Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Spokane Washington
439 PM PDT Sat Apr 19 2014

Synopsis...
a storm system will bring windy conditions this afternoon and
tonight with some showers mainly for the mountain zones. Easter
Sunday should be mild and mainly dry. After a warm and dry Monday,
a cool and unsettled weather pattern will return Tuesday and
linger through much of the week.

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Discussion...
tonight through Sunday...most of the weather this period will be
in response to the cold front currently pushing into the Cascades.
Model solutions are handling the positioning of the front and
continue to push it through the remainder of eastern Washington
and north Idaho through early evening. The latest radar images are
showing some showers along and ahead of the front...however with a
fairly dry sub-cloud layer in place...not much is hitting the
ground. This drying is also being aided by the downslope westerly
flow over the Cascades. Although we won't entirely rule out the
chances for precipitation hitting the ground over the Okanogan
Valley...western Columbia Basin and Wenatchee area...it likely
won't be enough to soak the ground. As the front moves into the
eastern third of Washington and north Idaho the chances will
increase as the in situ sub-cloud layer is more moist while...the
same southwest mid-level flow will lead to general ascent. Any
precipitation which falls won't be heavy as the front is trailed
by a swift moving upper level shortwave trough. The threat of
precipitation will wane rapidly overnight as drier air slides into
the region behind the front. Winds will also increase steadily
behind the front and passage of the shortwave trough. Fine
resolution models are showing winds gusts of 30-35 mph by late
afternoon into the evening across the southern Columbia
Basin...Palouse...and Blue Mountains. The peak winds will likely
occur between 4pm and 9pm...then slowly subside overnight.
Sunday's weather looks tranquil as a shortwave ridge temporarily
builds over the region. A few of the models are showing some
residual instability and light showers over the extreme eastern
Panhandle and near the Cascade crest...but suspect that is
overdone based on model soundings in those areas. Fx

Sunday night through tuesday: the upper level ridge will begin to
shift east Sunday night as an elongated upper level trough nears
the West Coast. The trough will begin to move onshore Monday night
and swing into the inland northwest Tuesday for an increased
chance of precipitation. While most of the energy associated with
the trough will dig south into California, there is still decent
dynamics across our area on Tuesday as the trough becomes
negatively tilted.

Have kept the forecast dry Sunday night. Monday keep the chance of
precip mostly along the Cascade mountains. Monday night
precipitation starts to move east across the state, and by Tuesday
most locations will be receiving rain. Rain amounts will generally
range from 0.10 or less across The East Slope valleys and Columbia
Basin to 0.30 along the Cascade crest and mountains of northern Washington
and north Idaho. Models are showing decent instability Tuesday
afternoon across north-central Washington and have therefore added a
slight chance of thunderstorms. Clouds will be on the increase
Monday into Tuesday. Monday temps will be 5-10 degrees above
average for this time of the year and then Tuesday with the trough
passage temps will drop down to about 5 degrees below average for
this time of the year. /Nisbet

Tuesday night through Saturday...an upper level trough will keep
cool and unsettled conditions across the region Tuesday night and
Wednesday. Post frontal gusty winds will keep temperatures from
falling below freezing for most valley locations. Daytime
temperatures will be on the cool side of normal while the cold
upper trough remains overhead, especially for the eastern zones
where instability showers will be more numerous in westerly
upslope flow. Brief ridging Wednesday night will be shunted east
by the next Pacific trough. This system will be slow to transition
east so the region will be in very moist and energetic flow aloft
for the rest of the work week and into next weekend. This will
bring a good chance of precipitation each day along with
temperatures near seasonal normals. /Kelch

&&

Aviation...
00z tafs: a passing cold front will bring some light showers
and/or sprinkles to the aviation area along with some gusty/windy
conditions into the early evening however VFR conditions expected
at all forecast sites through 00z Monday.Winds will decrease
overnight and into Sunday with clearing skies expected. /Pelatti

&&

Preliminary point temps/pops...
Spokane 35 58 39 67 44 54 / 20 0 0 0 50 70
Coeur D'Alene 35 57 37 68 46 54 / 30 0 0 0 40 70
Pullman 35 57 39 68 44 52 / 20 0 0 0 50 70
Lewiston 41 63 42 75 49 57 / 20 0 0 0 40 60
Colville 34 64 35 71 41 59 / 30 10 0 10 50 60
Sandpoint 35 57 35 67 43 53 / 50 10 0 0 20 70
Kellogg 36 55 35 68 41 51 / 40 20 0 0 20 80
Moses Lake 37 66 42 73 46 62 / 0 0 0 10 50 40
Wenatchee 41 67 46 70 48 60 / 0 0 0 10 50 40
Omak 33 66 39 70 44 60 / 10 0 0 20 50 40

&&

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

$$