Winter Weather Advisory 21, NWS Spokane, WA

Area Forecast Discussion
National Weather Service Spokane WA
232 PM PST Sun Feb 24 2019

.SYNOPSIS...
A moist frontal system will bring continued snow to southeast
Washington into the Central Panhandle Mountains of Idaho this
evening and again on Monday. Moderate snow accumulations are
likely in this area with a chance of light snow elsewhere. Another
system arrives Wednesday or Thursday with a chance of snow.
Temperatures will remain well below normal through the week.

&&

.DISCUSSION...
Tonight through Monday: A positively-tilted trough is dropping
down from British Columbia into the Pacific Northwest today. Of
particular note is an W-E oriented jet streak on the south side of
this trough that is carrying considerable atmospheric moisture
inland. This system's surface low is quickly tracking eastward
across central Oregon, with a relatively narrow plume of snow
slowly drifting northward. As of this writing, the northern fringe
is nearing the Interstate 90 corridor. All told with this system,
a few inches of snow were evident along the east slopes of the
Cascades, and a couple of inches possible along the Palouse
southward toward the Lewis-Clark Valley, Blue Mountains, and Camas
Prairie. Additionally, breezy northeast winds with gusts of 20-30
mph are expected across the northern ID Panhandle, Palouse, and
Columbia Basin with reports of localized blowing and drifting snow
this afternoon.

A brief respite is expected tonight in between storm systems.
With clearing skies and cold advection winds, much of the forecast
area is projected to drop down into the single digits and lower
teens tonight.

The next wave then reloads, first impacting SE Washington and the
central ID Panhandle early Monday morning and slowly lifting
northward through the day. This feature looks to be a bit stronger
and wetter than today's, and winter weather highlights have been
issued to address this. This system's northward track will again
be limited by drier, gusty northeast winds across the northern
portions of our forecast area. These gusty northeast winds will
likely cause some patchy blowing and drifting snow Monday
afternoon and night in similar wind-prone areas. Energy with this
system will begin to move eastward Monday night into Tuesday
morning.
Dang

Tuesday through Thursday night...The cold pattern continues with
continued upper ridging in the eastern Pacific and a cold upper
trough over the Inland NW. On Tuesday one system exits with
lingering show showers mainly over the Idaho Panhandle. The next
system in the form of a closed low off the WA/OR coast will send
another shot of moisture into the area but models showing
significant timing differences as well as placement of highest
snowfall. The GFS and the GEFS once again favor SE Washington into
the Central Panhandle Mountains both Wednesday and Thursday while
the ECMWF and Canadian show a more widespread light to moderate
snow over the region Wednesday shifting into the Idaho Panhandle
Thursday. With the National Blend of Models supporting more of a
ECMWF/Canadian solution the forecast leans this way but confidence
is low. Given the uncertainty mainly chance POP's were utilized
for Wednesday and Thursday. With the low off the coast and cold
arctic air over southern BC and along the Rocky Mountain Divide
north to northeast winds will continue with breezy conditions at
times. These winds will continue to usher cold air into the region
with highs in the mid 20s to lower 30s for most towns with lows
in the single digits and teens. These values are about 15 to 20
degrees below normal. JW

Friday through Sunday...
It looks like the tail end of snow will be moving through the
Idaho Panhandle by the end of the day Friday. Following, we may
get a break from the snow this weekend with drier weather.
However, it doesn't look like it's going to be warming up soon.
The below-normal temperatures will continue into the weekend with
the north- northwesterly flow bringing the cold air from Alaska.
The highs will remain in the mid-20s to mid-30s & lows in the
teens.
JAS

&&

.AVIATION...
18Z TAFS: An east-west oriented storm system is currently moving
through the region. At this hour, snow is bringing IFR conditions
to KPUW-KLWS-KEAT, and will likely continue through around 00z
before dissipating. KGEG-KSFF-KCOE-KMWH will be on the northern
fringe of this system, and VFR conditions may briefly deteriorate
to MVFR this afternoon. The next round of snow will likely start
impacting KPUW-KLWS around or after 12z tonight. Anything which
falls will be quite light and fluffy and subject to some blowing
as N-NE winds increase through the day.
Dang

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        11  22  10  24  10  26 /  10  50  40  10  20  50
Coeur d'Alene  10  22  10  24  10  26 /  10  50  50  10  20  50
Pullman        18  24  12  24  13  26 /  60  70  70  20  40  50
Lewiston       26  30  20  30  21  32 /  30  80  70  20  40  50
Colville        7  32   8  31   6  34 /   0  30  20   0  20  40
Sandpoint      10  21  11  23  11  26 /   0  40  40  20  20  50
Kellogg        12  20  11  23   9  26 /  40  70  60  30  40  60
Moses Lake     16  28  13  27  14  29 /   0  50  30  10  20  40
Wenatchee      16  26  14  25  13  27 /  20  50  30  10  20  40
Omak           14  28  14  28  13  29 /   0  30  20   0  20  40

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory from 10 AM Monday to 4 AM PST Tuesday
     for Central Panhandle Mountains.

     Winter Storm Warning from 4 AM Monday to 4 AM PST Tuesday for
     Lewis and Southern Nez Perce Counties.

     Winter Weather Advisory from 4 AM Monday to 4 AM PST Tuesday for
     Lewiston Area.

     Winter Weather Advisory from 7 AM Monday to 4 AM PST Tuesday for
     Idaho Palouse.

WA...Winter Weather Advisory from 4 AM Monday to 4 AM PST Tuesday for
     Lower Garfield and Asotin Counties.

     Winter Weather Advisory from 7 AM Monday to 4 AM PST Tuesday for
     Washington Palouse.

     Winter Weather Advisory from 4 AM Monday to 4 AM PST Tuesday for
     Northeast Blue Mountains.

&&

Hazardous Weather Outlook
National Weather Service Spokane WA
621 AM PST Sun Feb 24 2019

IDZ001-002-WAZ034>038-043-044-251430-
Northern Panhandle-Coeur d'Alene Area-Moses Lake Area-
Upper Columbia Basin-Spokane Area-Northeast Mountains-
Okanogan Highlands-Okanogan Valley-Waterville Plateau-
621 AM PST Sun Feb 24 2019

This Hazardous Weather Outlook is for portions of North Idaho...
Central Washington...East Central Washington...North Central
Washington and Northeast Washington.

.DAY ONE...TODAY AND TONIGHT

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A storm system will give a glancing blow to this area on Monday
and Tuesday and could result in moderate snow for most locations
aside from the Okanogan Highland and Okanogan Valley. Unsettled
weather will continue at times through Thursday with more light
snow possible. Temperatures should remain well below the seasonal
normals for this time of year.

IDZ003-004-026-027-WAZ031>033-251430-
Idaho Palouse-Central Panhandle Mountains-Lewiston Area-
Lewis and Southern Nez Perce Counties-Northeast Blue Mountains-
Lower Garfield and Asotin Counties-Washington Palouse-
621 AM PST Sun Feb 24 2019

This Hazardous Weather Outlook is for portions of North Idaho...
North Central Idaho and Southeast Washington.

.DAY ONE...TODAY AND TONIGHT
Widespread light snow is expected to fall today across much of the
area.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A stronger winter storm will pass through this area on Monday into
early Tuesday which will likely deliver periods of moderate to
locally heavy snow. Unsettled weather will then continue through
Thursday with light snow possible. Temperatures should remain
well below the seasonal normals for this time of year.

WAZ041-042-251430-
Wenatchee Area-East Slopes Northern Cascades-
621 AM PST Sun Feb 24 2019

This Hazardous Weather Outlook is for portions of North Central
Washington.

.DAY ONE...TODAY AND TONIGHT

Widespread light to moderate snow is expected to occur through
this morning across this area. The greatest risk of significant
snow will occur south of Lake Chelan.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

Periods of light snow are expected to continue at times through
Thursday. Meanwhile temperatures are expected to remain much
colder than normal for this time of year.