Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 241059

Area Forecast Discussion
National Weather Service Salt Lake City UT
459 AM MDT Fri Mar 24 2017

.SYNOPSIS...High pressure will build into the area today. This will
be followed by a Pacific weather disturbance late tonight through
Saturday, and another storm system during the first half of next


.SHORT TERM (Through 12z Monday)...A shortwave ridge is building
into the Great Basin the morning as the pattern amplifies due to a
deepening upstream trough. The ridge axis will be overhead around
midday before shifting into eastern Colorado this evening. This
ridge will bring dry and stable conditions to the area today with
warmer temperatures. In the meantime, a thinning stratus deck
remains in place early this morning along and near the Uintas,
Wasatch Plateau, and southwest Wyoming. These clouds should continue
to diminish during the morning hours while thin cirrus starts to
spread in from the west.

The upstream trough will continue carving south as it makes its way
inland and becomes a somewhat split trough as it crosses Utah
tomorrow. However, it will be accompanied by a plume of moisture,
bringing PWATs up to 0.4-0.6 inches, and will maintain enough energy
to produce fairly widespread precipitation across the forecast area
late tonight through tomorrow. Although the associated cold front is
not particularly strong owing to the splitting nature of the trough,
cold advection behind the trough axis will bring 700mb temperatures
as low as -7 to -8C across northern Utah tomorrow night. As such,
snow levels are expected to fall to near 6500-7000ft across much of
the area, and potentially down to around 5000 feet across northern
Utah towards the tail end of the storm tomorrow night.

Another shortwave ridge will build into the area for Sunday but
temperature will not have the opportunity to warm much above normal
with the next storm quickly approaching.

.LONG TERM (After 12Z Monday)...The next Pacific storm system is
expected to cross the forecast area on Monday. EC/GFS now show this
system moving across Utah and southwest Wyoming as an open wave
before diving southeast and closing off around the Four Corners
Tuesday morning. The system is progged to bring a decent cold front
through, with temperatures just a bit cooler in the GFS compared to
the EC given a more southerly track. Precip along the boundary
should be valley rain/mountain snow, but 700 mb temps could
potentially support snow to northern Utah valley floors with any
precip continuing into Tuesday morning. Previous model runs have
shown warmer temperatures and thus higher snow levels, so have held
off on a mention of snow along the Wasatch Front and Cache Valley at
this time.

High pressure is expected to briefly return late Tuesday into
Wednesday behind the exiting system, resulting in a lull (if not a
break) in precipitation. However, EC/GFS continue to show a Pacific
Northwest storm system diving southeast into the Great Basin
Thursday. Both show the system closing off as it moves into the
Desert Southwest Friday morning but diverge with the track it takes
afterward. GFS ultimately moves the system into northern Mexico and
Texas by Saturday night/Sunday, which would limit the potential for
precip over the forecast area after Friday. However, the latest
ECMWF tracks the system along the UT/AZ border through Sunday
morning, resulting in a longer period of precipitation. For now,
have kept chance POPs in through much of day seven.


.AVIATION...The SLC terminal will see VFR conditions through the day
with increasing high clouds. Southerly winds are expected through
the afternoon, but there is a 20 percent chance of a late shift to
the northwest between 21Z and 23Z.





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