Thursday, July 19, 2018, 1:24 PM EDT
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Area Forecast Discussion
Valid At
Wed, Dec 31, 7:00pm EST
FXUS65 KSLC 191540

Area Forecast Discussion
National Weather Service Salt Lake City UT
940 AM MDT Thu Jul 19 2018

.SYNOPSIS...High pressure will remain across the region into the
weekend. Moisture will increase across the south today and move 
further north Friday into the weekend.


.DISCUSSION...A nice summer morning across the state of Utah and
southwest Wyoming this morning, under mostly clear skies and
temperatures warming into the mid 70s and mid 80s by 9 am. There
is a clear dividing line of the moisture that has parked over 
southern Utah, which sits about King Canyon to Nephi to Wellington
with dewpoints in the 50s and 60s to the south, and 30s and 40s to
the north. Precipitable water values are expected to surpass 1.25
inches to 1.5 inches in the far southwest corner of Utah. All
ingredients are pointing to an active Monsoonal storm day across
the south with our biggest concern flash flooding.

The going forecast is on point, so no updates planned at this 
time. Will focus on the developing coverage this afternoon and 
look ahead to how things play out for tomorrow. Including parts of
the previous discussion below.

An elongated upper level ridge is in place across the West this 
morning, with the center of the ridge roughly located across 
southern Nevada. The center of the ridge will shift eastward 
through the morning and into the afternoon. This will help to 
continue to draw moisture north...and also change the main storm 
motions expected with any convection today.

To set up today's convection...model guidance indicates 1000-1500
J/kg of SBCAPE will develop across portions of southwestern and
south central Utah. With little deep layer shear, the genesis of
convection will be across the higher terrain, particularly the
southern Utah mountains. Corfidi vectors trend toward a westward
drift of any convection. As this convection will be outflow 
dominant, much of the CAM guidance supports convection organizing 
into one or more main clusters on a common cold pool and 
transitioning across the axis of instability set up across the 
lower deserts of Utah. This includes southwestern and south 
central Utah. 

Given the expected convective evolution this afternoon and
evening, the elevated moisture levels, and the nature of the
terrain across southwestern and south central Utah, hoisted a
flash flood watch for these areas. Started the watch around 18Z as
convection tends to trend early for the Brian Head Burn Scar...but
the main threat for southwest/south central Utah will trend later
in the afternoon and into the evening. 


.AVIATION...Expecting VFR conditions at the SLC terminal through
the day with some scattered clouds. Southeast winds in place will
occasionally be light and variable this morning before shifting to
the northwest between 17z to 19z. 


UT...Flash Flood Watch through this evening for UTZ019-020-518.




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