Heavy Snow in Idaho, January 8 to 9, 2017

Area Forecast Discussion
National Weather Service Boise ID
229 PM MST Sun Jan 8 2017

.SHORT TERM...Tonight through Tuesday...Well-defined warm front
moving north through our CWA this afternoon and evening. The front
passed through Boise around 1230 PM MST with gusty southeast wind,
a sharp rise in temperature, and a changeover from snow to rain.
Lower wind-sheltered areas have stayed cold and will experience a
freezing rain event through this evening with an accumulation of
ice, especially in the Lower Treasure Valley west of Caldwell,
ID, the Upper Weiser River area, most of Baker County and the
northern parts of Malheur and Harney Counties. Farther south
precipitation will be rain. By late evening the snow level will
be at maximum height: 4500 feet MSL north to 6000 feet MSL south.
North of the warm front, and at higher elevations in central
Idaho, precipitation will continue as snow. Next will come the
cold front from the west overnight. The cold front will lower the
snow level back to near 4000 feet MSL Monday morning. Precipitation
along the front will add another couple inches new snow above the
snow level with rain below, except local freezing rain continuing
in the lowest wind-sheltered valleys. Showers, generally in the
form of snow, will continue in the cooler air Monday night and
Tuesday as the main Pacific upper trough comes fully inland.

.LONG TERM...Tuesday night through Sunday...An active weather
pattern still on track through the extended period. Several weather
systems will track over the Pacific Northwest. Each weather system
will push a warm front north over the forecast area followed by a
cold front, then the scenario repeats when the next weather system
moves through. Mountains will remain all snow with lower valleys
switching between rain and snow. Models hinting at a possible
break in the weather for the weekend, but models have not been
doing well that far out so will keep at least some low pops in the
forecast. Temperatures will remain at or below normal.

&&

.AVIATION...Generally VFR/MVFR with mountain obscuration.
Precipitation type remains tricky but lower valleys are slowly
mixing out the cold air. KBOI has changed over to rain and expect
KTWF/KJER and KBNO to change to rain around 00Z. Looks like KEUL may
stay all snow as the cold air remain in the Lower Treasure Valley.
KMYL will remain all snow and think KBKE will remain all snow, but
may have a brief period of rain/snow mix. Surface winds east to
south 5-15 knots with gusts around 25 knots. Winds aloft
southwesterly 30-40 knots up through 10K feet MSL.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Winter Storm Warning until 11 PM MST this evening IDZ013-028.
     Winter Weather Advisory until 5 PM MST this afternoon IDZ014-016.
     Areal Flood Advisory until 6 PM MST Monday IDZ012.
     Ice Storm Warning until 11 PM MST this evening IDZ011-012-033.
OR...Ice Storm Warning until 11 PM MST /10 PM PST/ this evening
     ORZ061>064.

&&

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SHORT TERM...LC
LONG TERM....JA/JC
AVIATION.....JA