Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 141055

Area Forecast Discussion
National Weather Service Salt Lake City UT
455 AM MDT Sat Oct 14 2017

.SYNOPSIS...A strong but largely dry cold front will cross Utah
this morning with a colder northerly flow behind it. Dry high
pressure will build into the region for the first part of next
week bringing a warming trend.


.SHORT TERM (Thru 00z Wed)...The strong cold front is pushing
thru the nrn CWA early this morning and has made it to roughly a
Delta to Duchesne line at this time. A band of showers has formed
behind the front and this is currently dissipating across Utah

Instability showers in the wake of the dissipating frontal band are
filling in along the Wasatch mtns and high res guidance does
indicate showers become focused downwind of the Great Salt Lake
into the Salt Lake Valley and the adjacent Wasatch mtns this
morning ending before noon. These will likely fall as snow as
temps fall behind the front but do not expect any impact on valley
routes. Snow could briefly hinder travel early today on mountain
routes such as Parleys Summit and the Cottonwood Canyons, and also
in Park City.

Gusty northwest winds have developed behind the front and these
will spread into the eastern valleys within the next few hours.
Still looks like a period of strong gusts will impact the Castle
Country valleys in the lee of the Wasatch Plateau this morning and
have extended the Wind Advisory for this area until noon to
account for the later start.

All precip quickly ends by noon as the upper trof tracks east and
upstream ridging builds in. The airmass aloft starts warming this
aftn but the cold air that spills in behind the front at lower
levels should remain in place tonight sending temps to relatively
cold levels. Expect a freeze across the Wasatch Front tonight
including areas that have yet to freeze this fall.

Ridging builds over the CWA Sunday thru Tue morning keeping skies
clear and bringing a warming trend. Stable conditions will keep
valley temps from warming to their full potential given the
warming aloft.

.LONG TERM...(After 00Z Wednesday)...Under mostly zonal flow
aloft, the jet stream is well to our north by midweek, the
sensible weather will remain quiet through Wednesday and Thursday
before changes begin to take place. Daytime temperatures will
remain right about seasonal normal with dry conditions present
across the southern portion of the Great Basin.

Late Thursday a deepening trough begins to swing southward out of
the Gulf of Alaska and through the Pacific Northwest. While the GFS
and ECMWF have wobbled on the solution to this storm system over the
last few days, the evolving pattern remains mostly the same: an
unsettled and cold weather system will move into the Great Basin
next weekend. Details regarding the timeliness of the system
ejecting through the Great Basin and exiting (or stalling) and how
cold (or not quite as cold) continue to evolve with each model run.
With the latest ECMWF, the late week trough deepens, slows down and
forms a cut off low over the four-corners area by Saturday. The GFS
is a faster solution with a more split-like feature of the trough
quickly sliding through the Rockies. Both models indicate a fairly
wet system, although not quite as cold as the system moving thru
today. Made some small changes to the PoPs in the far extended,
mostly increasing in coverage and leaned a bit more with the EC in
the slower timing.


.AVIATION...VFR with cigs blo 6000 ft will prevail at the SLC
terminal this morning. Passing snow showers could bring brief IFR
cigs/vis until about 16z-17z. Northwest winds will prevail but
could be erratic near showers. Ceilings expected to improve above
7000 feet after 17z.


.FIRE WEATHER...A strong cold front will sweep south across the
district this morning with scattered rain and snow showers over
the north while the front remains dry across the rest of the area.
Locally strong and gusty north to northwest winds will follow the
front and continue through the morning, then diminish this
afternoon. The strongest winds are expected along the eastern
slopes of the Wasatch Plateau. Dry high pressure will build into
the district starting Sunday and continuing through Tuesday. This
will bring a warming trend but also poor clearing indices due to
the stable conditions and light transport winds.


UT...Wind Advisory until 9 AM MDT this morning for UTZ012.




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