Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 142139

Area Forecast Discussion
National Weather Service Salt Lake City UT
339 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.


.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

.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

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


.AVIATION...VFR conditions will prevail at KSLC through the TAF
period. Gusty northwest winds will persist into the evening hours
before diminishing. There is a 20 percent chance that the winds
will reach Airport Weather Warning criteria before 0300 UTC.
Showers will continue across the area through the evening and
there is a 30 percent chance that erratic outflow winds will
impact the terminal through 0600 UTC. The switch to southeast
winds is expected to occur between 0900-1100 UTC.


.FIRE WEATHER...Critical fire weather conditions will continue
through Monday evening across southwestern Utah as gusty south
winds persist ahead of a surface cold front positioned across
central Utah and RH has fallen into critical levels. A Red Flag
Warning remains in effect for Fire Weather Zone 497.

Across northern Utah, where the cold front has passed, there is
the potential for showers and isolated thunderstorms to produce
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.

Heading into tomorrow afternoon, the surface cold front will
remain stationary across central Utah. Dry and breezy winds will
develop across southwestern Utah once again, but lighter wind
speeds will keep conditions below critical status.

Across northern Utah, cool and stable air will keep temperatures
on the cooler side. Scattered showers and thunderstorms will
develop across the higher terrain, with a few storms potentially
producing wetting rains. High pressure will begin to build across
Utah Wednesday into Thursday with less storm activity expected
across much of the state. High temperatures will warm back to
seasonal normals.


UT...Red Flag Warning until 8 PM MDT this evening for UTZ497.



SHORT TERM/FIRE WEATHER...Lukinbeal/Wilensky
LONG TERM...Conger

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