Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 171646
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
946 AM MST Fri Nov 17 2017

.DISCUSSION...An upper trough crossing the area today will keep
scattered showers across the mountains of e-central Oregon and
southwest Idaho through the day. Valleys will dry out with only
the Western Magic Valley keeping an isolated shower into the
afternoon. Northwest winds ramp up this afternoon across open
terrain. The strongest winds will focus over the central Snake
Plain which will see gusts to around 40 mph this afternoon. Made
minor update to the forecast for this morning to lower snow levels
and adjust precipitation chances across s-central Idaho zones.

&&

.AVIATION...Mountains obscured. Generally VFR except MVFR to IFR
south and east of KTWF in snow, tapering off after 20z. Isolated
MVFR-IFR snow showers developing from 18z-23z today over the higher
terrain. Surface winds: W-NW 10-20kt, strongest in the Magic Valley
with gusts up to 35kt possible, diminishing after sunset. Winds
aloft at 10kft MSL: NW 20-30kt becoming NW 10-20kt by 12z/Sat.

Weekend Outlook...VFR with mostly clear skies and light winds.
Patchy fog during the early morning hours Saturday and Sunday.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Saturday...
Cold front moving across the Idaho/Nevada border region early this
morning bringing showers across that region this morning.
Lingering light snow showers also expected across the west central
mountains of Idaho as the upper trough slides through the state.
Winds behind this front are the next big concern as the pressure
gradient increases. Model boundary level winds generally in the
15-25 mph range across southern Idaho and eastern Oregon. There is
sufficient instability where could see slightly stronger winds
aloft filter to the surface bring gusty winds to the region. The
strongest gusts (around 35 mph) are expected generally east of
Boise through the Twin Falls region.

Otherwise, an upper ridge builds into the region tonight through
Saturday bringing clear skies with near normal temperatures. So
have increased morning lows tonight as high clouds associated
with a weak system, remaining well north of the region, may help
keep tonight`s morning lows from getting too cold.


LONG TERM...Saturday night through Thursday...
An upper level ridge will stay in place over the region through
the end of the weekend. Clouds will begin to cover the skies late
Sunday ahead of the first of many disturbances in the extended
forecast. Accompanied by a deep moisture tap to the Pacific, this
disturbance will spread ample precipitation across the region late
Sunday through Tuesday. Snow levels will begin around 5000 ft
north and about 7000 ft along the Nevada border, creeping up
steadily through Tuesday. There will be a brief respite in
precipitation Tuesday before the next system works its way east
into our region. Precipitation will spread west to east once
again, tapering off by Friday morning. Snow levels will rise quite
a bit with this system as a southwesterly flow aloft anchors
itself over the region; the Idaho central mountains will see snow
levels up to about 9000 ft Wednesday, decreasing to about 8000 ft
Thursday. Precipitation will taper off Friday as the systems kicks
east. Temperatures will begin just a few degrees above normal
Sunday and increase to about 10 degrees above normal by the end of
the period.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.

&&

$$

www.weather.gov/Boise
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DISCUSSION...DG
AVIATION.....KA
PREV SHORT TERM...CR
PREV LONG TERM....AB


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