Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 172145
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
345 PM MDT Sat Jun 17 2017

.SYNOPSIS...High pressure will build over the Great Basin
beginning Sunday, bringing very hot and dry weather to the region
beginning Monday and continuing through late in the week.

&&

.SHORT TERM (Through 06Z Wednesday)...Cold front is near the UT/AZ
border this afternoon, having made its way through most of the
forecast area. Over northern Utah and southwest Wyoming maxes are
running 5-7F below what was observed yesterday, near or just below
seasonal normals. Elsewhere across the state, maxes are similar to
yesterday, up to 10F above seasonal normals. Some cumulus and mid-
level cloudiness is hanging on over northern Utah and southwest
Wyoming, and some cumulus clouds have also developed just behind the
boundary over southern Utah.

The axis of the broad ridge off the Pacific coast is expected to
move onshore over California by tomorrow morning. This ridge will
build over the West through the middle of the upcoming week,
resulting in generally dry and stable conditions with light winds.
It will also result in significant warming of temperatures over the
forecast area, particularly over southern Utah where these
temperatures will be dangerously hot. Have upgraded the going
Excessive Heat Watch to an Excessive Heat Warning for Dixie and the
Lake Powell area and to a Heat Advisory for the other areas
previously covered by the watch. Some moisture will make its way
into the ridge by Tuesday which, with the warm temperatures, will be
enough to produce a few high based showers and thunderstorms over
the higher terrain.

.LONG TERM (after 06z Wednesday)...Continued high pressure remains
in place through mid-week, with upper level temperatures
surpassing 14C (700mb). Across southern Utah, hot temperatures are
expected to continue through Thursday and some areas, into Friday.
Northern Utah will see some relief, though gradual, as the week
continues.

As the ridge begins to break down Wednesday, a short
wave is introduced into the zonal flow pattern to move through
northern Utah through Thursday morning. With this feature,
advertised by the global models, an increase in low level moisture
is also evident and a convergent zone sets up across central
Utah. With the warm temperatures, potential for afternoon
thunderstorms and showers are possible, and have kept a mention in
the forecast during the later part of the week.

Westerly flow aloft settles in through late Friday before an upper
level trough is introduced by the GFS in the Pacific Northwest.
The GFS has a 700mb baroclinic zone that pushes through northern
Utah with a cold front Saturday that will cool temperatures aloft from
near 13C to 6C, while the ECMWF does not seem to resolve this
feature until much later in the weekend and keeps it farther
north.

&&

.AVIATION...Northerly winds are expected to persist at the SLC
terminal through the evening hours. The shift to southeasterly
drainage winds is expected to be delayed a bit tonight to between 05-
07z with a 25 percent chance of being even later. Otherwise, VFR
conditions under mostly clear skies will prevail.

&&

.FIRE WEATHER...Temperatures are noticeably cooler over northern
Utah today behind a cold front that has pushed through the district
today, near normal for this time of year. Winds have become a bit
gusty in the Uinta Basin and Castle Country, but relative humidity
values remain above red flag criteria.
Tomorrow`s temperatures will warm slightly over northern Utah but
over central and southern Utah high temperatures will be near or
slightly below values observed today due to the influence of the
cold front.

High pressure will build over the area beginning tomorrow, resulting
in very hot temperatures across the district by Monday.
The ridge will persist through the middle of the week, resulting in
generally dry and stable conditions with light winds. The ridge is
expected to weaken by Thursday as a mostly dry cold front moves
through the district.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Heat Advisory from noon Monday to 10 PM MDT Thursday for UTZ013-
     020.

     Excessive Heat Warning from noon Monday to 10 PM MDT Thursday
     for UTZ019-021.

WY...None.
&&

$$

SHORT TERM/FIRE WEATHER...Traphagan
LONG TERM...Dewey
AVIATION...Cheng

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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