Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 200245

Area Forecast Discussion
National Weather Service Boise ID
845 PM MDT Thu Oct 19 2017

.DISCUSSION...No updates. The cold front, which is currently
located in central Oregon, is still on track to move across SE
Oregon late tonight and SW Idaho Friday morning. Gusty winds to 40
mph will accompany the front. Rain will also accompany the front,
followed by showers associated with an upper trough on Friday.
Snow levels will lower to around 5000 feet on Friday with light snow
accumulations expected mainly in the West Central/Boise Mountains
above 5500 feet. Temperatures will be 15-30 degrees cooler on
Friday with highs only in the 40s and 50s. Breezy to locally windy
conditions (15-25 mph with higher gusts) are also expected through
the day.


.AVIATION...VFR with increasing and lowering clouds tonight ahead
of a Pacific cold front, currently timed to arrive in KBKE and
KBNO about 06Z, KMYL and KBOI about 09Z, and KTWF and KJER about
12Z. Expect deteriorating conditions, with showers spreading
across the area, with areas of mountain obscuration and MVFR
ceilings. Snow levels lowering to 5-6kft MSL Friday morning and
around 5kft MSL by Friday afternoon. Surface winds: generally SE
to SW 10-20 kts, shifting to the W in the front`s wake. Winds
aloft near 10kft MSL: SW 30-40 kts, turning W behind the front.


SHORT TERM...Tonight through Saturday...Satellite data continues
to show increasing cloud cover across the Pacific Northwest this
afternoon, with observations noting hints of the cold front moving
off the Pacific coastline. Gusty winds noted across Oregon and
portions of central Idaho this afternoon ahead of this anticipated
front. Models continue to indicate this front arriving into
eastern Oregon late tonight and moving into southwest Idaho early
Friday morning. As the front progresses, expect the threat for
gusty wind to continue, with precipitation expected to accompany
the front. Snow levels will decrease to around 6k ft tonight,
leaving mountain snowfall possible. Temperatures on Friday are
expected to be between 10 and 20 degrees cooler than today. Shower
activity will weaken through the evening hours as the front moves
east of the area. However, another push of moisture will move
into eastern Oregon late Friday night, spreading across Idaho on
Saturday afternoon and evening. This will continue to wet and cool
pattern, with temperatures remaining generally 5 to 10 degrees
below normal.

LONG TERM...Saturday night through Thursday...Moist westerly flow
aloft will continue to support showers, mainly over the mountains
of Baker County Oregon and west central Idaho, through Sunday
night. An upper level ridge building over the west coast will cut
off the moisture supply on Monday. Tuesday night an upper level
trough from the Gulf of Alaska will weaken as it moves into
British Columbia and encounters the ridge. The trough will slide
southeast across northern Idaho and western Montana Wednesday
afternoon and evening as the ridge rebuilds offshore.
Precipitation with this system is expected to stay north and east
of our area, and there will be little effect on temperatures,
which will continue near or slightly above normal.





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