Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 292319

Area Forecast Discussion
National Weather Service Salt Lake City UT
419 PM MST Tue Nov 29 2016

.SYNOPSIS...A cold northerly flow will continue through the week.
The next storm system will arrive over the Great Basin late
Wednesday night through Thursday evening.


.SHORT TERM...Low level stratus clouds are spreading into
Northwest Utah this afternoon, behind the departing trough to the
southeast. Breezy northwest winds have picked up around the state
through the day. High resolution models have hinted at potential
for some lake enhanced snow showers to develop again this evening
and spread into Tooele and the western Salt Lake Valleys for
several hours this evening. Many locations could see a quick inch
or so of snow with localized areas seeing slightly more. Low level
moisture and unstable conditions will help enable convection to
initiate over the lake. The northwest flow aloft will switch to
more westerly which should shut down the snow showers as warm
advection takes place, ending the showers well before sunrise

Weak short lived ridging Wednesday will quickly transition to
another cold trough diving south through the Great Basin. Timing
of the system late Wednesday into early Thursday could create
difficult driving conditions for the morning commute. With cold
road surface temperatures, there is a better chance for any light
snow to accumulate on roads. A rather unorganized baroclinic zone
drifts through Northern Utah early Thursday. Temperatures aloft
cool to -12C but the system looks a bit drier and the westerly
flow turns northerly. Models differ with this system as it travels
south through the Great Basin, and as such confidence is somewhat
low on precipitation chances. The EC splits the trough while the
GFS consolidates the low and cuts it off farther west over Nevada.
Since the GFS has been more consistent compared with the EC, have
leaned the forecast towards the GFS solution.

As the low sags southward, precipitation chances spread farther
south and east into Friday, and drier air moves in behind it
through northern Utah.

.LONG TERM (After 00Z Saturday)...West-east oriented shortwave
ridging builds into the Great Basin on Saturday. Warm advection is
underway on northwest flow throughout the day. Anticipate a slight
warming trend for Saturday although there should still be a fair
amount of cloud cover streaming into the ridge.

The ECMWF and GFS are in agreement that a broad trough then drops
into the western U.S. on Sunday. Leading shortwave embedded within
the broader trough moves through northern Utah on Sunday bringing a
threat of precipitation back to northern Utah and have increased
PoPs there a bit for Sunday afternoon. A stronger secondary mid
level baroclinic zone is then expected to move into Utah Sunday
night. The ECMWF is about six hours slower with this boundary than
the GFS. However...both the ECMWF and the GFS show good convergence
along this boundary. The mid level baroclinic zone has decent
frontogenesis as it moves south through the state and it appears
that it will have the potential to produce a pretty good band of
snow if current runs have a handle on its evolution.  Could also be
windy across southern Utah on Monday as southwest flow aloft
increases ahead of the approaching baroclinic zone. By Tuesday
morning the boundary will have cleared the state leaving a very cold
airmass...-16C to -18C at 700 place.


.AVIATION...VFR conditions are expected at the KSLC terminal through
the TAF period.  North winds will continue into the evening hours at
the terminal and the switch to southeast winds is expected to occur
between 0200-0400 UTC. There is a 10 percent chance that the switch
to southeast winds will hold off until after 0400 UTC. Periodic
ceilings below 6000 ft AGL will continue through the evening.





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