Area Forecast Discussion
Issued by NWS Spokane, WA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
093
FXUS66 KOTX 230012
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
412 PM PST Mon Jan 22 2018

.SYNOPSIS...
An active weather pattern is expected through the week. A wet and
mild weather system will bring significant precipitation Tuesday
into Wednesday and again next weekend with a mix of rain and snow
across the lower elevations and snow in the mountains. Travel
impacts are expected at times, especially over the mountain
passes.


&&

.DISCUSSION...

Tonight through Thursday: A warm moist Pacific system will move
into the region starting Tuesday morning. Snow levels will rise
during the day and overnight hours. Our forecasted low
temperatures Tue night/Wed morning will be near what our high on
Tuesday was. Models have slowed down the timing a bit of the onset
of the precipitation Tuesday morning. Snow will spread across the
Cascades by mid morning and into central WA by late morning. Snow
levels through the aftn will be about 1500-2000 ft for central WA
with snow expected in the Okanogan Valley. The precip will spread
east through the aftn into eastern WA and north ID. Snow levels
will be a bit higher with only rain expected for the Columbia
Basin, Palouse, Spokane/Coeur d`Alene, LC Valley. Precip will
start off as snow in the northern WA and ID valleys and then
transition to rain or a rain/snow mix in the aftn and evening.
Wednesday snow levels will continue to rise with all valleys
seeing rain, except for the Methow valley in the Cascades which
will see continued snow. The trough will start to move inland Wed
night with a cold front passing west to east through the overnight
hours. Thursday showers will continue across most of the region
under the unstable southwest flow.

*Highlights: Have decided to issue warnings across the mountains
 of northern WA and the ID Panhandle. Will issue an advisory for
 the Okanogan Valley as well. These will start Tuesday mid
 morning-early aftn and will end Wed or Thursday depending on the
 timing of the warmer air.

*Impacts: Heavy snow is expected across the mountains. Moderate
 to heavy amounts are expected in the valleys. Generally along and
 north of Highway 20 will see heavier amounts of snow in the
 valleys than areas to the south. Locations that see just rain
 could see around a half an inch to around an inch with this
 system. Rises on areas streams, creeks and rivers is expected,
 especially across the Palouse. /Nisbet

Thursday night through Monday: A post frontal cold and conditionally
unstable airmass resides over Eastern Washington and Northern Idaho
Thursday night and Friday allowing for moderate pops for snow
showers (with a rain/snow shower mix possible during the afternoon
and early evening hours) over the more orographically favored
mountains of North Idaho, Northeast Washington, and within the close
proximity of the lee of the Cascade Crest. Over the weekend and into
the early portion of the next workweek there is potential for two
winter weather systems to move through the forecast area allowing
for higher rain/snow amounts in comparison to that expected on
Thursday/Friday. These passing weather systems will have well
maintained moisture taps feeding into them as well as warm
trajectories of approach along the west edge of a ridge of high
pressure with axis placement to the east and a large area of low
pressure well off the coast. This warm trajectory of approach
supports a generally warming trend with rises in snow levels
allowing for intervals of rain as high as 4000-5000 feet MSL.
/Pelatti


&&

.AVIATION...
00Z TAFS: Late this afternoon, our air mass has become well mixed
for late January with temp/dewpoint spreads over 10 degrees across
much of central and eastern Washington. Clouds almost have a
spring-like convective look to them. Low stratus will probably be
slow to develop tonight with only the favored upslope TAFs of
KGEG, KSFF, and KCOE having low clouds included overnight. Rain
and snow is expected to develop along the Cascades in the morning
and spread across eastern WA through the day. /GKoch


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        29  36  35  39  29  35 /   0  80 100  90  80  20
Coeur d`Alene  29  36  35  38  29  35 /  10  70 100  90  80  30
Pullman        31  37  36  44  31  37 /  10  70 100  90  70  20
Lewiston       34  42  41  49  34  41 /  10  40  70  80  60  20
Colville       27  34  33  37  28  35 /   0 100  90  80  90  30
Sandpoint      28  35  34  36  28  34 /  40  90 100  90  80  50
Kellogg        28  36  35  37  28  34 /  60  50 100  90  80  50
Moses Lake     30  37  36  46  29  40 /   0 100  90  50  40  10
Wenatchee      29  34  33  38  26  35 /   0 100  90  50  40  20
Omak           27  34  33  36  26  33 /  10 100  90  90  80  30

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning from 1 PM Tuesday to 4 AM PST Thursday for
     Northern Panhandle.

     Winter Storm Warning from 4 PM Tuesday to 4 PM PST Wednesday
     above 3500 feet for Central Panhandle Mountains.

WA...Winter Storm Warning from 1 PM Tuesday to 4 AM PST Thursday for
     Northeast Mountains-Okanogan Highlands.

     Winter Storm Warning from 10 AM Tuesday to 4 AM PST Thursday for
     East Slopes Northern Cascades.

     Winter Weather Advisory from 10 AM Tuesday to 4 AM PST Wednesday
     for Okanogan Valley.


&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.