Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
933 am MST Friday Dec 19 2014
Synopsis...high pressure aloft over Utah will yield to an
increasingly moist west to northwest flow beginning tonight. An
active period of valley rain and mountain snow will result from
this moisture over the weekend through early next week.
Discussion...shortwave ridge building over Utah this morning with
700mb warm advection strengthening through around midday. Middle/high
clouds increasing from the west but low stratus that formed late
last night over eastern/southern valleys remain in place and will
only slowly burn off later today. Weak echoes noted on kmtx likely
not resulting in any measurable precipitation this morning...but
virga/flurries are possible.
Ridge will quickly shift east this afternoon as weak splitting
shortwave trough currently over Oregon/cal approaches the area.
Transition to cold advection this evening with this trough...with
precipitation filling in over mainly northern/central portions of
the forecast area through tomorrow morning as additional
disturbances cross the area. Precipitation should remain relatively
light owing to weak dynamics. Snow levels may briefly touch the
valley floors overnight.
Models still trending for a prolonged and very wet period this
weekend with warm advection occurring in conjunction with an
atmospheric river event over the north. A Winter Storm Watch is in
place for the northern mountains where GFS and NAM are both
generating over 2 inches of water.
Updated forecast mainly to remove fog mention for this morning and
to adjust sky cover.
Aviation...ceilings are expected to remain above the 6000ft above ground level level
at the kslc terminal through the day. Southeasterly to southerly
surface are expected to prevail through the day as well...although a
30 percent chance exists these winds will become light and variable
and or a light westerly in the 20-00z window.
Utah...Winter Storm Watch from late Saturday night through Monday
afternoon for utz007>010.
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http://weather.Gov/saltlakecity (all lower case)
For frequently asked questions about the area forecast discussion
http://weather.Gov/saltlakecity/general/afd_faqs.Php (all lower case)