FXUS65 KSLC 181150

Area Forecast Discussion
National Weather Service Salt Lake City UT
450 AM MST Fri Jan 18 2019

.SYNOPSIS...The current winter storm impacting Utah will exit the
state by early this afternoon. High pressure aloft will settle
over the area this weekend. A new storm system will enter the
Great Basin for Sunday night through Monday. This storm will
bring widespread precipitation to the area to begin the week.


.SHORT TERM (Until 00z Tuesday)...The shortwave that brought
widespread moderate/heavy precip to the state yesterday will
continue southeast out of Utah by early this afternoon. Convective
showers have become energized once again with the arrival of the
mid-level cold pool over northern Utah. This convection should
persist through the morning, then gradually dissipate this
afternoon as the mid-levels warm/dry ahead of the upper ridge
advances toward the western Great Basin.

Showers and thunderstorms along the leading low-level baroclinic
zone associated with the mid-level shortwave sit near the Arizona
border early this morning. The remaining showers/thunderstorms
along this boundary should move south and east out of Utah with
the baroclinic zone over the next couple of hours.

The aforementioned upper ridge currently along the west coast will
expand east across much of the western CONUS this weekend. A
rather substantial moisture plume upstream from the ridge will
advance along the northern periphery of the ridge over the
northern Rockies/northern Great Basin. Moist low-level warm
advection will develop along the Idaho border early Saturday.
This thermal advection will lack any significant mid-level
support to sustain deep layer lift. Will still put a mention of
light precip across far northern Utah through Saturday, though
suspect that extensive cloud cover will be all that results from
the moisture plume.

The next Pacific mid-level trough will reach the Pacific Northwest
coast Sunday evening, then continue southeast into the Great Basin
as a somewhat positive-tilt trough late Sunday night/Monday. The
strongest low-level forcing with this feature looks to focus on
west-central through southern Utah along the near 700mb baroclinic
zone. Vorticity lobes moving through the base of the upper trough
will interact with the baroclinic zone to place the heaviest
precip across central and southern Utah. Northern Utah will still
receive sufficient lift from the weaker northern portion of the
trough, though precip amounts will end up somewhat lighter than
points to the south.

.LONG TERM (After 00Z Tuesday)...On the backside of the trough
sliding through Utah and the Four Corners area, the cold core aloft
will continue to filter in under a northwest flow pattern. Lingering
mountain snow showers are possible into early Tuesday. With ridging
to the west, warm advection will begin to take place with moderate
moisture present.

Through the remainder of the week several short waves will
transverse the forecast area each with fairly weak dynamics and
moisture, and on top of that poor model to model agreement. Any
available moisture and convergence may lead to mountain snow showers
with little accumulation through the weak. No big notable storms to
speak of during the remainder of the week ahead however.


.AVIATION...Northwest winds will prevail at KSLC through
the day today. Brief periods of MVFR rain/snow is expected in the 12-
17z window with cigs obscuring the mountains. Improvement to VFR
conditions is expected by mid afternoon.


UT...Winter Storm Warning until 5 PM MST this afternoon for

Winter Weather Advisory until 5 PM MST this afternoon for UTZ001-

Winter Weather Advisory until 11 AM MST this morning for UTZ517-

WY...Winter Weather Advisory until 5 PM MST this afternoon for WYZ021.




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