Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 171057

Area Forecast Discussion
National Weather Service Boise ID
356 AM MST Wed Jan 17 2018

.SHORT TERM...Areas of valley fog this morning, locally dense in
the Treasure Valley, otherwise mild and generally dry today as a
weak warm front passes through.  However, the front will produce
a slight chance of light rain/snow over higher terrain in Baker
County.  Deep low in the Gulf of Alaska will circulate warm southwest
winds aloft into our CWA late tonight and especially Thursday.  Full
mixing will occur in the southern valleys, and temps will rise to
near record highs Wednesday.  East or southwest winds will blow
20 to 30 MPH in most of the Snake Basin.  Later Thursday the
storm`s cold front will move inland with widespread rain and
high-mountain snow in eastern Oregon and the west central Idaho
Mountains.  Rain will begin in the southwest Idaho valleys Thursday
afternoon and reach the western Magic Valley early Thursday evening.
The cold front will bring an end to the warm weather.

.LONG TERM...Thursday night through Tuesday...Active weather
expected through the extended period with seasonable temperatures. A
cold front will move across the region on Friday morning. Snow
levels will be quite high (around 6500-8000ft MSL) with the onset of
precipitation, then slowly lower as the cold front moves through the
region. Snow amounts across much of the mountains will be limited to
the second half of the storm, as temperatures aloft remain warm
through Friday morning. The West Central Mountains look to have the
highest accumulations with this storm. Snow levels will fall to
around 3500-4500ft MSL for the second half of the storm, as
precipitation begins to taper off on Friday afternoon in the
valleys. Little or no snow accumulations expected in the valleys
below 3500ft. Snow showers across the mountains will continue
through Friday night and taper off after sunset. Expect mountain
snow showers during the day on Saturday afternoon, with the cool air
aloft helping to create instability showers over the terrain. The
next system moves into the region late Sunday, bringing a warm front
and subsequent cold front. Snow is expected across much of the area
before snow levels begin rise above the lowest valley floors (3000-
3500ft) with the warm front. The cold front with this system moves
through the area on Monday morning, lowering snow levels back to the
valley floors as snow showers taper off in the valleys and continue
in the mountains. Another system follows on Wednesday bringing
another warm front which should start pcpn out as snow before snow
levels rise above the lowest valley floors (3000-4000ft).


.AVIATION...Fog and stratus through 18z/Wed across much of the
area. Decreasing clouds and VFR during the afternoon. Light surface
winds becoming southeasterly 10-20kt after 18z/Wed. Winds aloft to
10k feet MSL: SW 20-30kt becoming SW 40-55kt by 06z/Thu.





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