Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 221159
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
359 AM PST Wed Jan 22 2020

.SYNOPSIS...

A mild and active weather pattern is expected into next week with
several rounds of mainly valley rain and mountain snow.

&&

.DISCUSSION...
Today through Thursday: The upper trough that brought rain and
snow to the region on Tuesday has exited the area while a warmer
and wetter system is approaching off the coast. Most of the region
will see a break this morning between systems except for post
frontal showers into the Idaho Panhandle and Cascade crest. Patchy
freezing fog will also continue through at least early morning
around Wenatchee and Ephrata. For late this afternoon into
Thursday a moist southwest flow develops with a warm front
providing isentropic ascent over the region. This will result in
widespread precipitation first over Central WA this afternoon
spreading into Eastern Washington and north Idaho by early this
evening. Cold air trapped along the East Slopes of the Cascades
should result in precipitation starting as snow. The Wenatchee
area and Okanogan Valley are a tougher call with highs in the mid
to upper 30s more likely to result in a rain/snow mix with little
to no accumulation. As precipitation reaches Eastern WA/N Idaho
surface temperatures in the mid 30s is expected to result in rain
or rain/snow mix as the prevalent precipitation type in the
valleys with little to no snow accumulation.

For tonight into Thursday morning snow levels rise from south to
north reaching 4000 feet near the Canadian border by afternoon and
6000 feet over the Central Cascades and SE Washington. Light to
moderate snow accumulations are expected in the mountains prior to
the rising snow levels. As the snow levels come up models show
the potential for some lingering valley cold pockets along the
East Slopes of the Cascades through early Thursday morning. Thus
pockets of freezing rain are possible although marginal
temperatures in the low 30s should limit the icing potential. But
given the added snow expected for the East Slopes along with the
freezing rain threat will be extending the winter weather advisory
through 7 AM Thursday. JW

Thursday night through Friday night: Temperatures remain mild for
late January with elevated snow levels for Thursday night into
Friday as an atmospheric river spreads precipitation across the
region with strong isentropic lift. The threat of freezing
precipitation looks to be wiped out with mild air filtering into
the sheltered northern valleys and snow levels 4500 ft near the
Canadian border to 6K ft south. Best snow accumulations will lie
over the northern Cascades and then in the higher peaks of the
Selkirks. A shortwave trough and associated cold front sweeps
through the region on Friday afternoon, bringing a break from the
precipitation and ushering in breezy southwest winds especially
for the Columbia Basin and Palouse region. If the current model
timing holds, the break from precipitation could last for much of
Friday night as temperatures cool in the wake of the front and
patchy freezing fog develop in the sheltered valleys. The latest
rounds of mild temperatures with rain and high mountain snow will
lead to some snowmelt, although current snowpack looks to be able
to absorb the bulk of it. Area rivers should see rises by this
weekend, but the threat of flooding remains low.

Saturday through Tuesday: The active and progressive pattern
continues for the Inland NW through the weekend and into next
week. The upper level flow will become more westerly with a
strong jet guiding a series of Pacific disturbances into the
region. Confidence on the timing of these features is still
lacking, but getting better especially for the weekend with one
weak feature passing through the region Saturday and second
stronger and wetter one for Saturday night into Sunday. More to
come each day through mid week, each bringing a wave of
precipitation. Temperatures and snow levels remain on the warm
side of seasonal levels. Mountains will receive more rounds of
snow, although the precipitation in the valleys will be dependent
on the time of day with a better chance of snow during the
overnight and early morning hours. The 8-14 day outlook continues
to show better chances of above normal temperatures and
precipitations continuing for the rest of the month and even into
early February. /rfox.

&&

.AVIATION...

12Z TAFS: Across NE WA/N Idaho stratus is evident on satellite
imagery but north of KGEG/KSFF as of 12z. The expectation is that
stratus will expand to include KGEG/KSFF based on latest model
guidance but confidence is low. For KEAT/KMWH fog is in close
proximity to these TAF sites but shallow in depth also resulting
in low confidence especially with thickening mid clouds this
morning with an approaching weather system. Rain or a rain/snow
mix is expected to develop from west to east this afternoon/evening
as the next weather system tracks through. JW

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        38  35  43  37  45  35 /  50 100  90  70  80  10
Coeur d`Alene  38  35  41  38  42  35 /  50  90  90  70  90  20
Pullman        39  37  44  38  45  36 /  50  90  80  50  80  10
Lewiston       43  39  46  40  50  38 /  30  60  50  50  70  10
Colville       39  35  39  38  44  34 /  50 100  90  80  80  20
Sandpoint      38  34  39  38  42  35 /  60  90 100  90  90  50
Kellogg        38  34  39  38  42  34 /  70  90 100  60  90  40
Moses Lake     40  37  43  37  51  36 /  80  60  60  80  30  20
Wenatchee      36  33  39  35  44  34 /  70  50  60  80  40  30
Omak           38  34  38  36  42  35 /  60  70  70  70  50  20

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Winter Weather Advisory until 7 AM PST Thursday for East Slopes
     Northern Cascades.


&&

$$


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