Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 132203

Area Forecast Discussion
National Weather Service Salt Lake City UT
403 PM MDT Thu Jul 13 2017

.SYNOPSIS... A weak disturbance will lift slowly northward across
Utah today through Friday, bringing showers and thunderstorms to
the area. In the wake of this disturbance, high pressure will
build across the region for the weekend allowing for hot


.SHORT TERM (through 12Z Saturday)...Isolated to scattered
convection has developed across Southern Utah as expected.
Elsewhere across the state and into southwest Wyoming, storms have
been mostly limited to the terrain. Hi-res models depict this
pattern continuing into the evening, with most convective activity
dying off by mid-evening. Heavy rain and small hail are the main
threats with any of these storms.

Models show the axis of convective activity that currently
stretches from Nevada to Colorado gradually shifting
northeastward tomorrow, with drier air moving into southern Utah.
Thus, expecting decreasing coverage of storms over the southern
portion of the state, with a general uptick in coverage over the
northern and eastern portions as well as southwest Wyoming. Most
convective activity should be limited to the Wasatch and central
Utah mountains eastward, but a few storms farther west can`t be
ruled out. Threats remain the same, heavy rain and perhaps small

.LONG TERM...Going into the weekend the CWA will remain
underneath the upper-level ridge with very weak flow aloft and
moderate amounts of precipitable water. The ridge will peak in
amplitude Saturday, contributing to well above normal temperatures
and depressed convection across the region. While much of the
state will be hot, the weekend heat should remain below advisory
levels. The GFS and EC currently agree that two short wave troughs
will impact the West in the extended period. The first will cross
the PacNW Sunday while the second will be further to the south on

Neither trough will dig far enough south to displace the relatively
moist monsoonal airmass, although convection will remain depressed
on Sunday. In the wake of the Tuesday trough both the EC and GFS
indicate that a monsoon surge associated with an inverted trough
rounding the 4-Corners High will help bring PWAT values over an
inch to the UT/ID border. This will contribute to significant
thunderstorm coverage over the CWA Tue- Wed. Impacts due to heavy
rain are certainly possible next week as a result.

Mean ridging looks to continue for the remainder of next week over
the region, although the ridge in the EC ensemble mean is flatter
than the GEFS. Under this pattern, the GEFS ensemble currently
indicates that precipitation will continue to be widespread through
the end of next week.


.AVIATION...Northerly winds at the KSLC terminal are expected to
persist this afternoon with scattered clouds along the higher
terrain east of the terminal. Winds are expected to shift to the
southeast between 01z and 03z, with a 30 percent chance that the
shift occurs earlier. Outflow winds may enhance the southerly winds
from nearby storms but should not impact the airport.


.FIRE WEATHER...A slow-moving disturbance and associated
monsoonal moisture which has brought scattered thunderstorms to
Southern Utah will begin to shift northeastward tonight. This will
bring lesser coverage of thunderstorms to Southern Utah Friday,
while coverage increases for northern and eastern portions of the
state. The majority of these thunderstorms will contain wetting
rains, though a few on the northern periphery (mostly north of
Salt Lake City) could be drier. Most of the storms will be limited
to higher terrain, though a few may drift into the valleys as

Drier air begins to work into the region by late Friday, along
with a warming trend. Hot and dry conditions will continue Sunday
for the majority of the area, though winds will be light so no
red flag conditions are expected. Late Sunday and Sunday night,
there is a chance of dry thunderstorms developing over far
northwest Utah.

Another monsoonal moisture surge late Monday and Tuesday will
bring a good chance of wet thunderstorms to most of the area.




SHORT TERM...Van Cleave
LONG TERM...Jeglum

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