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Area forecast discussion
National Weather Service Boise Idaho
310 am MST Fri Dec 6 2019

Short through Monday...low clouds continue in the
valleys this morning, although the fog has not been as extensive
due to the clouds and more wind compared to last night. Southwest
flow aloft will increase and become moist tonight through Saturday
as a low pressure system off the coast moves inland. Precipitation
will spread from southeast Oregon tonight into southwest Idaho on
Saturday. Snow levels will generally range from 4000 to 5000 feet.
The system will gradually move across the area through Sunday.
Valley rain and mountain snow will transition to showers on
Sunday, then taper off Sunday night with the arrival of dry
northerly flow aloft that will continue through Monday. Total snow
accumulations of 5-10 inches are expected over the weekend in the
northern mountains above 5000 feet. Temperatures will be above

Long term...Monday night through Friday...a brief ridge will
build over the Pacific northwest coast on Tuesday, maintaining dry
conditions as temperatures stay a couple degrees above normal. A
disturbance approaches the region Wednesday night, spreading an
initial wave of snow showers across the region. Model solutions
differ on the timing of another system entering the intermountain
west beyond Thursday, so a chance of precipitation was maintained
across the area. Snow levels are expected to rise above 4500 ft
mean sea level by Friday, resulting in rain at lower elevations. Conditions
will remain unsettled into next weekend as models continue to show
moist flow pushing into the northwest.


Aviation...widespread MVFR with pockets of IFR/LIFR conditions
due to fog and stratus through the morning, then conditions
gradually improving after 06/16z. Mountains obscured. Surface
winds: east to southeast 5-15 kts. Winds aloft at 10kft msl: SW 15-30 kts.

Weekend outlook...valley rain and mountain snow (around 4k-5k
feet mean sea level and above) will increase Saturday from west to east, and
then taper off on Sunday. Rain and snow will create MVFR/IFR
conditions and mountain obscurations. Winds aloft at 10kft mean sea level
will increase to SW 40-50 kts Saturday, then become northwest 15-30 kts


Air stagnation...inversion and light winds will continue through
early this afternoon. The inversion will weaken later this
afternoon through Saturday as an approaching system increases
winds which will improve mixing.


Boi watches/warnings/advisories...
Idaho...air stagnation advisory until 2 PM MST this afternoon
Or...air stagnation advisory until 2 PM MST /1 PM PST/ this afternoon




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