Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 170412

Area Forecast Discussion
National Weather Service Salt Lake City UT
912 PM MST Sat Dec 16 2017

.SYNOPSIS...An upper trough will move out of the area tonight.
High pressure aloft will build back into the area beginning
Sunday. A substantially colder storm system will arrive in Utah
for the middle of the upcoming week.


.DISCUSSION...The axis of the sheared upper trof sits along the
UT/NV border this evening with areas of light snow across nrn and
central UT east of the axis and over and west of the mtns.

A fairly tight northwesterly surface gradient sits across the CWA
and the low level nwly flow is precluding the light snow from
making it into the ern valleys.

The gradient is more northerly across srn UT and gusty downslope
winds have developed across Washington Co.

The trof will continue to shear apart as upstream ridging noses
in from the nw overnight into Sun and precip will wane. However,
even very light snow accumulation could cause travel difficulties
tonight as it will stick to untreated roads now that the sun has

Skies will be slow to clear overnight into Sun with considerable
low level moisture in place. Fog is possible in the Cache valley
if it clears in time before sunrise.

The heights continue to rise Sun thru Mon while the ridge axis
stays to our west. Warm advection northwest flow will bring
cloudiness back to the north Sun night thru Mon and could bring a
little more light snow to the mtns along the ID border.

The ridge finally moves overhead Tue aftn on its way east ahead of
the next Pac storm. This brings warming aloft and inversions will
once again begin to strengthen, however there will not be enough
time for the air quality to become poor before the next storm
arrives Wed.

Updated earlier to raise pops across the nrn CWA thru the eve to
account for the light snow. No additional updates planned.


.AVIATION...At the SLC terminal...MVFR conditions in light snow
will lift into VFR after about 05-06z as snow ends, with VFR
prevailing overnight. Northerly winds are expected to continue
through the night, but could become light and variable after about





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