Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 170345

Area Forecast Discussion
National Weather Service Salt Lake City UT
945 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.


.DISCUSSION...Water vapor satellite imagery shows the cold upstream
trough crossing the Great Basin this evening while ahead of it, the
associated cold front was analyzed along a line extending from west-
central Utah through the Wasatch Plateau and Uinta Mountains at 21z.
Gusty winds remain in place ahead of, near, and just behind the
front, although the prefrontal winds have started to decouple and
speeds have trended downward over the past 1-2 hours. For now,
planning on allowing most wind highlights to expire at their
regularly scheduled time, except the San Rafael Swell and Lake
Powell zones which should see winds increase again tomorrow morning
near the cold front as suggested by the strengthening southwesterly
pressure gradient evident in models.

The surface boundary is advancing well ahead of the upper level
support, which just recently entered northwest Utah. As a result,
areas near the cold front remains dry, but precipitation is now
starting to fill in over northwest Utah. Expect precipitation to
continue spreading into the area through the late evening and
overnight hours. Valleys may see a brief period of rain, but snow
levels should drop fairly rapidly with snow being the most likely
precipitation type after midnight.

Continued cooling aloft will lead to steeper lapse rates conducive
to orographic precipitation continuing along northwest-facing slopes
through tomorrow morning and into the early afternoon hours
following the initial frontal band. In addition, with 700mb
temperatures around -12C, the airmass should be cold enough to
generate some lake-effect precipitation tomorrow morning. Valley
accumulations will be possible overnight and into tomorrow morning,
but should remain mostly light. However, some travel impacts are
expected on some of the higher passes, thus winter weather
highlights are in place for the Wasatch Range and central mountains.

Besides the aforementioned extension of the Wind Advisory for the
eastern zones, have also updated the forecast to make some minor
adjustments to PoP, Wx, and Wind.


.AVIATION...Gusty northwesterly winds will continue at the SLC
terminal through at least 04-05Z, 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...Winter Weather Advisory until 10 AM MDT Tuesday for UTZ007-008-

     Wind Advisory until 9 AM MDT Tuesday for UTZ013-021.




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