Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 161104
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
504 AM MDT Sun Jul 16 2017

.SYNOPSIS...High pressure will remain in place across the region
over the next couple of days, resulting in continued hot
temperatures. Mid-level moisture is expected to southern Utah by
Wednesday, then progress northward Thursday, bringing increasing
chances of afternoon convection statewide.

&&

.SHORT TERM (Through 12Z Wednesday)...High pressure remains centered
over the southern Nevada and southwest Utah area this morning.
Showers continued overnight near the vicinity of the high center,
but these have been slowly dissipating over the past couple of
hours. Expect showers and thunderstorms to increase again mainly
over the higher terrain by this afternoon under a very warm airmass.

The ridge will gradually flatten this afternoon as a weak
disturbance grazes northwest Utah. This disturbance is expected to
push a weak and shallow cold front into northern Utah. Expect to see
minimal impacts to temperatures behind this front. However, a few
showers may become focused along this boundary across west-central
through northeast Utah by late this afternoon or early evening. As
such, have allowed a mention of PoPs in the forecast this evening
for the central and southern Wasatch Front and west-central and
northwest Utah.

The high center is progged to drift slightly farther east tomorrow
and again on Tuesday, but still not enough to allow significant
moisture to return to the area until midweek. As a result, expect
mainly diurnal terrain-based showers and thunderstorms each day
Monday and Tuesday with very warm temperatures.

.LONG TERM (After 12z Wednesday)...Following the recent trends in
guidance over the last several runs, not much has changed regarding
the large scale pattern evolution through Thursday. With the mean
ridge position holding pat slightly downstream in the vicinity of
the 4-corners, southwesterly trajectories look to continue to
impinge on much of the area. Relatively deep sub-trop moisture
advection across the western periphery of the high should drive a
net uptick of convection areawide (especially Wed/Thu). Focused
areas to watch during the midweek period continue to be the central
and southern portions of the forecast area where isolated heavy rain
potential will be maximized, but these details will unfold over
time.

Just how long the above mentioned ridge position will last continues
to be the primary long term forecast challenge thereafter, as
waffling from various model runs deters confidence in outcome late
week into the weekend. For this package have largely followed suit
of the ridge flattening and bulging west Fri into the weekend, with
a net drying trend from NW-SE as a result. Time will tell.

It`s the climatologically warmest stretch of the year currently, so
given the overall pattern of a western Conus ridge dominating
through day seven...feel quite confident in temps running at or near
seasonal norms across the south where moisture looks to be most
prevalent, and slightly above across the north where it most likely
will be a bit less so.

&&

.AVIATION...Operational weather concerns are expected to remain
minimal at the KSLC terminal through the valid TAF period.
Southeasterly drainage winds currently in place are expected to
switch to the northwest between 18-19z per norm. Buildups are once
again possible over the Oquirrhs, but only a 10 percent chance
exists that southerly outflows will impact wind direction in the
late afternoon timeframe.

&&

.FIRE WEATHER...Showers will gradually wane through the early
morning hours across portions of southwest and west-central Utah.
Otherwise, expect isolated to scattered showers and thunderstorms to
increase in coverage this afternoon, with the bulk of these focusing
over the higher terrain. A weak and shallow cold front will push
into northern Utah today but will bring little noticeable change.
North winds may be slightly enhanced late this afternoon and evening
across the northwestern quadrant of the fire district behind the
front. Otherwise, warm high pressure pattern will continue through
the first half of the week and continue to produce daily diurnal
mainly terrain-based showers and thunderstorms and generally light
diurnal winds. Looking for more significant moisture to spread into
the area around the middle of the week which would lead to greater
coverage of wet thunderstorms.

&&

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

$$

Cheng/Merrill

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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