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Area forecast discussion 
National Weather Service Spokane Washington
501 am PDT Friday Oct 9 2015

today will be unseasonably warm with most of the inland northwest
warming into the 70s. Saturday will also be quite warm with breezy
winds developing in the afternoon. A fast moving cold front will
bring a good chance of light rain to the region Saturday night. It
will also be windy Saturday night behind the front. Mild and
mainly dry weather is expected to return for the early to middle
part of next week.



..windy Saturday afternoon into Saturday night....

Today and tonight: an unseasonably warm day is in store for the
inland northwest today. Our region will be under the influence of
deep southerly flow ahead of a strong cold expected to arrive on
Saturday evening. Ahead of the front today, a shortwave high
pressure ridge will amplify over the western U.S. Providing enough
subsidence to bring more sunshine than yesterday. South or
southwest winds in the 10 to 15 mph range will provide enough
mixing to push temperatures into the 70s. Late in the afternoon
and into the evening, a shortwave trough well ahead of the main
cold front will produce rain over the Cascade crest and spread
clouds into north central Washington. The models have trended
drier tonight as this shortwave moves through eastern Washington
and north Idaho, and precipitation chances have been decreased
below 20 percent.

Saturday and sunday: a deep surface low is expected to move inland
on Saturday morning along the central British Columbia coast. A
tight southerly surface pressure gradient will develop by mid day
as the surface low moves through b.C. Into Alberta. Look for
increasingly mild and breezy conditions Saturday afternoon ahead
of the cold front. Rain chances should peak with the passage of
the cold front Saturday evening, and our winds will likely peak
Saturday evening as well. By Sunday, the front will be well east
of the area. Winds should subside as pressure gradients relax
through the day.

* Winds: on Saturday afternoon, sustained south or southwest winds
of 15 to 20 mph will be common over the Columbia Basin, West
Plains, and Palouse with late day gusts to 30 mph. The NAM and
GFS are in good agreement that the cold front will cross the
Cascades during the early to mid evening hours as the surface
low emerges east of the Canadian rockies in central Alberta. The
southwesterly gradient will likely favor the windiest conditions
over the West Plains and upper Columbia Basin in the evening and
spread over the Palouse through the night. The tightest pressure
gradient and best momentum aloft won't arrive until after
sunset, so we may not mix the 40-50kt winds from 850-800mb to
the surface. However, exposed terrain above 2500 feet around
Spokane and Pullman could experience gusts of 45 mph or more
Saturday evening/night. Any convective downdrafts from showers
could produce strong gusts over the Idaho Panhandle as well.

* Blowing dust: the light rain we received on Thursday over the
Columbia Basin, Palouse, and West Plains may limit our blowing
dust potential. Warm temperatures today may dry the soil
somewhat, so we may need to add some dust to the forecast
Saturday evening. Fortunately, the strongest winds will not
arrive until the evening hours. Cooler evening temperatures and
the tendency for humidity to rise overnight should minimize the
impact of blowing dust.

* Precipitation: the strong westerly component of the low/mid-
level winds with the frontal passage will limit precipitation
amounts with this frontal system. The front will also be moving
quickly. The rain shadow east of the Cascades will likely limit
rain amount to a few hundredths for our burn scar areas in
central Washington. The mud slide threat looks very low at this
time. In general, this front will bring a quarter to a half inch
of rain to the Cascade crest with less than a tenth of an inch
elsewhere. The mountains of Shoshone County may be the exception
Saturday night...especially if convective showers develop along
the front.

Sunday night through thursday: next week looks to be relatively
dry and mild. An upper level ridge will rebound across the inland
northwest late Sunday and into Monday, although it will be dirty
with Pacific moisture streaming in as the ridge gradually flattens
aloft. Could see some sprinkles or light precipitation near the
Cascade crest and far northern mountains as a weak warm pushes
north across southern b.C. Temperatures will be mild especially
across the southern portions of the forecast area meanwhile
thickening cloud cover may limit the diurnal heating across the
north. A disturbance will race across southern British Columbia Monday night
into Tuesday and push a weakening cold front across the region.
The flow aloft will continue to flatten. Again mainly light
precipitation is expected across the northern mountains, but
breezy westerly winds will kick up from the Lee of the Cascades
into the Columbia Basin. Drier air will arrive by Tuesday as
temperatures rise slightly. By Wednesday, the upper ridge axis
would have have retrograded into the Pacific near 130w, while
another round of Pacific moisture gets entrainined into the flow.
Expect filtered sunshine to mostly cloudy skies for Wednesday and
Thursday with the increase of high and mid level clouds, although
the chance of precipitation looks meager at this time. The storm
track shifts across southern British Columbia with any activity just brushing
across the Canadian border. Temperatures are forecast to continue
about 5-10 degrees above normal. So expect more dry conditions and
unseasonably mild temperatures for mid October. /Rfox.


12z tafs: patchy fog will be possible through 17z in the sheltered
valleys around Sandpoint, Bonners Ferry, Omak, and Winthrop. A
ragged stratus deck between 2000-3000 feet will be banked against
the Cascades around Wenatchee and Chelan. The stratus should also
dissipate by 18z. Elsewhere VFR conditions are expected for the
next 24 hours under a warm high pressure ridge. /Gkoch


Preliminary point temps/pops...
Spokane 74 55 74 48 64 44 / 0 10 20 60 10 10
Coeur D'Alene 74 53 74 47 64 41 / 0 10 10 60 10 10
Pullman 76 52 76 48 65 40 / 0 0 10 30 10 10
Lewiston 80 56 81 53 72 46 / 0 0 0 30 10 10
Colville 73 50 71 44 64 40 / 0 10 20 70 10 10
Sandpoint 70 51 71 47 65 36 / 0 10 20 70 10 10
Kellogg 74 49 71 46 60 41 / 0 10 10 70 30 10
Moses Lake 73 53 74 47 70 43 / 0 10 10 20 0 10
Wenatchee 70 55 73 48 70 50 / 10 10 20 20 0 10
Omak 70 49 71 43 67 46 / 10 10 40 40 0 10


Otx watches/warnings/advisories...


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