Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 241622

Area Forecast Discussion
National Weather Service Salt Lake City UT
1022 AM MDT Sat Jun 24 2017

.SYNOPSIS...High pressure will keep dry and warm conditions over
the forecast area through Monday. A series of weak storm systems
will impact primarily northern Utah Monday night through Thursday
before high pressure returns for the end of the upcoming week.


.DISCUSSION...The forecast area is currently under northwest flow
aloft on the front side of a ridge centered over California.
Conditions are generally tranquil over Utah and southwest Wyoming
with clear skies and light winds. Smoke associated with the Brian
Head Fire will continue to impact visibilities and have retained
mention in the grids. Northern Utah and southwest Wyoming will
see slightly warmer temperatures compared to yesterday, with maxes
running just a few degrees above seasonal normals. Meanwhile, the
very warm conditions will continue over southern Utah with maxes
running 10-15F above seasonal normals. This will continue to
result in dangerously warm conditions over far southwest Utah,
where an Excessive Heat Warning remains in effect through Sunday,
and will likely be extended into Monday with the afternoon

The ridge will make its way east over the next couple of days,
with the axis moving overhead by early Monday and east of the area
by Monday afternoon. Little change is expected in the already
very warm temperatures over southern Utah, but by Monday maxes
over northern Utah and southwest Wyoming will be running up to 15F
above climo. The switch to southwest flow as the ridge moves east
of the area Monday afternoon will allow for some moisture to make
its way into the forecast area, allow for the threat of high-based
convection over the higher terrain during the afternoon.

The first in a series of weak troughs is progged to move across
northern portions of the forecast area beginning Monday evening,
bringing a cold front into northern and central Utah. The front
will be on the dry side, but there should be enough associated
instability to maintain at least isolated showers and
thunderstorms over northern Utah into Monday night. Maxes Tuesday
will be noticeably cooler, about 5F below Monday`s values over
southern Utah and more like 10F below those values over northern
Utah and southwest Wyoming. Though temperatures will still be
above climo across the forecast area, this will bring relief from
the dangerous heat to southern Utah.

A second weaker cold front is expected to move into northern Utah
Tuesday night into Wednesday in association with a second weak
trough. A slightly stronger third trough will bring one last front
through much of the forecast area Wednesday night into Thursday
before high pressure returns for the end of the upcoming work

No updates expected to the forecast this morning.


.AVIATION...The SLC terminal will see VFR conditions and clear
skies throughout the day. Light winds are expected to become
prevailing northwesterly by 18Z.


.FIRE WEATHER...High pressure will continue to build over the
district through Monday, resulting in light winds and mostly clear
skies. Hot conditions will persist over southern Utah, resulting
in a Haines index of six. Temperatures will warm over northern and
central Utah Sunday into Monday, allowing Haines indices of six to
spread over the much of the rest of the district by Monday

The ridge axis will shift east of the area by Monday afternoon
ahead of an approaching storm system. The approach of this system
will result in increasing southwest winds over southwest Utah.
Combined with the already dry conditions, this has the potential
to produce critical fire weather conditions. This increasing flow
will also draw some high-based moisture northward into the
forecast area, resulting in isolated afternoon and evening
thunderstorms over the higher terrain.

The first in a series of weak storm systems will cross northern
Utah beginning Monday night, bringing through a weak cold front
and allowing for the potential of high-based thunderstorms across
northern Utah into early Tuesday. Additional systems will bring
cold fronts through Tuesday night and Wednesday night and will
maintain enough moisture and instability to keep the threat of
thunderstorms over the higher terrain of northern Utah in the


UT...Excessive Heat Warning until 10 PM MDT Sunday for UTZ019.




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