Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 211230
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
430 AM PST Sat Jan 21 2017

.SYNOPSIS...
Periods of light snow are expected this weekend over the Inland
Northwest. Our temperatures through the weekend will be relatively
mild with afternoon readings in the 30s and low 40s. A drier and
cooler weather pattern is expected next week with the possibility
of deteriorating air quality as the week wears on.

&&

.DISCUSSION...

Today and Tonight: A ragged band of light precipitation will move
northeastward across the Inland Northwest today. Areas that
receive measureable precipitation should only receive a few
hundredths of an inch. Precipitation will likely fall in the form
of wet snow or a rain/snow mix. With temperatures in the 30s, we
won`t see much accumulation on roadways. The weak, sheared-out
shortwave providing the lift for precipitation today will exit
north Idaho by early this evening. The NAM and GFS are in decent
agreement that another weak shortwave will arrive in central
Washington by early to mid evening and spread into northeast
Washington and north Idaho overnight. Clouds and precipitation
associated with this system will likely keep temperatures from
falling much tonight. We may be dealing with overnight lows in the
low to mid 30s...which is a bit too mild for efficient
accumulation overnight as well.

Sunday and Sunday Night: Temperatures on Sunday have been raised
into the mid and upper 30s for the majority of the Inland
Northwest. An abundance of clouds and light precipitation Saturday
night should inhibit radiational cooling. A relatively mild start
to the day Sunday may influence snow accumulations during the
daytime hours. The NAM, GFS, and ECMWF generate widespread
precipitation amounts between a tenth and a quarter inch on
Sunday. There is enough model omega to suggest that most areas
will receive snow despite the marginally warm surface
temperatures. However, it is tough to determine whether the snow
will have much impact on travel. At this time, the daytime
arrival of the precip with temps in the 30s suggests that we will
add an inch or two accumulation to our snowpack. Well-traveled
roads may become slushy for a few hours, but be wet until sunset
Sunday evening. Places that some clearing Sunday evening could
become slick, but given the abundance of low level moisture many
areas will probably have low clouds. /GKoch

Monday through Wednesday night...An upper ridge will build off the
coast near 130W during this period resulting in a cooler and drier
northerly flow. There are a couple weak disturbances in the
northerly flow that will pass through the Idaho Panhandle bringing
a chance for snow showers but accumulations look very light if
any. A lingering moist boundary layer in the wake of the
Sunday/Sunday night system will result in stratus and patchy fog
for much of next week as the offshore ridge slowly noses towards
the area. Low clouds should limit temperature drops at night with
lows in the upper teens to lower 20s with daytime highs in the
upper 20s to lower 30s. Although the Methow Valley may stay out of
the stratus with single digit lows possible. JW

Thursday and Friday: Model agreement is good that the ridge will
persist over the region well into the extended period, with minor
disturbances only depicted by one model, so consensus is that
we`ll remain dry and cold to end the week. This pattern will set
us up for a typical winter inversion pattern with air quality
issues possibly becoming an issue. For this reason an air quality
coordination call will occur Monday to discuss possible actions.
Freezing fog and low clouds will likely be the only issues through
the end of the week. /bwilliams

&&

.AVIATION...
12Z TAFS: A pair of weak upper level disturbances will bring the
chance for light precipitation to the Inland Northwest. The first
will spread bands of light snow into northeast Washington and
north Idaho during the day. Daytime temperatures in the 30s
combined will inhibit runway accumulations. The second disturbance
will move into central Washington early this evening and into
northeast Washington and north Idaho overnight. At this time, it
does not appear that significant accumulations or visibility
reductions will occur with the shortwave today or tonight. /GKoch

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        39  31  38  28  32  22 /  50  50  70  70  10  20
Coeur d`Alene  38  31  38  28  34  24 /  60  50  60 100  10  30
Pullman        40  33  39  28  33  25 /  40  30  70  50  20  30
Lewiston       42  32  43  31  35  27 /  20  20  50  20  10  20
Colville       35  31  35  27  33  21 /  60  60  40 100  20  20
Sandpoint      38  31  36  30  33  23 /  60  50  20  90  20  20
Kellogg        36  29  35  28  31  24 /  70  30  50 100  20  30
Moses Lake     39  32  38  25  32  19 /  20  50  90  10  10  10
Wenatchee      37  31  37  29  30  21 /  30  80  90  10  10  10
Omak           38  33  37  28  33  19 /  80  60  90  80  10  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$



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