Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 171041
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
441 AM MDT Thu Aug 17 2017

.SYNOPSIS...A warming and drying trend will take place across the
area through Friday. Moisture will increase again from the south
over the weekend.

&&

.SHORT TERM (Through 12Z Saturday)...Mid level ridging off the
west coast is inducing a downstream trough across the Great
Basin, the axis of which currently extends from central Utah into
southern NV. As this axis continues to weaken and move off to the
east, an increasingly dry and warm west-northwest flow will
develop across the forecast area through the remainder of the
week. Lingering moisture will maintain a threat of convection
along the higher terrain, however this activity is expected to
remain weak and fairly sparse given subsidence associated with
rising mid level heights as well as the aforementioned drying
trend.

.LONG TERM (After 12Z Saturday)...Finally starting to see better
agreement among the global models with regard to the extended
period. The ridge over the region is expected to flatten during the
day Saturday as a trough moves over the top of it over Canada. This
flow will keep the airmass on the dry side, and should limit
afternoon and evening convection to the higher terrain.

On Sunday, the trough off the California coast is expected to close
off and strengthen, shifting the flow over the forecast area to a
more southerly direction. GFS has been consistent in indicating that
this flow will draw monsoonal moisture northward for the early to
middle part of the upcoming week. This combined with weak shortwaves
moving through the flow will increase coverage of convection.
Previous runs of the EC kept the forecast area mostly dry during
this period due to a different placement of the low, which caused
the flow to tap into a drier airmass. Though the latest EC is still
drier than the GFS, especially over western Utah, it is noticeably
more moist than previous runs, so have raised afternoon and evening
POPs Monday through day seven.

Temperatures look to remain fairly consistent through the extended
period with maxes running near to a few degrees above seasonal
normals.

&&

.AVIATION...The SLC terminal will see VFR conditions throughout the
day with some scattered clouds. Southeast winds are expected to
shift to the northwest between 17Z and 19Z.

&&

.FIRE WEATHER...A dry west to northwest flow aloft will bring a
warming and drying trend to the region through the remainder of
the week. Lingering moisture will maintain a small threat for
afternoon and evening convection over the higher terrain. The
chance for wetting rains with these storms will remain minimal
however. Moisture is expected to gradually return northward
into the region this weekend through early next week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

SHORT TERM...
LONG TERM...
AVIATION...
FIRE WEATHER...

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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