Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 091716
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
1016 AM MST Fri Dec 9 2016

.DISCUSSION...A wintry mix continues to fall across much of the
area this morning with precipitation expected through the rest of
the day. A warm front is continuing is slow movement across the
area. The cold air trapped in the valleys is making the front hard
to find with temperature fields, but the Southwest portion of the
CWA is showing some 40s around 4000 ft or so, with upper 20s in
the neighboring valleys. Current forecast has this warmer air
beginning to mix down mid day today and through the afternoon
hours. Valley locations, including the Snake River Plain should be
changing to all rain this afternoon, and mountain locations,
especially the Idaho Central Mountains, will continue to
experience steady snowfall. The advisory in the Magic Valley and
Southern Twin Falls County will be allowed to expire at 11 am MST
as forecasted, as the threat of winter weather impacts diminishes.
Otherwise, no updates to the forecast are needed at this time.

&&

.AVIATION...A mixture of rain, freezing rain, ice pellets and
snow can be expected over much of southeastern Oregon and
southwestern Idaho today. Expect MVFR ceilings and visibilities in
most valley locations. Expect snow in the mountains above 5000
feet to be associated with IFR ceilings and visibilities.
Mountains are obscured. SFC winds will be light and variable at
most locations. Winds aloft around 10 KFT will be westerly 25 to
30 kts.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Saturday...Cold air remains locked in
place over much of southeast Oregon and southwest Idaho. Only
sites above freezing this morning are those above 4k feet across
southern Harney/Malheur counties and areas south of the Snake
River in southwest Idaho. This is resulting in some light freezing
rain in the western Magic valley and light snow across the lower
Treasure valley and west-central and Boise mountains. Cold air
will be slow to erode, with temperatures likely not getting above
freezing until late morning for valley sites above 2500 feet.
Result will be a chance of light snow or freezing rain through about
noon. At lower elevations the best chance for additional snow
accumulation will be from Baker City to west of Caldwell which keep
subfreezing temperatures through the day. Thus have continued snow
advisory for the lower Treasure Valley though this afternoon.
Mountains of east-central Oregon and west-central Idaho will see
snow intensity pick up this afternoon as the warm front moves
northeast. Snow tapers off over east-central Oregon this evening,
but will continue across the southwest Idaho mountains and far
southeast Oregon Friday night and Saturday as moist westerly flow
follows the warm front. Snow levels will range from 4k feet over the
west-central Idaho mountains to around 6k feet along the ID/NV
border. After this evening little additional accumulation is
expected in lower valleys, even those that remain cold enough for
snow.

LONG TERM...Saturday night through Thursday...Active weather
pattern still on track through the extended period. Upper level
flow will remain zonal Saturday night through Tuesday, then shift
to a northwesterly flow Tuesday night through at least Thursday as
an upper level trough digs south through Canada. With this weather
pattern models indicating precipitation through the extended
period, but with the shift in the flow aloft Tuesday into Tuesday
night could see a brief dry period before the next round of
precipitation spread over the region. Snow level generally down to
valley floors, but the lowest elevations below 2500 feet could see
a mix of rain and snow. Temperatures through the extended will be
near normal.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Weather Advisory until 11 AM MST Saturday
 IDZ016-013-028-033. Winter Weather Advisory until 11 AM MST this
morning IDZ016-030. Winter Weather Advisory until 5 PM MST this
afternoon IDZ012. OR...Winter Weather Advisory until 5 PM MST /4
PM PST/ this afternoon ORZ062-064.

&&

$$

www.weather.gov/Boise
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www.twitter.com/NWSBoise

DISCUSSION...EP
AVIATION.....JB
PREV SHORT TERM...DG
PREV LONG TERM....JA



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