Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 191156
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
356 AM PST Sun Jan 19 2020

.SYNOPSIS...

Bands of light precipitation, mainly snow, will persist over the
Idaho Panhandle and northeast Washington overnight. The majority
of the Inland Northwest will be dry Sunday and Monday with
afternoon temperatures in the 30s. Our next opportunity for
widespread precipitation will be Tuesday. The remainder of next
week looks mild for mid January with chances for light rain and
snow.

&&

.DISCUSSION...

Today: A threat for light precipitation will continue through the
day today with weak isentropic ascent. Best chances for
precipitation will across the northern mountains down into the
northern basin. Easterly winds off of the higher terrain in the
Central Panhandle is expected to dry out the boundary layer that
precipitation there is less of a threat, and that drier air
should extend out across Ritzville to Moses Lake. Precipitation
type this morning will predominantly be as snow, but can`t rule
out some pockets of freezing. The freezing rain threat looks to be
fairly isolated and didn`t include it in the forecast. Lift will
be so weak that little accumulating snow is expected. That said,
added moisture on the roads with temperatures near freezing may
result in a few slick spots before road temperatures warm up later
in the morning. That drier air will push further north through
the afternoon with the light precipitation mostly confined to the
east slopes of the northern Cascades and near the Canadian border
by early evening.

Sunday night through Monday night: This period will be dry and
rather benign. There will be a threat for patchy fog, but I think
much of the moisture in the boundary will condense as low stratus
rather than widespread fog. Temperatures will continue to moderate
though with temperatures slightly above normal values for mid
January. /SVH

Tuesday and Tuesday Night: A trough will move through the region.
Most locations will see some light precipitation. The exception
will be around the Moses Lake area. Snow will move over the
Cascades during the morning and spread into the
Wenatchee/Waterville Plateau and Okanogan Valley. There will be
upslope flow into the Cascades during the morning, so this will be
the best chance to see accumulating snow. By the afternoon the
flow turns westerly becoming more of a Cascade crest snow event.
During the afternoon the precip will move will move into eastern
WA and north ID. Snow levels will rise, with most of the valleys
seeing a rain or rain/snow mix. By the evening and overnight hours
central WA dries out with a chance of light precip elsewhere. Snow
amounts south of I90 will be little to none. The best area for light
snow will be the east slopes with the valleys seeing 1-3 inches
and the mountains seeing 5 to 10 inches.

Wednesday through Saturday: The trough exits to our east early
Wednesday as a ridge builds over the western US through Thursday.
The ridge gets pushed eastward Friday as westerly flow/a weak
trough moves into the region.

Wednesday morning will be fairly quiet with the best chance of
precip falling along the Cascade crest and the ID Panhandle. There
are some discrepancies in the strength of the warm front moving up
from the south Wed afternoon. Looks like the EC and Canadian are
stronger with bringing the warm air north into Spokane, while the
GFS is quite a bit slower and not as warm. Looking at the ensemble
clusters, the GFS solution and its ensembles are the cold
outliers. There are also differences in precip chances, with the
GFS being pretty dry Wed and Thur, meanwhile the EC/Canadian is
showing light to moderate precip, which matches better with the
NBM. Fri and Sat we will continue to see unsettled weather with
the best chance being across the mountains and higher elevations.

Temperatures will continue to slowly warm. Thursday morning onward
some lower elevation locations will remain above freezing through
Sat. With temps moderating across the Columbia Basin/LC
Valley/Palouse into the Spokane/CDA area and even the northern
valleys...we will see rain with maybe a rain/snow mix at times. /Nisbet

&&

.AVIATION...
12Z TAFS: Moist upslope flow into the Spokane/Coeur d`Alene
corridor will produce very light snow showers through the morning.
Snow is not expected to accumulate much but may result in slick
runways/taxiways with surface temperatures at or near freezing.
Snow showers will also develop further northward across airfields
from the east slopes of the northern Cascades to the Northeast
Mountains and Northern Panhandle. A moist boundary layer across
the northern portions of the basin and into the mountain valleys
will result in a lot of low stratus and MVFR/IFR conditions
including at: KGEG, KSFF, KCOE, KEAT and KMWH. Improvements are
expected as drier air filters in off of the Panhandle from the
southeast. This drier air is not expected to make it as far as
Wenatchee, however, with MVFR conditions expected through Sunday
night. /SVH

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        38  30  39  29  39  31 /  20   0   0   0  70  20
Coeur d`Alene  40  31  40  30  40  34 /  20   0   0   0  80  30
Pullman        38  32  39  33  39  31 /   0   0   0   0  60  20
Lewiston       42  34  43  36  44  35 /   0   0   0   0  50  30
Colville       38  29  40  27  40  30 /  30  10   0  10  70  20
Sandpoint      38  31  38  31  39  35 /  40   0   0   0  90  70
Kellogg        41  31  42  32  41  34 /  20   0   0   0  90  60
Moses Lake     38  30  38  29  40  29 /  10   0   0  10  40  10
Wenatchee      35  30  37  29  36  27 /  20   0   0  20  60  20
Omak           34  29  37  29  37  28 /  30  20   0  10  60  20

&&

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

&&

$$


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