Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 231011

Area Forecast Discussion
National Weather Service Salt Lake City UT
411 AM MDT Fri Sep 23 2016

.SYNOPSIS...A cold and moist storm system will impact Utah and
southwest Wyoming through today. High pressure will bring a drier
and more stable airmass for the weekend through the first part of
next week.


Water vapor loop shows a closed low nearing west central Utah.
MDCARS wind observations show a 120kt-155kt cyclonic jet from the
west coast into southwest Utah. GOES/HRRR/00Z KSLC RAOB indicate
the precipitable water value ranges from 0.15"-0.30" southern
mountains to 0.55"-0.90" northern and eastern valleys.

A damp and cold day is forecast for the north today as the cold
advection is maximized through the morning. Forecast highs are
near record low for max temperatures today. Snow levels near
7kft during the morning.

Lake induced CAPE will likely rise to between 500J/KG and
1000J/KG as seen on modified BUFKIT forecast soundings for a GSL
temperature of 62F. Thus areas southeast of the lake will likely
see more persistent shower activity tonight. Elsewhere
precipitation will be tapering off due to rising heights and
warming mid levels.

Last of the shower activity will wane tomorrow. Thereafter a
warming and drying trend can be expected.

Gusty west-northwest winds will occur today, most notably across
the west desert. Tomorrow the threat shifts to the canyons of
southern Utah as a northerly pressure gradient develops.

High amplitude ridge builds in over the region Sunday through
early next week. The surface high is quite strong at 1022 mb over
northern Utah Sunday while its about 1014 mb across the southern
tier. This 8mb northerly surface gradient will bring locally
breezy winds over southern portions of the CWA as well as keep
temperatures on the cool side at about 4-8 degrees below normal.
Temperatures will moderate by about 3-5 degrees by Monday and
another 3-5 degrees by Tuesday which will then be near normal.

The GFS has now gone towards the old 12Z EC solution by midweek by
developing a closed circulation which originates at the base of the
trough early Sunday over New Mexico and drifts southwestward to Baja
by Wednesday before tracking north and losing its identity. However,
by Wednesday it has tapped moisture and the PWs of 0.75 of an inch
are brought northward to the southern tier and into central and
northern Utah by Wednesday night. Since the EC and the EC ensemble
both show this meandering circulation as well have thrown some low
pops into the southern mountains Wednesday morning and afternoon and
into the central mountains Wednesday afternoon. After midnight and
into Thursday have added pops mainly to the higher terrain and
points east of the I-15 corridor. By Friday afternoon all but a few
stray showers are predicted as the moisture moves east.


Although rain has ended at the SLC terminal at 10Z with CIGS above
OVC070, the rain will move back in between 13 and 14Z and it is
expected to cause visby to fall to MVFR conditions and CIGS to
near BKN020. There is a 40 percent chance that CIGS remain above
BKN030 and visby P6SM. Winds should remain southeast this morning
and not likely shift to west northwest until 21Z although this
occur earlier than forecast.


Yesterday`s ERC values were below the 50th percentile across the
south, while several stations across the Uinta mountains were
closer to the 75th percentile.

A cold wet storm system will continue to bring periods of valley
rain and mountain snow across the north today, while southern Utah
dries out. Winds will be somewhat gusty across much of the area
today, and the south tomorrow. Snow Levels are likely to fall to near
7kft today.

A drying and warming trend is expected to begin this weekend
lasting into next week.


UT...Winter Weather Advisory until 10 AM MDT Saturday for




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