Winter Storm and Winter Weather in Idaho, February 15 to 17, 2020

Area Forecast Discussion
National Weather Service Pocatello ID
220 AM MST Sat Feb 15 2020

.SHORT TERM...Today through Sunday night. We are seeing a little
bit of morning fog or stratus across the Upper Snake Plain into
the Island Park area. There also appears to be some as well around
Palisades, and eventually we think the Bear Lake area. Otherwise,
clouds and precipitation will be increasing through out the day.
Anything that falls will be on the light side even up in the
mountains. What falls in the Snake Plain will be very limited,
across the far Upper Plain. Winds will ramp up again, but not as
strong as yesterday...yet.

Saturday Night and most of Sunday looks wet and windy. With west
to northwest flow, favored areas will be the Sawtooths and Wood
River area...as well as most of the eastern and southeast
highlands. Snow levels rise to between 5000-5500ft, potentially
maybe even 6000ft across the southeast corner. Winds really pick
up Sunday across the area as well. In terms of snow related
headlines...we continue with a WINTER WEATHER ADVISORY for the
Sawtooths and Wood River area, as well as the Bear Lake and Teton
Valley areas. A WINTER STORM WARNING is also in effect for Island
Park, the Big Holes and the rest of the southeast highlands.
Strong winds will mean some blowing and drifting especially at
higher elevations. Warmer temperatures at lower elevations will
lead to a mix or wet accumulating snow. This will also mitigate
blowing/drifting issues most likely at lower elevations. We will
likely need a WIND ADVISORY for portions of the Snake Plain and
Magic Valley Sunday afternoon and evening. Snow quickly winds down
Sunday night. The focus shifts to the southern and
eastern/southeast highlands after sunset...with winds gradually on
the decrease. We will be watching for a possible convergence band
developing north of Idaho Falls and Rexburg. Confidence is low but
the signal is there in the models.  Keyes

.LONG TERM...Mon through Fri night. Residual light snow continues
Mon and Mon night, mainly in the eastern highlands and in the
central Idaho mountains in the areas north and west of Galena
Summit. The moisture combining with the upslope flow finally wraps
up late Mon night, and starting Tue is a fairly dry period at least
through Thu night, and likely through Fri night for all but the
central Idaho mountains. An extended period of northerly flow will
bring below zero and single digit temperatures to the forecast area
during the overnight hours. Temperatures through Wed will be at
least 10 degrees colder than average lows and highs. The airflow
shifts to more westerly Wed night, and the warming trend starts to
increase in magnitude. A weak trough may return in the last 24 hours
to the central Idaho mountains. Strong wind should end during the
day Mon, and then be light. The dominating high pressure should
allow late night and morning fog at least through Wed night.
Messick

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.AVIATION...Mid-level or lower CIGs expected to re-develop from west
to east and north to south during the morning to early afternoon. SN
eventually develops, again slowly from west to east and north to
south, with KSUN the first early this afternoon, but most others
during the evening. For KBYI and KPIH, RA will mix with the SN, so
biggest impact to CIG and VSBY should be KIDA, KDIJ, and KSUN during
the afternoon. But even KPIH and KBYI will have to cope with an IFR
threat during the late night hours tonight into Sun morning.
Moderate to strong wind will be developing at the end of the 12Z TAF
period, then be stronger Sun afternoon. Messick

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 6 PM this evening to 10 PM MST Sunday
for IDZ060-062>064-066.

Winter Weather Advisory from 6 PM this evening to 3 PM MST
Sunday for IDZ071>073.

Winter Weather Advisory from 6 PM this evening to 10 PM MST
Sunday for IDZ061-065.

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