Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 202321

Area Forecast Discussion
National Weather Service Salt Lake City UT
421 PM MST Sat Jan 20 2018

.SYNOPSIS...A Pacific storm system will slowly exit the region
tonight. High pressure will build briefly Sunday night, followed
by a weak storm grazing northern Utah on Monday. A stronger storm
is expected during the latter part of next week.


.SHORT TERM (Through 12Z Thursday)...Afternoon water vapor imagery
and objective analysis show the mid level trough crossing the
Great Basin/lower Colorado River Valley, with the associated low
level baroclinic zone stretching from southwest Wyoming into
central Utah. A circulation translating along this boundary Is
lifting through central Utah and has allowed light snow to
redevelop across portions of northern Utah, while precipitation is
more showery across central and southwest Utah. As the trough axis
continues east this evening precipitation will likely become more
orographically forced across the area. Have retained going Winter
Weather headlines for the higher terrain as well as advisories for
the Uinta Basin/Castle Country through the evening hours.
Lingering precipitation should gradually taper off overnight into
the morning hours Sunday along the higher terrain.

Mid level ridging will follow for Sunday afternoon/night, before a
progressive shortwave crosses the northern Rockies Monday. The
models have been trending further north and weaker with this
feature, and it appears the best chance for precip will likely
remain confined to the higher terrain near the Idaho border. Given
the weakening/further north trends have left PoPs in the slight
chance to low chance category for now.

.Long Term (After 12Z Tuesday)...The weak shortwave trough
continues to exit through the day Tuesday, with a slight chance of
lingering showers across far northern Utah in the somewhat moist
westerly flow. These showers end as a ridge shifts overhead late
Tuesday into Wednesday.

Southwesterly flow increases significantly late Wednesday into
Thursday, as a larger trough moves inland from the Pacific. Have
increased the wind forecast some, and it will probably need to be
even stronger in the future, especially across southern Utah for
Thursday afternoon/evening.

Models are currently in fairly good agreement about bringing the
cold front through Utah on Thursday evening, with a round of
showers continuing into Friday. Have continued to raise POPs
through this period of time, as models have been fairly
consistent. In general, this looks like a fairly quick hitting and
cold trough, with a shot of new snowfall over much of the area.


.AVIATION...Occasional snow will continue at the SLC terminal
through about 02-04Z, which may bring IFR conditions and light
accumulations on untreated surfaces. Northwest winds will likely
continue through the night, with a chance of light and variable
winds developing after 07Z.


UT...Winter Storm Warning until 5 AM MST Sunday for UTZ008>010-517-

     Winter Storm Warning until 11 PM MST this evening for UTZ006.

     Winter Weather Advisory until 11 PM MST this evening for UTZ011-

WY...Winter Storm Warning until 5 AM MST Sunday for WYZ021.




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