Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 151942

Area Forecast Discussion
National Weather Service Pocatello ID
142 PM MDT Fri Sep 15 2017

.DISCUSSION...A low pressure system will move out of the central
Idaho mountains and through the upper snake highlands near Island
Park tonight. Precipitation will wrap around the backside of the
low and slide through the northern much but not all of eastern
Idaho tonight. Expect snow levels to fall to 6000-6500 feet
tonight. Am expecting a couple inches near some of our higher
passes from Willow Creek Summit to Monida Pass, Raynolds Pass and
Targee Pass. Will hold off on an advisory since it appears the
better accumulations will be mainly at pass level and much of the
snow will be melting on the road surface. Still, some slushy or
icy conditions are likely in these locations by morning.
Elsewhere, looking at breezy conditions across the Magic Valley
for a couple hours this evening before the winds diminish. Expect
clearing conditions across the region on Saturday with the Island
Park area likely the last to see clearing, probably not afternoon
there. Cold conditions settle across the region Saturday night
into Sunday morning with patchy frost possible in some areas
across the Snake Plain depending upon cloud cover.

The next system arrives late Monday and Monday night in the form of
another cold front. Looks like we could see some impressive rainfall
amounts once again with this system, potentially up to half an inch
possible. Snow levels will start off around 8000 or 9000 feet but
then fall to around 6500 feet behind the front. Models showing some
lingering precipitation on Tuesday so high elevation snow is
certainly possible once again, possibly affecting the higher passes.
A stronger push of moisture arrives for Wednesday and persists into
late week which will produce another good shot of precipitation
areawide. Snow levels look like they may hold around 6000-6500 feet.



.AVIATION...Deep upper trough continues to linger over Idaho this
afternoon with widespread multi-layer cloud cover. Some clearing is
noted associated with a dry slot over the Snake Plain, and this is
resulting in gusty surface winds. Rain associated with a short wave
is lifting through KIDA, though models are suggesting the
development of another wave which will impact KPIH and KIDA tonight.
Expect gradual improvement from west to east tomorrow morning as the
upper trough moves to the east. Hinsberger


.FIRE WEATHER...Gradual west to east drying for most of southeast
Idaho starting tomorrow morning as a deep upper trough slowly moves
out of the area. We will be left with fair weather through the
weekend with cool overnight lows. Breezy conditions are expected
across the Snake Plain today, but winds will taper off this evening.
Light snowshowers in the overnight hours, mainly over Lemhi and
Custer counties. Showers will be over Zones 410 and 411 tomorrow
morning, and those should diminish by tomorrow afternoon. Our next
storm of concern will be Monday as an upper low approaches the PAC
NW. Winds will increase Monday afternoon to around 25 to 30 mph
sustained with highest gusts in the Central Mountains to near 40
mph. Humidity during this time will be 25 to 35 percent, curtailing
any Red Flag concerns. Hinsberger



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