Area Forecast Discussion
Issued by NWS Pocatello, ID

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078
FXUS65 KPIH 110926
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
226 AM MST Thu Jan 11 2018

.SHORT TERM...Today and Friday...All is calm this morning under a
weak weather pattern and ahead of a series of short wave troughs
later today through Friday morning. The most impactful trough is
expected during the overnight hours, from about midnight to 6 am,
affecting all of SE Idaho in slightly different ways. First
though, as the first trough passes through this afternoon and low
snow levels are already in place; expect a period of snow showers
before snow levels rise during the late afternoon/evening and
precip transitions over to rain across the southern Snake River
Plain. Snow showers will persist in the northern Snake Plain and in
the mountainous terrain as the next, stronger shortwave passes
the region overnight. This will bring periods of heavy snow and
blowing snow at times. Accumulations of a foot or more are
possible on the western facing slopes of the Sawtooth Mountains
and in portions of the Salmon-Challis and Caribou-Targhee NF`s.
Meanwhile, winds will be of concern across the Snake River Plain
during the overnight hours as wind speeds of 30 mph and gusts to
50 mph are expected to develop after 10 pm MST and persist for
several hours; weakening before sunrise. Person should secure any
loose items outdoors or bring them indoors.

Conditions begin to improve during the day Friday as upper level
flow shifts more from the northwest once more, though lingering
snow showers are expected in the east for those near the Wyoming
border. Expect winds to dramatically improve Friday night as well
to less than 10 mph.
NP/Valle

&&

.LONG TERM...Saturday through Thursday.

A weak system will try to move overtop the ridge on Saturday. This
could produce some very light snow for the upper Snake highlands. Am
not really expecting it, the models are probably keying more on low
stratus and fog in the area, but with some low to mid cloud forecast
to move overtop the area, could see some light snow or flurries
around Ashton to Island Park. Otherwise dry weather should continue
into Tuesday. We expect a big shift in the overall pattern to much
wetter. Most of Tuesday should be dry but we expect a system to
arrive Tuesday night which will bring precipitation to the
region. This could be another problematic warm system with snow
levels sitting just off the valley floors. If enough cold air gets
trapped in the valleys, could see some freezing rain in those
valleys once again. Models diverge for Wednesday and Thursday with
the GFS mainly dry Wednesday but bringing wet weather into the
area Wednesday night and Thursday. The European keeps us dry
during this time, but eventually brings a wet onslaught into the
area, just a difference in timing really.

Valle

&&

.AVIATION...Another storm system will arrive today. Expect worsening
conditions through the day with gusty winds developing by afternoon.

Valle

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 PM this evening to 6 AM MST Friday for
IDZ020-021.

Winter Weather Advisory from noon today to 3 PM MST Friday for
IDZ019-023-025.

Winter Weather Advisory from 9 AM this morning to 9 AM MST
Friday for IDZ018-031.

&&

$$



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