Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 161037

Area Forecast Discussion
National Weather Service Salt Lake City UT
436 AM MDT Mon Oct 16 2017

.SYNOPSIS...A warming trend will continue through the middle portion
of the week as high pressure remains in place. The next storm system
is forecast to cross the area Friday through Friday night.


.SHORT TERM (THROUGH 12z THURSDAY)...A mean ridge will remain in
place across the western CONUS today into tomorrow, keeping dry and
stable conditions in place. Temperatures will trend warmer today,
but with weak flow continuing to provide little help with mixing,
temperatures in low-lying valleys across northern and west-central
Utah will likely remain below or near normal at best, despite H7
temperatures near 6C.

The ridge will flatten tomorrow night into Wednesday as a very weak
disturbance ripples through the area. Winds will increase slightly
on Tuesday which would help bring a bit more mixing and thus
additional warming for Tuesday afternoon despite increasing high
clouds. The GFS and, to a larger extent, the NAM both strengthen a
portion of this disturbance across southern Nevada and Arizona which
both models suggest could bring some precipitation to southern Utah
Wednesday afternoon and evening. The EC remains the drier solution,
although it does also show a weak vort max associated with this same
feature. Continuing to trend the forecast closer to the EC at this
time, but do have some increased cloud cover across southern Utah
for this timeframe.

.LONG TERM (After 12z Thursday)...As the flow becomes more
southwesterly ahead of an amplifying trough feature, the warm
advection taking place will come to an end with a cold front pushing
into Utah Friday afternoon.

With the latest runs of both the GFS and the ECMWF in the extended,
one difference is the location and place of the upper level trough
as it swings through the Great Basin and into Utah. With the latest
available guidance, both models have the system a bit farther to the
north as we enter Friday. Also, this trough has become more
amplified and therefore is ejecting to the east quicker with each
model run. Another point to note is the decrease in moisture with
the latest model guidance. Still, a large area of Utah and southwest
Wyoming will see precip late Friday through Saturday, the amounts
are decreasing at this time.

The cold front is trending slightly warmer, with 700mb temps cooling
to near -6C into Saturday morning. The cold air is being displaced
by the better available moisture, so this will be something to
watch. As the front exits to the east later Saturday, a rapid
warming trend of high pressure builds in Sunday. Temperatures will
warm back to near normal by Sunday.


.AVIATION...Continued VFR conditions at KSLC terminal with little
operational concerns during the TAF period. Prevailing clear skies
with some thin high clouds increasing during the day Monday.
Southeasterly winds expected to shift to the northwest by 18z.


.FIRE WEATHER...High pressure will remain in place into the latter
part of the week, interrupted only by a very weak but dry weather
disturbance Tuesday night into Wednesday. Temperatures will climb
gradually during this time with humidities remaining on the low
side. Overnight humidity recoveries may be poor in some mid-slope
and higher elevation sites especially across the southern and
central Utah. After generally light winds through Wednesday, south
winds will start to increase Thursday afternoon into Friday ahead of
a cold front. This cold front is expected to sweep across the fire
district Friday afternoon through Friday night and bring a quick
burst of valley rain and mountain snow to mainly northern and
central Utah.





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