Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
942 am MST Friday Feb 27 2015
Synopsis..a developing winter storm system will affect much of
the southern and central Great Basin this weekend. A second storm
will follow the weekend storm early next week.
Discussion...a moist northwest flow aloft remains in place over the
eastern Great Basin this morning...with weak disturbances embedded
within this flow. Warm advection is strengthening at 700mb...and is
associated with a narrow band of showers crossing northern Utah at
this time. Enough cold air aloft remains in place to keep the
airmass unstable enough to generate a few showers throughout the
forecast area this afternoon. Otherwise...weak shortwave ridging
will develop late this afternoon and into this evening as the next
storm system currently over the Pacific northwest carves south along
the West Coast.
The storm system will continue to slowly track south along the West
Coast and elongate northeast to southwest as it starts to split from
the mean flow. This storm is still expected to bring a prolonged
period of precipitation to the forecast area as it slowly crosses
the Desert Southwest through the weekend. Ample precipitation is
still forecast mainly across southern and portions of central
Utah...although there is still some uncertainty regarding the
northern extent of heavy precipitation. A winter weather watch
remains in place for the central and southern mountains...and main
focus on this shift will be deciding on any upgrades/additions...a
dilemma given greater than usual model spread this close to the
Also of concern will be the easterly gradient that is
currently in place across southwest Wyoming and into northern Utah.
Models show this gradient tightens a bit tonight which could produce
some locally enhanced canyon winds along the Wasatch front. These
winds will not be very strong tonight and will not result in any
issues as the push remains quite shallow. By tomorrow night...there
will be more support at 700mb which could lead to stronger winds.
However...model trends with the latest runs are less optimistic
that a significant event will occur.
Made mostly minor updates to reflect latest observational trends for
the remainder of the morning and to lower probability of precipitation slightly across the
south for this afternoon.
Aviation...isolated showers continue to move toward the slc
terminal from the northwest this morning. Isolated showers again
possible this afternoon. Ceilings will remain around 6000 feet above ground level
this afternoon with winds generally out of the southwest.
Utah...Winter Storm Watch from this evening through Sunday evening for
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