439 
FXUS66 KOTX 101017
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
217 AM PST Tue Jan 10 2017

.SYNOPSIS...
The weather will turn more active on Tuesday and Wednesday as we 
see another round of brisk north winds developing which will 
likely produce areas of blowing snow in open areas as well as some
additional light snow accumulations. Expect significant impacts 
to travel and other outdoor activities. The winds will also create
some cold wind chills especially down the Okanogan Valley and 
across the western Columbia Basin. Look for mostly dry, chilly 
weather Thursday and Friday, before a chance of snowy weather 
returns this weekend.

&&

.DISCUSSION...
Today through Thursday morning...A warm front will nose into the
southwest zones this morning as the flow increases from the 
southwest with a weak low off shore. This will run head on into an
Arctic front dropping south out British Columbia later this 
morning. Pacific moisture will increase PWATs to around 100% of 
normal along with increasing lift through the dendritic layer as 
far north as about Highway 2 this morning. Then the warm front 
recedes south as the cold front drops into the region. As such we 
can expect 1 inch to possibly 2 inches of snow accumulation south 
of a line from Moses Lake east to about Lookout Pass. With little 
if any snow north of this line. As the cold front pushes south 
through the Inland northwest very dry air will follow and there 
will be rapid drying from north to south this afternoon and this 
evening. By tonight and into Wednesday only light snow 
accumulations will be possible for the extreme southeast zones, 
The Blue mountains and the Camas Prairie. 

Of bigger concern will be increasing northerly winds down the
Okanogan valley behind the cold front. These winds are expected 
to spill out onto the Waterville Plateau and the Columbia basin 
this morning. Sustained winds of 10 to 20 mph with gusts to around
30 mph will be possible. Through the afternoon and into this 
evening the winds will increase down northerly valleys across 
northeast Washington and finally the Purcell trench this evening. 
Neither the amount of snow or the strength of the winds would 
result in any kind of winter highlight. However the combination of
light powdery snow and breezy winds will likely result in blowing
and drifting snow today through this evening. A Winter weather 
advisory is in place for snow/blowing snow and that will be 
continued. 

Temperatures will begin a cooling trend today. This will effect
mainly the northern zones today where temperatures will cool 3-5
degrees from Monday and another 5-7 degrees on Wednesday. Across
the southern zones the cooling will take slightly longer with
temperatures only down 1-3 today, then really cool off on
Wednesday. Overnight lows will drop into single digits to lower
teens tonight with localized min temperatures below zero for the
northern mountain valleys. Clearing skies and light winds
Wednesday night will allow temperatures to cool to single digits
and localized areas below zero. Tobin 

Thursday through Friday night: Cold and dry. A dry northerly flow 
will be over the Inland NW for the end of the week as surface 
high pressure sets up over northeast Washington. Winds will taper 
off and skies clear. Radiational cooling and snow cover will send 
temperatures to bitter cold values in the single digits, possibly 
below zero. Daytime highs will be the teens to lower 20s. Low 
level inversions will strengthen Thursday night into Friday and 
could see some patchy freezing fog in the northern valleys. By 
Friday night, a weak upper level impulse will push through the 
region with plenty of high clouds and possible light snow near the
Cascade crest. The clouds will help moderate temperatures 
slightly. 

Saturday through Monday: Wetter and milder. The storm track will
take aim on the Pacific northwest for the weekend and early next
week as a series of Pacific systems head toward the region.
Confidence on the timing of these systems is poor with the GFS
being more aggressive and wetter than the ECMWF that has a
stronger ridge to break down. The next weather system looks fairly
weak and should arrive in the Saturday night into Sunday time
period. Snow levels will remain low while temperatures gradually
rebound. By Sunday night into Monday, another weather system will
pass through the region with a better chance of precipitation. As
temperatures continue to warm slightly, there is a threat of mixed
precipitation in the LC valley, Palouse and Columbia Basin by
Sunday afternoon. The mild and wet trend persists into early next
week with rising snow levels, temperatures climbing above seasonal
normals and more rain than snow across the region. Could even see
more of a wintry mix developing into the Cascade valleys and
Okanogan valley. This scenario will need to be monitored
especially with the current snow pack and the issues that arise
with a rain on snow pattern. /rfox. 

&&

.AVIATION...
06Z TAFS: A moist boundary layer will result in low stratus and 
fog tonight into Tuesday. Best potential for fog will be over the 
basin and into the Lewiston-Clarkston Valley with low stratus more
likely everywhere else. The fog is expected to break up as a band
of snow arrives Tuesday morning. Best chances for snow will be at
KPUW and KLWS into at least early Tuesday afternoon. MVFR/IFR 
cigs are expected for these TAF sites with the snow. It is 
possible that the snow will remain south of the Spokane/Coeur 
d'Alene corridor. Drier air will begin to push into the region 
along an Arctic front during the day on Tuesday. Cigs/vis will 
improve from north to south along this front with VFR conditions 
possible at KEAT, KMWH, KGEG, KSFF and KCOE by mid afternoon. 
Northerly winds will increase as well with breezy conditions and 
gusts to around 20 kts possible for KWMH and KCOE late in the 
afternoon Tuesday or by the evening. /SVH

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        26   6  17   0  12   2 /  40  10  10  10   0   0 
Coeur d'Alene  28   7  19   1  14   4 /  40  10  10  10   0   0 
Pullman        31  12  21   6  17   7 /  80  30  40  10  10   0 
Lewiston       34  19  26  14  22  10 /  80  40  60  20  10   0 
Colville       23   1  17  -2  15   1 /  10   0   0   0   0   0 
Sandpoint      27   7  20   2  14   3 /  30  10  10   0   0   0 
Kellogg        28   9  19   4  16   4 /  80  20  30  10  10   0 
Moses Lake     27   6  19  -4  10  -1 /  60  10  10   0   0   0 
Wenatchee      24   9  19   4  16   3 /  50  20  10  10   0   0 
Omak           22   6  17   3  14   2 /  10   0   0   0   0   0 

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory from 1 PM this afternoon to 10 AM PST 
     Wednesday for Coeur d'Alene Area. 

WA...Winter Weather Advisory from 1 PM this afternoon to 10 AM PST 
     Wednesday for Spokane Area-Washington Palouse. 

     Winter Weather Advisory from 7 AM this morning to 10 AM PST 
     Wednesday for Moses Lake Area-Upper Columbia Basin-
     Waterville Plateau. 

&&

$$