Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 150459
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1059 PM MDT Mon Aug 14 2017

.SYNOPSIS...A cold front will push south across northern Utah
tonight then stall across central Utah on Tuesday. A second
system will cross the area Wednesday afternoon through Thursday.

&&

.DISCUSSION...A shortwave trough ejecting through the Great Basin
has pushed a cold front through northern Utah late this afternoon
through this evening. In the wake of this front, a band of showers
continues along the trailing 700mb baroclinic zone across northern
Utah. This activity will likely persist into the overnight hours
as the baroclinic zone loses momentum and eventually stalls across
central Utah overnight. Updated to increase overnight PoPs into
the scattered category across the north. Otherwise a much cooler
airmass will temporarily spread across northern and central Utah
Tuesday, before temperatures rebound during the midweek period.

.PREV DISCUSSION...

.SHORT TERM (Thru 00Z Thursday)...Water vapor imagery reveals an
upper level trough upstream of Utah positioned across central
Nevada. CVA ahead of the trough along with upper level
diffluence will allow for scattered showers and isolated
thunderstorms to develop across much of northern Utah later this
evening. Showers and isolated thunderstorms could potentially
produce locally gusty winds, acting to enhance northerly frontal
winds already in place across the west desert and in other areas
favored by northerly flow such as northern Utah county. Shower
activity will linger overnight across northeastern Utah as the
upper level trough swings through.

A cold front will remain nearly stationary across central Utah
tomorrow afternoon. This will allow high temperatures to remain on
the cooler side across the north with many locations running about
10-15F below average. The stalled front could act as a mechanism
for developing convection tomorrow afternoon, but suspect dry air
entrainment and limited instability will prevent any activity.

Shower and thunderstorm activity will decrease Wednesday afternoon
across Utah, with the bulk of any activity expected across the
higher terrain of the central and Uinta Mountain ranges. High
temperatures will warm back to seasonal normals Wednesday
afternoon.

.LONG TERM (After 00Z Thursday)...A weak vorticity lobe will track
slowly east through the somewhat moist but diffluent west-
northwest flow aloft across the Great Basin Wednesday night/early
Thursday. This feature should be able to generate enough lift for
light precip across western/northern Utah into early Thursday.
Building heights trailing this vorticity lobe will serve to limit
any subsequent convection to the higher terrain late Thursday
through Thursday evening.

A weak circulation hanging back along the central California coast
will produce a weak downstream mid-level deformation axis through
central Utah on Friday. This deformation will serve as the focus
for an expanding area of convection Friday afternoon/night. This
axis will begin to drift north as the mean layer flow backs in
response to the upper low evolving into an open trough along the
coast.

Moisture drawn northward by the now deep layer northerly flow will
concentrate across the eastern half of the state during the latter
half of the weekend. Anticipating the bulk of any convection will
concentrate across mainly northwest Utah, with some of this
activity turning back to the west along the Idaho border late
Sunday through Sunday night.

The California trough will finally lift northeast across the Great
Basin early next week. The best chance for organized convection
will remain across the western/northern portions of Utah, with
lingering terrain-based convection over the central/northeast
mountains.

&&

.AVIATION...Northwesterly winds will prevail at KSLC through the
overnight period. VFR conditions are expected as well, with a 30
percent chance of rain showers into the overnight period.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php


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