Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 201629

Area Forecast Discussion
National Weather Service Salt Lake City UT
1029 AM MDT Fri Oct 20 2017

.SYNOPSIS...A storm system will sweep east across the Great Basin
through this evening. An associated strong cold front will bring
substantially colder temperatures to Utah through Saturday. High
pressure will return for the first half of next week.


.DISCUSSION...Cold front moving across northwest Utah this morning
with wind gusts over 45 mph near Wendover. This front will reach
the northern Wasatch Front by 11 AM, SLC by noon, and to a
Duchesne/Cedar City line by 3 PM this afternoon. South winds have
increased temps ahead of the cold front so have adjusted
accordingly in latest updated forecast.

Winds across southwest and west central Utah have been 20-30 mph
with gusts near 40 mph already. These winds are expected to remain
at these levels or begin to lower some this afternoon as the
strongest 700 mb winds are currently over this area but will drop
off some this afternoon as the 700mb winds relax.

Have backed off on the slight chance of showers over the Wasatch
and Uinta Mountains for this morning as the radar is showing all
showers are post frontal.

The latest satellite shows that the inflection point in the cloud
shield where the best subsidence is located is right along the
NV/ID border. This indicates that the best dynamics are northeast
of this point and consequently the best area for precipitation.
Fortunately, there is a secondary cold pool at 500mb and some jet
dynamics to help create lift in the wake of the cold front this
afternoon to create a threat of showers. However, confidence is
waning some for how much shower activity will occur but left the
forecast PoPs for this afternoon in place.

One other area that winds will be strong this afternoon will be
across the southern tier. Wind gusts in excess of 40 mph are
likely as the 700mb winds are forecast to be about 40-45 kts.


.AVIATION...Winds at the SLC terminal are expected to switch to the
west-northwest with a cold front around 1730-19Z. These winds may
have a crosswind component (i.e.- around 270-300 degrees) through
20-21Z, before turning more northerly. Ceilings will lower
through the day with rain showers increasing across northern Utah,
There is a 30 percent chance of ceilings remaining above 7000 ft.
There is also a 20 percent chance of MVFR conditions in rain
between 19Z and 23Z.





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