Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 251057

Area Forecast Discussion
National Weather Service Boise ID
357 AM MST Sun Feb 25 2018

.SHORT TERM...Today through Monday...A vigorous upper level trough
is moving south along the British Columbia coast this morning with
moisture streaming into the Pacific Northwest. Temperatures this
morning are colder than anticipated, thus have lowered high
temperatures for today slightly. Snow will develop across the
west central Idaho mountains and Baker County OR this morning and
become widespread across much of the region by this evening, with
the exception of precipitation shadowing directly east of the
Owyhee Mountains of SW Idaho and Steens Mountain in SE Oregon.
Westerly flow aloft will favor heavy snow across the West Central
Mountains and Boise Mountains ahead of the cold front. The cold
front will move through the region late Sunday night and into
Monday morning. Snow will taper off quickly behind the cold front
from NW to SE on Monday, with isolated snow showers continuing
across the central ID mountains and south along the NV ID/OR
border through Monday evening. Breezy northwest winds are expected
on Monday afternoon behind the cold front.

.LONG TERM...Monday night through Saturday...Snow showers end Monday
night as the trough axis swings through and the main upper low moves
far to the southwest. Northwest flow Tuesday will back to westerly
on Wed in advance of another system, and mountain snow showers are
possible through this time. This large strong system will spread
snow to all areas Wed night through Friday, with several periods of
snowfall for lower elevations and nearly continuous snow for the
mountains. Mountains could easily end up with over a foot of new
snow with this storm. A cold front will move through Friday,
continuing the chance for precipitation. Snow showers remain
possible through next weekend as we reside under a broad upper level
trough. Temperatures will remain well below normal through the
extended period.


.AVIATION...VFR initially. Mountains deteriorating into IFR with
snow after 12Z. Lower elevations VFR/MVFR after 15Z in snow showers.
A cold front will move through tonight, bringing additional snow.
Surface winds: southeast to southwest 10-20 kts except 15-25 kts
over the higher terrain, transitioning to northwest after 26/00Z.
Winds aloft at 10k ft MSL: northwest 25-35 kts becoming west 30-40
kts after 21z.


ID...Winter Storm Warning until 5 AM MST Monday IDZ011-013-033.
     Winter Weather Advisory from 2 PM this afternoon to 5 AM MST
     Monday IDZ014>016-028>030.
OR...Winter Weather Advisory from 2 PM MST /1 PM PST/ this afternoon
     to 5 AM MST /4 AM PST/ Monday ORZ061-063.
     Winter Weather Advisory until 10 PM PST this evening ORZ062.



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