Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 211621

Area Forecast Discussion
National Weather Service Salt Lake City UT
1021 AM MDT Tue Mar 21 2017

.SYNOPSIS...A series of weak weather disturbances embedded in the
southwest flow aloft will impact Utah and southwest Wyoming through
Wednesday. A stronger Pacific storm system will move east across
the Great Basin Wednesday night through Thursday.


.DISCUSSION...The well-defined upper trough positioned along 130W
will continue to eject weak shortwaves northeast across the Great
Basin through Wednesday. One of these shortwaves currently along
the Utah/Nevada border will impact the forecast area through
around mid-afternoon. Anticipating more clouds than precip with
this feature as the low level air mass remains dry with little in
the way of forcing outside of the higher terrain. Still looking at
mainly isolated terrain-tied showers throughout the day, with
little in the way of measurable precip.

The eastern pacific trough will finally move inland on Wednesday.
This trough will split with the southern end of the trough
remaining the energetic portion as it tracks east through the
Great Basin. The near 700mb baroclinic zone associated with this
trough will settle into northwest Utah early Wednesday. This
boundary could become quite active in terms of convection by
afternoon as solid frontogenesis takes hold and favorable jet
support in the left exit region develops across western/northern
Utah. Organized convection will likely remained pinned across far
northwest Utah during the afternoon and early evening as the
baroclinic zone gains a more south-to-north orientation ahead of
the advancing trough.

Widespread precip will develop across mainly southern/central
Utah Wednesday night as the upper trough moves into the western
Great Basin. Increasingly strong synoptic-scale lift will develop
across southern/central Utah as the trough enters southwest Utah
early Thursday. Substantial cooling aloft will drive snow levels
lower, with most mountain and higher valley location seeing rain
and/or snow by late Thursday morning.

Up north precip will expand and become heavier during the day
Thursday. A deep surface low developing across southwest Wyoming
with a developing low-level circulation center over northeast
Utah all suggest strengthening synoptic-scale beginning early
Thursday morning. Significant mountain snows will develop across
the northern mountains by afternoon as cold air aloft moves in
with the upper trough and the mean layer flow become more
northwesterly as the low-level circulation center lifts northeast
into southwest Wyoming.

Precip should winds down Thursday night as a fairly sharp upper
ridge axis moves into western Utah by early Friday. The break in
precip will be short-lived as the next approaching, but splitting
trough arrives over Utah late Saturday.


.AVIATION...Southerly winds will become increasingly gusty today at
the KSLC terminal, with gusts exceeding 30mph most likely to develop
after 18z. These gusty winds will remain in place into this evening
before diminishing slightly. VFR conditions will remain in place,
but plentiful mid/high level clouds will be present.





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