Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 241139

Area Forecast Discussion
National Weather Service Salt Lake City UT
439 AM MST Sat Feb 24 2018

.SYNOPSIS...The active pattern across the western states will
continue into the first half of next week. The next storm system
will cross the area tonight through early Sunday. A new storm
system will track south in California and have minimal impact on
Utah midweek.


.SHORT TERM (Until 00Z Wednesday)...The upper level trough
entering the Pacific Northwest early this morning will continue
southeast into Utah this evening. Ahead of this feature the
developing warm advection pattenr will deepen across northern
Utah, resulting in a gradual increase in mostly light snow later
this morning. Snow will expand south and east as the upper trough
approaches, with intensities picking up as dynamic lift and
colder air aloft arrive with the trough.

Significant accumulations due to the low density of the snow are
expected, especially over/near the higher terrain. The current
suite of winter weather advisories for the north look good at this
time. Down south have pushed the start time for the advisories to
this evening from late afternoon. Dynamic and thermal support for
deep layer lift doesn`t get going until the upper trough reaches
the western border early this evening. Looking at a somewhat
shorter duration event along the I-15 corridor overnight as
dynamic subsidence along with drier air will move in quickly
behind the passing trough.

The trailing shortwave ridge will keep most of Utah on the dry
side Sunday. Backing flow ahead of the next upper trough along the
Pacific Northwest coast will bring a return to a moist warm
advection pattern across far northern Utah Sunday night/Monday.
Any precip resulting from this increasingly moist and deep warm
advection will remain primarily near the Idaho border and across
the northern Wasatch mountains.

The upper trough, unlike recent systems, will continue on a more
southerly track as it closes off over coastal California Monday
night. Precipitation for the most part will remain west of the
state closer to the now well developed upper low. The one area
that may still see some organized precip will be across west-
central through northern Utah where a deformation axis could
develop and become a focus for precip by Tuesday.

.LONG TERM (After 00Z Wednesday)...The Pacific storm system will
move east into New Mexico Tuesday night. A bit of associated precip
is expected to linger into Wednesday morning, primarily over the
central and southern mountains. The active pattern is expected to
continue through the end of the forecast period, with global models
this morning in much better agreement with regard to the timing of
various features compared to this time yesterday.

Moist warm advection will keep the possibility of some precip in the
forecast Wednesday into Thursday, though EC/GFS have backed off a
bit with regard to coverage and have lowered POPs slightly.
Temperatures are expected to warm noticeably during this time, with
maxes Thursday running near to slightly above seasonal normals.

A broad trough is progged to dive south to the Pacific Northwest
coast during the day Thursday before slowly making its way across
the forecast area Thursday night through Sunday. Best precip with
the system is expected Friday night into Saturday with the
associated cold front making its way through. EC/GFS in good
agreement with the timing and indicate that northern and central
Utah will see the majority of the snow. Have raised POPs a bit with
increasing confidence and lowered temperatures slightly, but they
will need to go quite a bit lower if guidance remains consistent in
this solution.


.AVIATION...VFR conditions are expected at the SLC terminal through
the morning with cigs remaining above 6000 feet AGL. Cigs are
expected to lower below 6000 feet during the early to mid-afternoon
with the approach of the next storm system, with snow becoming
widespread by early evening. Southerly winds, gusty at times, are
expected during the daytime hours.


UT...Winter Weather Advisory from 4 PM this afternoon to 11 AM MST
     Sunday for UTZ003-004-008>010-517.

     Winter Weather Advisory from 10 AM this morning to 11 AM MST
     Sunday for UTZ001-002-006-007.

     Winter Weather Advisory from 6 PM this evening to 6 AM MST
     Sunday for UTZ015-016-518.




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