Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 162219

Area Forecast Discussion
National Weather Service Salt Lake City UT
419 PM MDT Mon Apr 16 2018

.SYNOPSIS...A Pacific trough will cross the region through
Tuesday maintaining cold and unsettled weather. High pressure will
return Tuesday night through midweek, followed by the next storm
system late in the week.


.SHORT TERM (Through 00Z Friday)...A cold Pacific trough evident
in satellite imagery and objective analysis is currently spreading
into the western Great Basin, and will continue to slowly make its
way east across the forecast area tonight through Tuesday morning.
The associated cold front is currently crossing the central
Wasatch Front and will continue to push southeast has pushed
through the northern and central Wasatch Front, and will continue
to push southeast across the area through the remainder of the
evening and overnight hours. Strong south winds will continue
ahead of this front into the early evening hours but should slowly
trend downward as the pressure gradient relaxes a bit later this
evening through tonight and the surface layer decouples. Have
maintained going wind headlines although northern warnings and
advisories may be able to be cancelled before their current 10pm
expiration time. Will need to monitor the eastern valleys where
winds may remain elevated into the overnight hours.

The trailing low level baroclinic zone will continue to push into
northern Utah this evening, and should become more active late
this evening into the overnight hours as the upper trough lifts
through the region. As much colder air continues to advect into
the region, snow levels should quickly fall to the valley floors
overnight where an inch or two of accumulation on elevated
surfaces can be expected. With low level moist northwest flow
coupled with steep lapse rates, orographic snowfall should
continue across the higher terrain along the I-15 corridor of
northern and central Utah through Tuesday morning. Additionally,
with 700mb temps forecast to fall near -12C overnight lake effect
snowfall will be possible southeast of the Great Salt Lake and
Utah Lake late tonight through Tuesday morning.

Mid level ridging will begin to build back into the region late
Tuesday before amplifying across the region Wednesday, yielding a
drying and warming trend. This ridge will shift east by Thursday
allowing for strengthening southerly flow as an upper low digs
into the western Great Basin.

Note: The KSLC ASOS temperature sensor suffered a malfunction
this afternoon and the max temperature of 80 degrees will not be
used for the climate record. The backup sensor recorded a high of
75 degrees and will be used as the official record.

.LONG TERM (After 00Z Friday)...The early part of the long term
period will feature an expansive upper level low moving progressing
eastward across southern Utah/northern Arizona. This southern track
would bring elevated chances of precip and colder air (e.g. snow
levels 5500-6000 feet) to much of southern and central Utah. Precip
chances will increase eastward during the day on Friday as the low
and associated cold pool progress eastward. The positioning of the
upper low and resultant flow regime would limit precipitation
chances over northern Utah except perhaps over portions of the
Uintas and Wasatch Back. The low will have largely moved east of the
area by Friday night/Saturday morning although there will be a final
chance of precip Friday night in easterly-flow favored areas in
eastern Utah/SW Wyoming where moist warm advective wrap-around
(although isentropic trajectories are not particularly impressive)
precip may occur.

Ridging will move in on Saturday commencing a general warming
trend, with this warmup being more noticeable in southern Utah
which will have been cooler on Friday. The ridge moves out of the
area by Sunday as decaying low amplitude disturbances cross
through the area far ahead of an amplifying upper low off the west
coast. Don`t expect much impact from these weak systems
Sunday/Monday outside of periods of increased cloud cover. The
warming trend should generally continue through the long term with
area maxes generally 5-10 degrees above normal.


.AVIATION...Strong northwesterly winds will continue behind the
cold front at the SLC terminal through at least 00-01Z and then
decrease in intensity overnight. Snow or a rain/snow mix will
develop after 05Z and quickly change to all snow. Periods of snow
will continue through 12-15Z. Up to 1 inch is expected on
untreated, grassy surfaces.


UT...Wind Advisory until 10 PM MDT this evening for UTZ002-004-013-

     Winter Weather Advisory from 10 PM this evening to 10 AM MDT
     Tuesday for UTZ007-008-517.

     High Wind Warning until 10 PM MDT this evening for UTZ003-005-




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