Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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315
FXUS65 KSLC 242203
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
403 PM 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.

&&

.SHORT TERM (Through 12Z Tuesday)...A ridge of high pressure aloft
will drift towards our area tomorrow into early Monday, bringing
a warming trend for nearly the entire forecast area. The Wasatch
Front should reach the upper 90s by Monday, with KSLC perhaps
reaching 100. The one exception will be far southern Utah where
temperatures will actually decrease a few degrees in response to
slightly cooler 700MB temps in that area. Have opted to not
extend the Excessive Heat Warning for far southwest Utah beyond
Sunday as the HeatRisk guidance suggest the impacts from heat will
diminish by Monday. Meanwhile, the HeatRisk readings increase for
the rest of the state Monday, but do not approach critical
thresholds.

The flow aloft becomes southwesterly by mid-day Monday as a weak
upper-level trough approaches the Great Basin. This trough will
bring gusty winds to the West Deserts of Utah, with breezy winds
elsewhere. Deep mixing with these winds will aid in warming
temperatures for most areas. Also, dry conditions will linger for
most of the area, with dangerous fire weather conditions as a
result. Mid-level moisture increases across Central and Northern
Utah by late in the day and into Monday evening. Combined with
synoptic support from the trough, we could see a few showers and
thunderstorms develop late Monday. The most favored locations
would be in the mountains, though cannot rule out a few over
Northern Utah valleys as well. Any that form would be of the
high-based variety, with little if any rain expected. Instability
is currently progged to be quite weak, and currently looks to be
the limiting factor for convective development. Nonetheless, will
need to keep an eye on this threat.

.LONG TERM (After 12z Tuesday)....Initial trough is expected to
exit the area by Tuesday morning. However, the next weak system in
the series is progged to quickly follow on its heels for Tuesday
night/Wednesday, bringing another weak front into northern Utah
and keeping a threat of high based showers/thunderstorms over the
higher terrain.

Global models bring one last system by for Wednesday night
into Thursday. This system is a bit stronger in the GFS compared to
the EC and its solution brings slightly more significant cooling
(down to as low as -7C at 700mb compared to -9C or -10C over
northern Utah in the EC) and a bit better shot of precipitation. GFS
has been a bit more consistent to this point so have raised POPs
slightly and cooled temperatures just a bit for Thursday.

Behind the last system of the series, high pressure is expected to
return to northern Utah and southwest Wyoming, bringing a warming
and drying trend through day seven.

&&

.AVIATION...Clear skies and VFR conditions are expected to
prevail at the SLC terminal through this evening. Light northwest
winds will become southeast by 04z this evening.

&&

.FIRE WEATHER...Hot and dry conditions continue Sunday as a ridge of
high pressure aloft drifts into Utah from the west. Temperatures
will warm most locations, except far southern Utah which will
actually cool a few degrees.

The approach of a weak mid-level disturbance on Monday is expected
to kick up west to southwest winds across southwest Utah Monday
afternoon. Combined with continued low RHs and Haines index of 6
overspreading most of the state, have issued a Red Flag Warning for
the valleys and mountains of southwestern Utah.

The trough may also trigger isolated high-based showers and perhaps
a few thunderstorms. Current projections suggest any thunderstorms
would be mostly dry. Also, a cool front will bring a shift to
northwesterly winds Monday night, while southwesterly winds continue
Tuesday for southern Utah mountains and southeast Utah. Will keep an
eye on the situation as the warning may need to be expanded
northward Monday due to thunderstorm potential and eastward Tuesday
with lingering critical conditions in some zones.

&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Red Flag Warning from noon to 10 PM MDT Monday for UTZ492-493-
     495>497.

     Excessive Heat Warning until 10 PM MDT Sunday for UTZ019.

WY...None.
&&

$$

SHORT TERM...Van Cleave
LONG TERM...Traphagan
AVIATION...Dewey

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php



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