Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
556 am MST sun Mar 1 2015
Synopsis...an upper level trough will linger over the Great Basin
through Monday then shift east late Tuesday.
Short term (thru 00z wed)...an upper trough lays NE-SW across the
Great Basin this morning southwestward through an upper low over the
central California coast and off into the Pacific.
A strengthening jet on the southeastern side of this trough has been
generating increasing lift across Arizona with precipitation filling in under
it. This jet takes aim at southern Utah through the day as the southern end of
the West Coast trough pivots eastward backing the flow on the east side
of the trough to more southerly.
Expect precipitation to become widespread across southern Utah by late today
then gradually spread north tonight reaching all but far northwestern Utah
by Monday morning. The California low then ejects northeastward across Nevada and into western
Utah during the day Monday keeping precipitation widespread across the County Warning Area.
The airmass warms somewhat today as the southerly flow develops
with snow levels rising to around 5500 west to 6500 feet east and
remaining at about this level into early Monday. This is low enough
to put snow into the higher southwestern valleys by this afternoon and across
the higher portions of S-central Utah. This would also keep snow
above most of the eastern valleys except the price area.
Snow levels should fall to most western valley floors by late Monday
as the remains of the California upper trough arrives with a reinforcing
cold trough from the North Crossing the County Warning Area on Tuesday keeping snow
going in the northwestern valleys and most mountains
Have extended the existing snow advisories for the mountains through Tuesday
afternoon and these may need to be expanded into the northern mountains for
tonight into Tuesday. Issued new advisories for southwestern valleys and
S-central Utah above 5500 feet through Monday evening and extended the price area
through the same time. It is possible that valley advisories may
also be needed for the Wasatch front and west-central Utah for Monday
afternoon into Tuesday.
Think that other eastern valleys should stay rain until the flow veers
to westerly and then precipitation would become showery. It is possible the
Uinta Basin could get accumulating snow tonight into Monday however
and the advisory may need to be expanded into this area too.
Precipitation turns showery Tuesday afternoon as the final cold trough shifts east.
Long term (after 00z wednesday)...the last trough is expected to
exit the forecast area Tuesday night/Wednesday morning...with only a
few showers lingering into the overnight hours. High pressure is
prognosticated to build behind it and persist at least through
Friday...resulting in dry conditions with temperatures warming back
above seasonal norms.
Latest GFS indicates a weak trough grazing northern Utah Friday
night and Saturday...bringing through a cold front to curb the
warming trend. 00z European model (ecmwf) keeps high pressure established over Utah
and southwest Wyoming through day 7...and previous guidance has
indicated the same thing. Therefore...am hesitant to believe the GFS
solution and kept probability of precipitation out of the extended period. Did curb the
warming trend a bit for the upcoming weekend but temperatures should remain
Aviation...the slc terminal will see VFR conditions throughout the
day. Ceilings will generally stay above 6000 feet above ground level but will
occasionally fall below that level through about 18-19z. Winds are
expected to be generally light during the morning before becoming
prevailing northwesterly between 16z and 18z. Wind directions may
be occasionally variable early this morning.
Utah...Winter Weather Advisory until 4 PM MST Tuesday for utz010-517-
Winter Weather Advisory until 9 PM MST Monday for utz012.
Winter Weather Advisory from 11 am this morning to 9 PM MST
Monday for utz016-020.
For more information from National oceanic and atmospheric administration/S National Weather Service visit...
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)