Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 072125

Area Forecast Discussion
National Weather Service Boise ID
225 PM MST Wed Dec 7 2016

.SHORT TERM...Tonight through Friday...Cool temperatures and
mostly clear skies today will produce one more chilly morning
tomorrow, before the next storm system begins to impact the area.
Snake River Valley locations are expected to experience lows
tomorrow morning in the teens and mountain locations will likely
see single digits. Thursday morning, a moist warm front will
begin to move into the area from southwest to northeast bringing
snow to the entire CWA. With the trapped colder air in the valley
locations, snow levels will be at valley floors through the day
Thursday. Snow amounts on Thursday are forecasted to be around
1-3 inches in the Treasure Valley and 2-4 in the Magic Valley,
with the bulk of the snowfall occurring between mid day and the
late evening. This timing will produce hazardous conditions for
the evening commute in the Treasure Valley, and thus a Winter
Weather Advisory is in effect for this time period. Precipitation
will taper off Friday morning in SE Oregon and the SE half of the
Idaho zones, but the warm front will have worked its way through
by then, bringing snow levels to 5000-6000 ft. However, snow is
expected to continue in the Idaho Central Mountains through
Thursday night and all day on Friday. This will bring snow totals
in those areas from Thursday morning through Friday to 5-10 in
most locations, and 15-20 above 7000 ft, and is the justification
for the advisory in those areas.

.LONG TERM...Friday night through Wednesday...A significant
Pacific weather system will continue moving through the region
Friday Night into Saturday. Forecast models are in good agreement
that this system will have a deep moisture tap throughout, leading
to nearly continuous precipitation chances as it passes. Snow levels
will be high enough initially for primarily rainfall in the lower
valleys, but by late Saturday levels will be low enough for snow to
at least mix with rain at nearly all valley locations. The westerly
flow associated with the system will focus upslope flow across both
the Blue Mountains and Steens of Oregon and the Central Mountains
of Idaho leading to significant snow accumulations.

There will be a brief respite for most areas, except the higher
peaks of both Oregon and Idaho, Saturday Night and early Sunday.
Thereafter another system is expected to pass through the area late
Sunday into early Monday, and another late Tuesday into Tuesday
Night. These later systems will support at least a mix of rain and
snow for valley locations, while mountain areas will see yet another
round of significant snowfall. Temperatures will run near to just
below average through this time frame.


.AVIATION...Generally VFR conditions have taken hold across the
area. The noted exception has been KJER which has been hanging on to
IFR ceilings much of the day. Conditions will slowly improve there
this afternoon, but as nightfall settles in the stratus may linger
into the overnight hours. Surface winds will pick up between 15 to
20 knots for both Treasure Valley and Magic Valley locations
overnight on into Thursday. These winds will be in response to the
approach of a significant weather system that will create widespread
IFR conditions mid day Thursday into Thursday Night. Accumulation of
snowfall is likely at all terminals. Mountains will be obscured
beginning early Thursday and will generally remain that way, with
short breaks, into early next week.


ID...Winter Weather Advisory from 11 AM Thursday to 5 AM MST Saturday
     Winter Weather Advisory from 11 AM Thursday to 5 AM MST Friday
     Winter Weather Advisory from 11 AM to 10 PM MST Thursday
OR...Winter Weather Advisory from 10 AM Thursday to 4 AM PST Saturday
     Winter Weather Advisory from 11 AM MST /10 AM PST/ to 10 PM MST
     /9 PM PST/ Thursday ORZ061-063-064.



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