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Area forecast discussion 
National Weather Service Spokane Washington
428 am PDT Monday Apr 27 2015

Synopsis...
high pressure will build into the region today and linger through
Tuesday for a couple of days of nice weather. Between Tuesday
night and Thursday a weather disturbance will bring more seasonal
temperatures, breezy conditions and a threat of showers, followed
by a general drying trend by the weekend.



&&

Discussion...

Today through Tuesday...narrow and slightly positively tilted
ridge of high pressure amplifies into the region allowing for a
continuation of the warming and drying trend with temperatures
peaking on Tuesday. Forecast temperatures are well above normal
Tuesday. A quick look at climo records show that most record high
temperatures for Tuesday are in the 80s and 90s so no sites are
expected to be near record highs, at least at this point in time.
/Pelatti

Tuesday night through Wednesday night...an upper level trough will
track through the Pacific northwest during this time frame. Some minor
timing issues but it looks like the associated cold front will
move across the Cascades late Tuesday evening then track quickly
east and be along the Idaho/Montana border right around mid-day Wednesday.
Model guidance is similar showing a brief increase in moisture
with the frontal passage. This will lead to a very good chance
for showers and breezy/gusty winds with the front. The NAM and to
a lesser extent the GFS models are showing a pretty decent
increase in mid and upper level instability with fropa. Forcing
with the front should be quite adequate to lift parcels into this
unstable layer. I went ahead and pushed the timing of the
thunderstorms to coincide with the front between 06z-18z. While
the atmosphere will remain unstable through sunset Wednesday
evening it looks like surfaced based convection Wednesday
afternoon will not be deep enough to support anything more than
showers. Temperatures will take about a 8-12 degree drop putting
temperatures back near normal. Surface pressure gradients will
increase to 10-12mb with 850mb winds between 20-30kts. These winds
should be able to mix down to the surface with and behind the cold
front. With the front coming through at night winds may not reach
the same velocities if it came through during the day. But still
breezy/gusty winds will be common east of the Cascades overnight
and through the morning hours, before decreasing in the
afternoon.

Thursday through Monday the upper pattern will be zonal (west-east
winds) with what looks like a few weak waves moving through b.C at
times. Breezy winds and showers, mainly near the Cascade crest and
along the higher terrain of the northern and Panhandle mountains
will be possible with each of the aforementioned waves. Hard to
pinpoint the exact timing right now. Temperatures will be near or
on the warm side of normal through the weekend. Tobin



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Aviation...
12z tafs: a ridge of high pressure building over the aviation area
will allow VFR conditions to prevail for the next 24 hours. Minor
exception will be this morning in some of the valleys north of
kgeg to ksff to kcoe line where areas of morning fog may bring
LIFR ceilings and visibilities at times between 12z-18z Monday.
/Pelatti

&&

Preliminary point temps/pops...
Spokane 66 45 75 45 62 39 / 0 0 10 30 20 10
Coeur D'Alene 67 40 75 41 62 36 / 0 0 10 30 30 10
Pullman 66 41 73 41 60 37 / 0 0 0 20 30 10
Lewiston 72 45 82 48 67 42 / 0 0 0 20 20 10
Colville 70 41 77 46 66 39 / 0 0 10 60 20 20
Sandpoint 67 36 74 40 61 35 / 0 0 10 30 40 20
Kellogg 65 39 72 41 59 36 / 0 0 0 30 40 20
Moses Lake 72 44 78 41 67 39 / 0 0 0 20 10 10
Wenatchee 74 50 74 44 67 43 / 0 0 0 10 10 10
Omak 72 43 76 41 67 37 / 0 0 10 10 10 10

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

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