Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 242130

Area Forecast Discussion
National Weather Service Salt Lake City UT
330 PM MDT Mon Jul 24 2017

.SYNOPSIS...Moisture will spread northward today, then remain in
place across the region through the mid-week period. A gradual
drying trend is expected for the latter portion of the week.


.SHORT TERM (Through 00Z Thursday)...Deep moisture is currently in
place over central and southern Utah and is continuing to spread
northward. With southerly flow increasing between the trough off
the California coast and the ridge east of the area, PWs in the
1.2 to 1.4 range are expected to be across the entire forecast
area by tomorrow morning. Showers and thunderstorms have already
developed, with the best coverage over the higher terrain of
southern Utah.

Convection will be enhanced later this afternoon through the
overnight hours by a shortwave currently approaching southwest
Utah that will cause a noticeable increase in convection over that
area by early evening. The shortwave is then expected to track
northeast across the state through the overnight hours, keeping
convection going. These storms are already producing heavy rain
capable of producing flash flooding, and will continue to do so
through tomorrow. Current Flash Flood Watch covers this threat

This initial shortwave will exit during the day Tuesday, but
another will approach northwest Utah late Tuesday afternoon into
Tuesday evening, allowing for enhancement of convection in that
area. Have modified POPs to account for this. The deeper moisture
is progged to remain in place through at least Wednesday, but
without a shortwave on Wednesday convection should be more tied to
the higher terrain.


.LONG TERM (After 00Z Thursday)...A shortwave trough moving through
Nevada into SE Idaho Thursday will usher in drier mid to upper level
air in Utah. Low level moisture will continue to linger
throughout much of Utah, with PW values ranging between 0.8-1.0"
across the state. Thus, expect isolated to scattered thunderstorms
across much of Utah Thursday afternoon, with the best coverage
over and near the higher terrain. Central and northern Utah will
continue to dry out Friday, as dry air continues to stream in from
the west. The upper level ridge will shift over the Four Corner
region Friday afternoon, with an uptick in mid to upper level
moisture expected to wrap around the ridge and into southern Utah
Friday afternoon, allowing for isolated to scattered convection to
develop across the higher terrain of southern Utah.

High temperatures will be on the increase Saturday afternoon as the
ridge shifts across east-central Utah. High temperatures will run
about 5F above normal state-wide with temperatures approaching the
century mark across the Wasatch Front. Isolated to scattered
convection will once again develop across southern Utah`s higher
terrain Saturday, where mid to upper level moisture continues to
hang around, while northern and central Utah remain dry.

With minimal change to the mean ridge position through day 7,
maintained convective potential through the end of the forecast
period (PoPs trended towards climo a bit), while maintaining above
climo temps both night/day.


.AVIATION...VFR conditions will prevail at KSLC this
afternoon. After 03Z the chance of a shower or thunderstorm
impacting the terminal increases and showers/vicinity showers will
persist into tomorrow morning. Northerly winds should prevail this
evening before shifting to the southeast around 01-02Z, although
outflow will likely cause periods of erratic winds tonight.


.FIRE WEATHER...Deep moisture has spread into central and southern
Utah today and will continue northward into the entire district by
tomorrow morning, resulting in increasing coverage of showers and
thunderstorms with widespread wetting rain. A weather disturbance
will enhance showers and thunderstorms this evening through much
of Tuesday. This moisture will remain in place through Wednesday
before a slow drying trend commences.


UT...Flash Flood Watch through Tuesday evening for UTZ010-012>016-



LONG TERM..Lukinbeal/Merrill

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