunderstorms that will expand NE
through ern Oregon and into north Idaho and ern WA. Uncapped cape of
500-1000 j/kg will combine with modest deep lyr shear of 20-30kts.
This should be plenty sufficient to produce bands of embedded
strong thunder comparable to what we saw last afternoon and
evening...though farther east closer to north Idaho. Sref guidance
also supports this slightly farther east corridor of highest thunder
threat favoring hail and gusty winds. Tues, however, will be a
tougher thunder fcst as most model guidance brings the low far
enough inland that the deepest instability from Mon is quickly
shunted east into wrn Montana. The tues through Fri period will
resemble closely the wx regime we experienced earlier this week
with the upper low overhead...with a resurgence of showers and
thunder every afternoon where it's not already showering. There's
no way we can get around broad-brushing this type of regime given
the high level of confidence we have that pattern recognition
supports the heaviest showers every afternoon. Bz

&&

Aviation...18z tafs: a very unstable atmosphere will remain fixed
over the eastern third of Washington and the Idaho Panhandle
through at least 00z. This will lead to a chance of thunderstorms
by this afternoon...with the best chances likely impacting geg sff
and Coe with smaller chances at puw and lws. We did not put
prevailing thunder in the forecasts since the hrrr has
consistently kept the bulk of the thunder north and east of geg-
Coe as well as east of puw-lws. Nonetheless not confident that
will pan out as the atmosphere is quite ripe for convection with
clearing skies moving in from the west-southwest which should tap
into this instability. Thunderstorms will be capable of small
hail, gusty outflow winds, frequent lightning strikes and
torrential rainfall. Drier air across the Cascades will quickly
eradicate the thunder chances between 00z-02z with the last
remnants hanging on over the northern Panhandle. Remainder of the
forecast should see dry weather with VFR conditions.



&&

Preliminary point temps/pops...
Spokane 82 57 83 59 77 52 / 40 10 10 10 60 70
Coeur D'Alene 81 55 82 57 77 52 / 50 30 10 10 60 70
Pullman 79 55 82 56 75 49 / 30 10 10 20 70 60
Lewiston 87 62 89 63 82 56 / 30 20 20 20 70 70
Colville 82 53 86 56 80 54 / 60 20 10 10 60 80
Sandpoint 74 52 80 54 76 51 / 80 50 10 10 70 80
Kellogg 77 53 80 55 74 49 / 60 30 20 20 70 80
Moses Lake 90 57 88 62 83 55 / 0 0 0 10 50 50
Wenatchee 89 60 86 63 80 56 / 0 0 0 10 60 70
Omak 89 52 85 56 81 53 / 20 10 0 10 70 80

&&

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

$$

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