Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Boise Idaho
306 am MST Sat Dec 3 2016
Short term...today through Sunday night...a warm front will pass
over the region today, bringing clouds to most areas and a few
showers to the mountains. This is the forerunner to a strong
storm system that will bring heavy snow to the mountains Sunday
into Sunday night. The Winter Storm Watch has been changed to a
Winter Weather Advisory, indicating increased confidence in the
occurrence of a significant event. Ahead of the system, we will
see mostly cloudy skies today as temperatures reach near normal.
Snow showers will increase in the mountains, but snowfall totals
today will be an inch or less. Tonight, moisture will increase in
northwest flow aloft, and snow will increase further after
midnight. Amounts will initially be light, but by around 6 am MST,
snowfall will really start to pick up. Heavy snow will last
through the day and into the evening, with amounts averaging 5 to
9 inches between 5000 and 7000 feet, and 9 to 13 inches above 7000
feet. One area not in the advisory that will be closely monitored
is the upper Weiser river basin. The forecast is for the main
roadways to see mostly rain until late Sunday. Therefore that area
was not included in the advisory. However, it is a close call and
a change in the snow level of a few hundred feet could result in
snow-covered roadways and hazardous travel. Another area of
potential impact is Baker County. The mountains will see plenty of
snow, but at this time we are only forecasting about an inch in
Baker City and along the Interstate, so again no advisory has been
issued for that area.
The heaviest snow will fall Sunday afternoon into Sunday evening
as a strong cold front moves through. The timing of the front will
allow temperatures to reach near normal Sunday afternoon. Lift
from the front will enhance the ongoing snowfall. Snowfall rates
of an inch per hour will occur on northwest-facing slopes above
7000 feet. Wind gusts will briefly reach 20 mph in the lower
elevations, and up to 35 mph in the mountains as and shortly after
the front moves through. Snow will taper off after roughly
midnight, and the advisory is currently set to end at 11 PM MST.
Light snow will continue through the night, with additional
accumulations expected to be less than one inch. The cold front
will usher in the coldest air of the season to date. Lows Monday
morning will be 5 to 15 degrees colder than Sunday morning.
Long term...Monday through Friday...Monday will be partly cloudy
and cooler. An upper level trough originating over Alaska will
bring colder air and scattered snow showers Monday night and
Tuesday. Temperatures will be around 10 degrees below normal by
Wednesday. A warm front will spread snow showers across the area
Thursday and Thursday night, and scattered snow showers will
continue through Saturday, as temperatures moderate to near normal
under westerly flow aloft.
Aviation...north of a kbno-kono-Fairfield line, expect areas of MVFR
and local IFR ceilings through tonight, with scattered snow showers
and mountain obscuration. Elsewhere conditions will be mainly VFR.
Surface winds will be variable 10 kts or less. Winds aloft at 10k ft
msl will be northwest 25-35 kts.
Outlook for Sunday...widespread MVFR and areas of IFR conditions in
rain and snow. Mountains obscured. Snow levels 3000 ft in the
morning rising to 4500 feet in the afternoon.
Idaho...Winter Weather Advisory from 5 am to 11 PM MST Sunday idz011-013.
Short term...snow pellets