Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 210435

Area Forecast Discussion
National Weather Service Salt Lake City UT
935 PM MST Fri Jan 20 2017

.SYNOPSIS...The active weather pattern will continue across the
region, with a series of weather systems crossing the area through
the first half of next week.


.SHORT TERM (Through 00z Tuesday)...The intensity and areal extent
of precip continue to increase across the state this evening as
the negative-tilt trough advances into the southern Great Basin.
Synoptic-scale will continue to increase overnight as deep layer
cold advection arrives and along with solid dynamic lift from the
approaching trough. The heaviest snows look to strike the southern
mountains where the strong lift will be further enhanced by the
upper divergence into the left exit region of the 140+ kt jet
pointing toward southern Nevada/western Arizona.

Widespread snow will persist through Saturday morning, then
gradually decrease as heights rise ahead of the upper ridge
strengthening along the west coast. This ridge will shift east
into Utah and continue to strengthen Saturday night/early Sunday.

The next Pacific trough will set up just off the west coast
Sunday. Downstream of this trough a fairly strong southwest flow
aloft will set up across the western Great Basin with a rapid
increase in moisture beginning late Sunday morning. The first
chance at precip will come either late in the morning or early
afternoon across southwest Utah where strong low-level warm
advection and terrain upglide with generate lift. Precip will
spread quickly to the north, but will likely remain more on the
light side until the colder air aloft and somewhat stronger
dynamic lift arrive Sunday evening.

Heading into early next week the upper trough will cover a rather
broad area extending from central Canada southwest into eastern
Pacific. The moist and cold air mass embedded within this trough
combined with weak dynamic features to lift this primed air mass
will maintain fairly widespread precip through Monday.

.PREVIOUS LONG TERM (After 00Z Tuesday)...The mid-level trough
axis will cross Utah Monday night switching 700mb flow to
northwest. Precipitation will become more confined to the
mountains and windward valleys heading into Tuesday morning as
colder air spreads into the area and snow levels lower.
Precipitation in all valleys but Dixie should be all snow by
Tuesday morning.

A cold and moist cyclonic northwesterly flow within a mean longwave
trough over the Western CONUS will keep unsettled weather over the
forecast area through at least Wednesday night. Embedded
disturbances/circulation centers within the mean trough will bring


.AVIATION...Winds at the SLC terminal should remain southerly
through at least 12Z, though there is a slight chance of variable
winds due to increased shower activity tonight. Snow showers will
increase across northern Utah through the night, but KSLC should be
shadowed for much of the overnight hours due to southerly winds.
Accumulating now will be more likely after 13-15z as winds turn more


UT...Winter Weather Advisory until noon MST Saturday for UTZ005-

     Winter Weather Advisory until 8 PM MST Saturday for UTZ007>010-

     Winter Weather Advisory until 5 PM MST Saturday for UTZ001>004-

     Winter Storm Warning until 8 PM MST Saturday for UTZ518.




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