Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 032201

Area Forecast Discussion
National Weather Service Boise ID
301 PM MST Sat Dec 3 2016

.SHORT TERM...Tonight through Monday...Mid to upper level cloud
coverage will increase tonight from the northwest as a strong
upper level system approaches the region. Ahead of this system,
a northwest flow aloft will allow for a continuation of light
snow accumulations this evening over the mountains. Upper level
flow will combine with a deep moisture plume overnight, bringing
more significant snow accumulations to the mountains in the early
morning hours through the day Sunday. Light precipitation expected
elsewhere with snow levels around 3500-4500 FT MSL. A Winter
Weather Advisory is now in affect for the Weiser River Valley from
5 AM MST and 5 PM MST and the West Central and Boise Mountain from
5 AM MST and 11 PM MST Sunday. Light snow showers will continue
for a few hours after the advisory ends. The Boise metro may see a
brief period of light snow Sunday morning as precipitation first
begins and again Monday morning as the cold front transitions
through the area, just in time for the morning commute. As the
cold front exits the region Monday morning, a dry and cold air
mass will move into the region. Monday`s high temperatures will
be about 8-12 degrees lower than Sunday`s for temps in the lower
30s in the lowest valleys. The next system will approach the
region Monday and begin to enter the region from the northwest
late Monday evening. All precipitation is expected to fall as
snow, though snowfall will be light.

.LONG TERM...Monday night through Saturday...The cold air mass is
reinforced as an upper low tracks south out of British Columbia on
Tuesday. This will bring a chance of light snow to the region as
snow levels are down to valley floors. The low center tracks through
southwest Oregon to the ID/NV border, which will be the focus of
higher snow amounts. Wednesday is dry and cold under northwest flow
aloft. Though slight timing differences remain between the GFS and
ECMWF, there is good agreement that by late Thursday moist westerly
flow will bring another round of precipitation to the interior
northwest. With cold air trapped at the lowest levels precipitation
could start as snow at all elevations before changing to rain late
Thursday or possibly Friday. The pattern remains cold and unsettled
into the weekend. Temperatures will be 5 to 10 degrees below normal
through Thursday, warming back towards normal for the weekend.


.AVIATION...Local MVFR in the southwest Idaho mountains this
afternoon obscuring mountain tops. VFR conditions elsewhere across
southeast Oregon and southwest Idaho. Light surface winds of 10 kts
or less and northwest winds aloft of 20 to 30 kts through 10k feet

Tonight and Sunday: IFR conditions and snow develop after 06Z in
east-central Oregon and west-central Idaho mountains, and after 18Z
in southeast Oregon and the Snake Plain of southwest Idaho to the
ID/NV border. Sites above 4500 feet will see IFR in snow through the
day with widespread mountain obscuration. Lower sites could start as
rain/snow mix Sunday morning, but no accumulation is expected and it
will quickly change to rain. Surface winds are 10-20 kts across open
terrain with the strongest winds across southeast Oregon on Sunday.
Will see west winds aloft of 40-50 kts up through 10k feet MSL.


ID...Winter Weather Advisory from 5 AM to 11 PM MST Sunday IDZ011-013.



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