Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 191537
AFDBOI

Area Forecast Discussion
National Weather Service Boise ID
937 AM MDT Thu Oct 19 2017

.DISCUSSION...Dry and mild today ahead of tomorrow`s trough and
associated cold front. Expect gusty wind to develop across the
area today, especially SE Oregon where winds around 20 mph will be
possible this afternoon. Front still anticipated to move through
the area tonight and into Friday morning, with cold and wet
conditions through the day. Secondary moisture push remains on tap
for Saturday, keeping the cold and wet conditions going into the
weekend. No changes needed to current forecast.

&&

.AVIATION...VFR today with mostly clear skies. Clouds increasing and
lowering this evening ahead of a Pacific cold front. Front moving
through late tonight and early Friday with widespread showers,
mountain obscuration, areas of MVFR ceilings. Southeast to southwest
surface winds increasing to 10-20 kts this afternoon, shifting to
west 10-20 kts following front. Winds aloft at 10kft MSL southwest
30-40 kts.

&&

.PREV DISCUSSION...
SHORT TERM...Today through Friday night...One more mild and dry
day ahead of an approaching upper trough and cold front.
Southwest flow aloft will bring 20-30 mph winds to southeast
Oregon and higher terrain of southwest Idaho by this afternoon.
Easterly winds will funnel through the Snake Plain, the downslope
winds aiding in warming temperatures. Clouds increase through the
day with precipitation developing Thursday night across southeast
Oregon, spreading into southwest Idaho Friday morning. Strong
pre-frontal southwest flow will initially focus precipitation in
the mountains with rain filling in across lower elevations Friday
morning as the cold front passes. The heavier precipitation will
fall as snow levels drop from around 8k feet to around 6k feet
Friday morning, thus limiting snow accumulations to sites above
6k feet. By Friday afternoon snow levels are down to around 5k
feet, but additional accumulation will be localized as
precipitation scatters out. Westerly winds ramp up Friday with
speeds of 20-35 mph developing across open terrain during the
afternoon. Lower elevations dry out Friday night, with shower
coverage decreasing across the mountains as the upper trough exits
eastward. Will see a 15-20 degree drop in high temperatures from
today to Friday.


LONG TERM...Saturday through Wednesday...With a large push of
moisture into the coast, combined with a surface warm front moving
south to north across the area, widespread precipitation is
expected on Saturday. Snow levels will rapidly rise to 8000 ft or
more. Model agreement is quite high, with the NAM being slightly
slower with the onset of precip. Nonetheless, the impacts are in
agreement. Lingering showers on Sunday in northern portions of the
CWA will give way to a ridge building in on Monday. Conditions
are expected to be dry Monday and beyond with temperatures near
normal.

&&

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

&&

$$

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DISCUSSION...KB
AVIATION.....JT
PREV SHORT TERM...DG
PREV LONG TERM....EP



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