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Area forecast discussion 
National Weather Service Spokane Washington
426 am PST sun Jan 25 2015

Synopsis...
more fog and low clouds are expected today as high pressure
returns. Record high temperatures will be possible both today and
Monday across southeast Washington and the Idaho Panhandle. A
weak storm system will affect the area mid- week...increasing the
threat of light valley rain and mountain snow. A ridge of high
pressure will then rebound late in the week for drier weather and
more fog.



&&

Discussion...

Today through Mon nt: the main challenges for today and Mon will
be fog and/or the areal coverage of stratus...as well as the
possibility of record high temps. Much of ern WA and north Idaho
remain under a canopy of low clouds and areas of fog. Concerning
the dense fog advisory for this morning... we expect vsbys to
fall once again to below one half mile once the thick mid cloud
deck over the advsy area exits east. This will be our number one
priority and we'll adjust the fcst as needed. Rapid height rises
aloft accompanying a quickly strengthening upper ridge today will
lead to a dry fcst and, as lower tropospheric temps warm
considerably, those sites that mix (non- Deep Valley sites) will
likely see record or near record high temps across southeast Washington
and adjacent parts of north Idaho. Monday should see similar
to slightly cooler temps as the warm temps aloft cool slightly
as the upper ridge weakens. Towns close to the Cascades and in
the nrn WA valleys likely won't mix and could remain under fog
and/or low clouds a good part of the day. Bz

Tuesday through saturday: a strong ridge of high pressure will
dominate the region. Models do show a weak cold front topping over
the ridge Tuesday and Tuesday night. This may result in some light
precip in the form of rain and High Mountain snow, but this
feature weakens considerably as it pushes into the ridge. Will
continue to leave some low chance precip chances in the mountains
and in the Idaho Panhandle. The main affect that this front will have
will to cool the low to mid levels of the atmosphere off and
weaken the surface inversion. This may be enough to break up the
low clouds and fog across the region on Tuesday and Wednesday.
This will also bring an end to the abnormally warm temps across
portions of the region that have not been stuck under the low
clouds.

The trend after mid week will be for the ridge to re-establish
itself over the region. Models do show another shortwave
disturbance (even weaker than on tuesday) pushing through the
ridge on Thursday. Will keep a small chance of precip in the
mountains for this wave, but should otherwise brush by without
notice. Models then diverge a bit with how strong the ridge will
become heading into next weekend. The European model (ecmwf) and the Canadian
models have shown a more amplified longwave pressure pattern with
the ridge building further in. The Canadian model places the axis
of the ridge more offshore and places the inland northwest in a
colder northernly flow pattern. The ECMWF, on the other hand,
places the ridge squarely over the region and pushes moisture off
of the Pacific further north into British Columbia. The GFS solution is a bit
flatter and would present the best possibility for precip (mainly
across the northern zones) with an atmospheric river setting up
into southern British Columbia. The forecast was trended between the 12z GFS and
European model (ecmwf) guidance, but confidence is low due to high model
uncertainty. /Svh

&&

Aviation...
12z tafs: we've improved the vsbys for the Spokane/ c'da area
tafs into the MVFR category but kept ceilings as low as IFR as an
extensive mid-cloud deck has remained over area and limited
cooling. However...there still are pockets of LIFR vsbys generally
north of Spokane where snowmelt from warm temps has significantly
contributed to the fog threat. This includes the Deer Park
Airport. Kpuw and klws will remain VFR and dry...with southeast winds at
kpuw 10-13kt. LIFR vsbys will be more common for the kmwh and keat
taf sites as skies remain clear west of the aforementioned mid
cloud deck this morning.

&&

Preliminary point temps/pops...
Spokane 47 35 46 35 44 33 / 0 0 0 0 0 10
Coeur D'Alene 47 33 47 33 45 34 / 0 0 0 0 0 20
Pullman 55 40 55 38 51 37 / 0 0 0 0 0 20
Lewiston 58 40 58 39 53 39 / 0 0 0 0 0 10
Colville 44 30 43 27 41 30 / 0 0 0 0 10 10
Sandpoint 44 31 46 31 45 33 / 10 0 0 0 10 20
Kellogg 46 34 48 33 48 34 / 10 0 0 0 0 20
Moses Lake 47 35 46 32 45 33 / 0 0 0 0 0 10
Wenatchee 45 33 46 30 44 33 / 0 10 10 10 10 10
Omak 42 34 40 30 37 31 / 0 10 10 10 10 10

&&

Otx watches/warnings/advisories...
Idaho...none.
Washington...dense fog advisory until 1 PM PST this afternoon for northeast
mountains-Okanogan Highlands.

&&

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