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Area forecast discussion 
National Weather Service Spokane Washington
246 PM PST sun Feb 14 2016

Synopsis...
mild air will spread over the inland northwest early this week as
periods of rain occur over the mountains. Tonight into Monday will
be quite windy with portions of eastern Washington experiencing
wind gusts to 40 mph. High temperatures on Monday, Tuesday, and
Wednesday will reach the 50s in many locations. We will likely see
a return to breezy and wet weather Thursday and Friday with the
potential for drier weather next weekend.

&&

Discussion...

..windy overnight into Monday morning southeast Washington and
Cascades...

Tonight into monday: a strong warm front will surge northward
tonight bringing rising snow levels, mild air, locally heavy rain,
and gusty winds to the inland northwest. Gusty winds will be our
main concern, and wind advisories have been issued for the Palouse
and Pomeroy areas for sustained winds of 25 to 30 mph with gusts
to 45 mph. A Wind Advisory has also been issued for Wenatchee,
Chelan, and Waterville Plateau for the potential of localized wind
gusts of 45 mph or more.

Neither of the wind advisories are a slam dunk. Southeast
Washington and the Idaho Palouse will get windy overnight, but
could fall a bit short of advisory criteria. The southwest surface
pressure gradient and 850mb winds will peak between 3 am and 10 am
which is not the best time of day for optimum mixing. However, our
air mass will be unseasonably mild tonight leading to weak low
level inversions. Given the time of day, elevations above 2500ft
may have the best shot of gusts to 45 mph.

Wenatchee, Chelan, and Waterville Plateau have the potential for
mountain wave gusts during the early morning hours. This pattern
has produced strong winds in the past. A flat upper level ridge, a
strong upper level jet core along or just north of the Canadian
border, a pronounced mid-level inversion about 4000-6000ft
elevation, and strong westerly winds near the mid-level inversion
are all ingredients that have produced localized gusts east of the
Cascades in the past. Our skill in forecasting mountain waves
isn't particularly high, but even a small chance of gusts in the
40 to 60 mph range should probably be highlighted. If our weak low
level inversion holds, Wenatchee may not experience any winds more
than 15 mph.

Monday's temperatures will be a good 10 to 15 degrees above
average. Breezy and cloudy conditions tonight will assure a mild
morning and the Columbia Basin will have a good shot of some
sunshine during the day Monday. Precipitation will mainly be
limited to the mountains, but north Idaho and northeast Washington
may experience periods of light rain throughout the day as
remnants of a weak front linger along the Canadian border. /Gkoch

Tuesday through thursday: a moist westerly flow will continue
with a persistent frontal boundary that will waiver up and down
across the region through midweek. This frontal boundary will
continue its sag southward on Tuesday, spanning across southern
sections of the forecast area or roughly from the central Cascades
to the central and southern Idaho Panhandle. Both the GFS and NAM
show quite a bit of rain shadowing with this boundary given the
amount of low level west-southwest winds. Will indicate the best
chance of precipitation across the mountains. Snow levels will
continue to be quite high, roughly 5-6k ft which will give only
the higher elevations any accumulating snow. Mild daytime
temperatures will return on Tuesday with just slight changes from
Monday. By Tuesday night, the frontal boundary will begin to lift
northward with another surge of warm air advection. This will
bring another wave of precipitation to the northern mountains
overnight as low level winds back to the south overnight with more
mild overnight temperatures. For Wednesday, the warm front will
stretch across the Canadian border, leaving much of the forecast
area residing in the warm sector with mild temperatures and
continued southerly flow. Anticipate a persistence in mild
temperatures and high snow levels. A surface low in the eastern
Pacific will creep closer the Washington/or coast. Instability will
increase by afternoon especially across The Highlands of eastern
or and pressing into the southern Idaho Panhandle and southern Washington
Cascades. Could see some convection in the higher terrain
Wednesday afternoon and evening. Meanwhile, a cold front will move
through western Washington and cross the Cascades Wednesday night
as shower activity increases. Then Thursday and into Thursday
night, the initial cold front plows across the region and weakens
into northwest Montana. Snow levels will lower to 4-5k ft behind the front
with a good swath of precipitation across much of the region.
Better instability across the central Washington Cascades and central
Panhandle mountains will a few hundreds of cape along with the
passage of an upper level shortwave, which may lead to some
isolated graupel showers. The chance of showers decreases
overnight.

Impacts for mid week:

Mountain snow: snow levels will be quite high Tuesday and Wednesday
with only the higher elevations near the Cascade crest and the
Panhandle mountains seeing any accumulation. Snow levels will
lower by Thursday with light to moderate mountain snow possible.

Hydro concerns: the prolonged period of mild temperatures and high
snow levels will help the melting of the current mountain snow
pack and sheltered lower elevations. This may lead to continued
rises on area streams/creeks and ponding of water in fields and
low lying areas. /Rfox.

Thursday night through sunday: the inland northwest remains in a
progressive pattern with continued rain and mainly mountain snow
chances, until a ridge starts in next weekend to dry things out.
Temperatures will undergo slight cooling into the end of the week,
though values still remain above seasonal norms.

* Timing/evolution: first on Thursday night one system pulls
east. Precipitation chances will continue in the Cascades,
eastern mountains and the far southeastern County Warning Area in the moist
west- northwest upslope flow. Second between Friday and Friday
night the next system, an occluding frontal wave, pushes in with
good precipitation chances. Some models are quicker and/or
indicate more overrunning precipitation expanding in Friday
afternoon than others, before the precipitation with the
occluding front pushes in late Friday into Friday night. So
while chances are high that the system will bring precipitation,
confidence in timing is only fair. Still overall chances will be
on the rise into late Friday. Saturday the front starts east and
the steadier precipitation threat retreats to the mountains,
while more hit-and-miss shower chances linger over the eastern
Columbia Basin rises. Between Saturday night and Sunday the
ridge builds in and further reduces the precipitation chances.
Mainly slight chances will linger around the mountains. To be
monitored, however, is some models bring the next plume of
moisture closer to the Cascades by late Sunday. This could mean
higher precipitation chances toward the west/northwest County Warning Area by
late next weekend. That solution remains the outlier but we will
watch for any signs that other models are trending in that way.
Another things to watch for late in the weekend will be some
patchy fog, especially in the sheltered mountain valleys.

* Snow levels/precipitation-type: through Friday snow levels
generally range between 2500 to 3500 feet, lowest near the
Cascade Valley. Snow levels dip a bit more Friday night into
Saturday morning, which could allow a rain/snow mix or all snow
even in the some of the valleys, especially along and north of
I-90. However if there any snow impacts it would more likely be
through the mountain passes.

* Winds: as Thursday night's system shifts east another secondary
low develops over southern ab/northwest Montana. The tightening
pressure gradient with that feature and at least a modest low
level jet surging north through the Columbia Basin ahead of
Friday system will make for some breezy to windy conditions
Thursday night to Friday night. Right now there looks to be
somewhat of a lull going into Friday morning, before things pick
up again. At this times general speeds are forecast in the 10 to
20 mph range with gusts near 30 mph, except in the more
sheltered terrain. Since it is still several days away, the
details are likely to be adjusted, including potentially
stronger winds near the Blue Mountains Thursday night but models
have not be consistent on the point. Winds slowly abate into the
weekend. /J. Cote'



&&

Aviation...
18z tafs: a band of broken band of light precipitation is
expected to produce a couple hundredths rain this afternoon and
evening in Spokane, Coeur D'Alene, Pullman, and Lewiston. Ceilings
in the 800 to 2000 ft range are expected to accompany the light
rain through the evening. The arrival of a warm front overnight
will bring the potential for low level wind shear to Spokane,
Coeur D'Alene, and Pullman. The increasing surface pressure
gradient should cause strong winds to reach the surface in the
09z-12z time frame creating gusts in the 30-35kt range into Monday
morning for the aforementioned airports. The wind forecast for
Wenatchee is tough. Many times, strong cold fronts in the winter
fail to bring winds to the surface, but our mild air mass and
weaker inversion may promote gusts of 25kts or more during the
early morning hours. For now, the Wenatchee taf has several hours
of low level wind shear, but surface gusts may need to be added.
/Gkoch




&&

Preliminary point temps/pops...
Spokane 44 53 43 52 40 51 / 30 30 10 20 30 10
Coeur D'Alene 42 51 41 51 39 50 / 70 60 20 30 40 20
Pullman 46 56 43 54 41 54 / 60 30 10 40 30 30
Lewiston 49 63 42 60 43 58 / 60 10 0 30 10 20
Colville 39 50 37 51 39 48 / 40 40 40 20 40 30
Sandpoint 39 47 38 48 37 46 / 90 80 60 50 50 30
Kellogg 40 46 39 45 39 46 / 100 100 60 80 40 30
Moses Lake 44 60 44 57 42 53 / 0 0 0 0 10 10
Wenatchee 40 58 38 54 39 46 / 10 10 0 0 10 40
Omak 36 52 34 49 37 45 / 10 10 20 10 10 40

&&

Otx watches/warnings/advisories...
Idaho...Wind Advisory from 2 am to noon PST Monday for Idaho Palouse.

Washington...Wind Advisory from 2 am to noon PST Monday for lower Garfield
and Asotin counties-Washington Palouse.

Wind Advisory from 1 am to 8 am PST Monday for Waterville
Plateau-Wenatchee area.

&&

$$

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