Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
357 am MDT Thursday Oct 30 2014
Synopsis...high pressure across the region today will shift east
tonight...allowing a strengthening southerly flow to develop
Friday. The next Pacific storm system will cross the region during
the upcoming weekend.
Discussion...an amplifying middle level ridge axis which extends
across the eastern Great Basin this morning will continue to
strengthen today before shift east overnight. Warming aloft
coupled with continued modification of a stable boundary layer
airmass will maintain a warming trend across most area
today...with maximum temperatures running roughly 10 degrees above
As this ridge shifts east...a strengthening southerly flow will
develop across the forecast area Friday into Friday night. This
flow coupled with a developing/tightening southerly gradient will
allow for windy conditions across western Utah Friday afternoon
into Friday night. Increased mixing will also allow temperatures
to warm into the 70s along the Wasatch front Friday afternoon.
A moist Pacific trough is still forecast to make its way eastward
across the region during the upcoming weekend. This trough looks
to affect the forecast area in two parts...the first coming in
the form of a leading shortwave trough which will push the cold
front through the forecast area Saturday afternoon. May see a few
thunderstorms associated with this feature during the day...with
snow levels falling to near 8000 feet by late Saturday afternoon
behind the front.
A lull in large scale precipitation is possible Saturday evening...before
the middle level trough axis swings through the area Saturday night
through Sunday. The European model (ecmwf) suggests more of a split with this
trough...with the best energy swinging through southern Utah...while
the GFS favors the north. As such have not made radical changes to
this portion of the forecast...but have maintained fairly high
probability of precipitation across the terrain through Sunday night...given a favorable
moist northwest flow regime. Colder air associated with the trough
axis will also drop snow levels to near 4500 feet across the area
Sunday into Sunday night. Assuming a moist low level
airmass...plenty of instability will exist across the warm waters
of the gsl and other large bodies of water...which will support
lake enhanced precipitation into Sunday night.
Long term (after 12z monday)...the cold core upper trough that
moved through the Great Basin over the weekend will have its axis
across southwest Wyoming through eastern Utah early Monday. The
trough will exit the forecast area by the afternoon...with lingering
instability showers across much of northern Utah and through the
central mountains. At this time will follow the slightly slower
European model (ecmwf) solution which would keep some shower activity going into the
afternoon hours for mainly northeast Utah.
High pressure aloft strengthening across the eastern Pacific early
in the week will shift inland across much of the western states
during the middle and latter portions of the week. Rather cold
temperatures brought into the area by the weekend trough will be
slow to warm as a stable anticyclonic north-northwest flow will
exist across Utah. Looking at temperatures bouncing back to seasonal or
greater readings late in the week in response to the upper ridge
shifting east into the basin.
Aviation...no operational concerns are expected at the slc terminal
through the taf period. Light south-southeast winds will take a turn
back to the northwest between 19-20z.
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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)