Area Forecast Discussion
Issued by NWS Spokane, WA

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FXUS66 KOTX 271757
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
957 AM PST Fri Jan 27 2023

.SYNOPSIS...
A frontal system Friday and Saturday will bring a mix of rain and
snow to the valleys of north Idaho and northeast Washington with
locally heavy snow accumulations to the Idaho Panhandle
mountains. Blustery northeast winds will usher an Arctic air mass
into the region Saturday and Sunday. Temperatures will be well
below average through the middle of next week with highs in the
teens and low 20s and morning lows in the teens and single digits.

&&

.DISCUSSION...

Today through Saturday: Temperatures have remained more mild
through the night than previously forecast resulting in much of
the precipitation falling as rain or non-accumulating snow in most
valley locations. The northwest to southeast orientation of this
shortwave moving through also is not generating as much
precipitation over northeast Washington as previously expected. As
such, the snow forecast as been drastically reduced for the
Northeast Mountains, Spokane/Coeur d`Alene corridor, and the
Washington Palouse. I do not expect there to be much if any snow
accumulations for these areas through the rest of this morning,
except for possibly a little slush for colder pockets and higher
benches such as the West Plains and South Hill. The winter weather
advisory has been cancelled for these areas. I have also modified
the winter weather advisory in the Northern Panhandle to the
Coeur d`Alene area to those above 2500 feet in elevation as
downtown Coeur d`Alene, Sandpoint, and Bonners Ferry all are
reading temperatures at 34 to 36 degrees with rain or non-
accumulating snow being reported. The higher elevations above 2500
feet will see the potential for 1 to 3 inches of snow
accumulation through the rest of this morning making for slippery
travel during the morning commute period. I-90 through Spokane and
Coeur d`Alene will very likely just remain wet with little to no
impacts expected during the morning commute. Heaviest snow is
still expected to be in the Central Panhandle Mountains where
westerly flow ahead of the shortwave will result in good
orographic lift with winter travel expected from 4th of July Pass
eastward through the Silver Valley and over Lookout Pass. The
winter storm warning remains in effect along with winter weather
advisories that include the Idaho Palouse, Northeast Blue
Mountains and the Camas Prairie.

Precipitation will shift into southeast Washington and into the
Idaho Panhandle by this afternoon. Then we will be watching as
the Arctic Boundary pushes in Friday night. Looks like the Arctic
boundary doesn`t move into the Northern Panhandle until after
midnight. It will then sweep southwestward across the region
through the night with snow showers expected to develop along the
boundary. These snow showers don`t look to be significant, but
temperature profiles will be getting colder by then with high
confidence that precipitation will fall as snow. Mid levels become
more unstable especially over the Northern Panhandle with a quick
burst of a half an inch to an inch of snow possible. The greater
impact looks to be the increasing northeast winds that will
develop with the Arctic boundary and the cold modified Arctic air
that will accompany these winds. Wind gusts of 30-40 mph will be
possible down the Purcell Trench and out over the northern
Columbia Basin on Saturday. I would`t be surprised if we see some
wind gusts getting close to 45 mph as those winds increase through
the afternoon on Saturday. Winds don`t look to get strong enough
with enough widespread sustained winds of 30 mph and gusts to 45
mph to necessitate an wind advisory. Small branches may break
where the stronger winds develop down the Purcell Trench and could
see a few power outages. Temperatures will have a hard time
warming up with the Arctic pushing in on Saturday with highs only
expected to warm up into the low to mid 20s over northeast
Washington and the Northern Panhandle and the upper 20s to low 30s
over the basin. /SVH

Saturday night through Thursday:  Cold and dry northeast wind
continues allowing for cold and dry conditions to linger on.
Sunday night/Monday morning likely being the coldest portion of
the seven day forecast with some slow gradual moderation after but
until then the wind combined with the very cold temperatures will
make for very cold wind chill values. The upper level ridge
reorients to allow a more northwest rather than north/northeast
flow on Tuesday and a minor wave or two to approach from there
thus minor pops for snow showers start to show up over the Cascade
Crest and portions of North Idaho as early as Tuesday/Tuesday
night and shows a gradual expansion and increase in pops, sky, and
temperature. /Pelatti

&&

.AVIATION...
18Z TAFs: Showers will linger around KPUW/KLWS during the late
morning, but most other TAF locations will remain dry for the
remainder of today. An Arctic boundary will drop out of Canada
overnight. This will switch winds out of the northeast and bring
snow showers along its boundary, mainly across northern ID. These
northeasterly winds are likely to be gusty during the daylight
hours Saturday, and chances for snow are expected to expand beyond
just N Idaho and into E Washington after 12Z Saturday. /KD

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        37  22  27   7  18   4 /  20  30  20   0   0   0
Coeur d`Alene  37  21  26   4  17  -1 /  30  50  20   0   0   0
Pullman        39  27  30   7  18   4 / 100  30  30  10   0   0
Lewiston       47  32  36  13  24   8 /  90  20  40  10   0   0
Colville       39  22  27   2  19   0 /   0  40  30   0   0   0
Sandpoint      37  20  24   6  16   2 /  30  80  30   0   0   0
Kellogg        36  18  24   2  13  -3 /  80  80  40   0   0   0
Moses Lake     45  26  33  15  25   9 /  10   0  20   0   0   0
Wenatchee      42  27  31  13  21   8 /   0   0  20   0   0   0
Omak           38  23  30  11  20   5 /   0   0  30   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until noon PST today for Coeur d`Alene
     Area.

     Winter Weather Advisory until noon PST today for Idaho Palouse.

     Winter Storm Warning until 4 PM PST Saturday for Central
     Panhandle Mountains.

     Winter Weather Advisory until 7 PM PST this evening for Lewis
     and Southern Nez Perce Counties.

WA...Winter Weather Advisory until 7 PM PST this evening for
     Northeast Blue Mountains.

&&

$$


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