Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 111110

Area Forecast Discussion
National Weather Service Boise ID
334 AM MST Sun Dec 11 2016

.SHORT TERM...Today through Monday...Strengthening westerly flow
aloft and afternoon instability will support light snow showers
across the east-central Oregon and west-central Idaho and Boise
mountains today. Lower valleys will battle the inversion and
accompanying fog. Expect the dry air and wind aloft to erode much
of the fog from the Snake Plain by late morning with just the
lowest elevations along the OR/ID border keeping patchy fog into
the afternoon. Fog reforms in these areas again tonight. Gusty
winds will develop across the higher terrain of southeast Oregon
and southwest Idaho this afternoon as the increasing winds aloft
mix to the surface. Light snow continues in the mountains
overnight, but will increase in coverage and intensity on Monday
as an upper wave tracks across the region. This feature could
also bring a period of light snow to the Snake Plain Monday
morning for areas near the foothills. Snow totals in the mountains
through Monday will be 3-6 inches with up to 8 inches across
higher peaks.

.LONG TERM...Monday night through Saturday...Even though latest model
runs seem to be similar in solution, there is a big difference on
timing and placement of precipitation. With these big differences in
the latest model runs decided not to make many changes to the
extended forecast. Model trend still shows an arctic low dropping
south out of Canada east of the continental divide, with a weaker
low off the Pacific Northwest coast. As the weaker low sinks slowly
south Monday night through Wednesday night models showing a weak
ridge of high pressure building over the forecast area. Where the
models differ is in how far north precipitation will be. Previous
model runs had the warm front stalling roughly over the Snake River
Valley, with current runs keeping the warm front south of Idaho
along with the majority of the precipitation. As the weaker low
shifts inland Thursday through Friday will see increasing pops over
the forecast area, but again some uncertainty as to how much. As
this weaker low shifts east of the forecast area Friday night into
Saturday will see decreasing pops over the region, but will also see
arctic air move into the area. If current model trends are right
high temperatures by next Saturday will be in the teens.


.AVIATION...Widespread LIFR/IFR conditions in fog in the Snake River
Valley, Weiser River Valley and Baker Valley through 18Z, but it is
possible that these conditions will remain through the day from KEUL
west to KONO. Rest of the forecast area will have local low VFR/MVFR
conditions this morning, with partly cloudy skies this afternoon.
Surface winds light and variable this morning, becoming southeast to
southwest 5-15 knots this afternoon. Winds aloft westerly 20-30
knots up through 10K feet MSL.


ID...Dense Fog Advisory until 10 AM MST this morning IDZ012-014-033.
OR...Dense Fog Advisory until 10 AM MST /9 AM PST/ Sunday ORZ062-064.



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