Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
848 PM MST Friday Mar 7 2014
Synopsis...high pressure aloft building into the Great Basin
will bring warm and dry conditions statewide throughout the
weekend. The next Pacific storm system will cross the region
late Monday through Tuesday.
Short term (through 06z tuesday)...lingering weak convection
will end by midnight as a drier and stable north-northeast flow
aloft develops ahead of the advancing upper level ridge late
tonight through Saturday morning. The ridge will settle over Utah
through out the weekend...bringing significantly warmer temperatures and
dry conditions through Sunday night.
The next Pacific trough moving off the eastern Pacific is
scheduled to arrive over the western Great Basin early Monday...
then continue east into Utah by late Monday afternoon or early
Monday evening. Once again were looking as a system with good
baroclinic structure moving through the state Monday afternoon
through Tuesday. The surface cold front will reach northwest Utah
Monday afternoon...followed by good low-level cold advection
Monday evening. Precipitation will likely in increase rapidly in areal
coverage and intensity as the middle-level trough and the associated
cold pool move into the northwest quadrant of the state.
No updates planned for the short term forecast cloud cover as
sky conditions are quickly becoming most clear. Remainder of
the forecast looks fine for now.
Previous long term (after 06z tuesday)...the GFS and ec both
have a significant trough moving into the Great Basin region
Monday through Tuesday but the details are not so much in step.
The timing is pretty much in unison although the GFS may be a
little faster. The GFS has the 700mb baroclinic zone split into
two segments with the leading zone and associated surface cold
front moving across northern Utah Monday afternoon while the
second baroclinic zone associated with the cold pool aloft moves
into northern Utah about midnight Monday night. The leading edge
of the first baroclinic zone will stretch from the Uinta Basin to
Cedar City by midnight. As it looks now there will be a healthy
band of precipitation with the leading baroclinic zone with snow in the
mountains and rain in the valleys. When the second baroclinic zone
moves through this will bring snow levels to the valley floor
Monday night across the northern and the west central valleys. The
ec spreads the precipitation out evenly during this period and it
also brings cold enough 700 mb temperatures for snow to the valley floor
The trend of the models with this trough is a little stronger and
farther south but still the extreme south appears to remain dry due
to downsloping northerly winds. This will bring temperatures below
normal for northern Utah for Tuesday and Wednesday but they should
bounce right back up to above normal Wednesday through Friday.
However there is one fly in the ointment for late Wednesday into
Thursday as energy that has dropped into the back side of the trough
may end up creating a closed low over the southwest near Las Vegas.
The ec keeps it as an open wave and treks it southeast across
Arizona. However if the GFS is right then there will be a chance for
at least mountain showers over southern Utah Thursday. Have leaned
toward the ec solution for now as the trend towards a progressive
pattern would prevent the low from closing off.
Aviation...the increasingly stable northerly flow aloft will
bring clearing skies and VFR conditions through the taf period.
Light northerly winds will turn to a light southeast wind
between 05z and 06z.
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http://weather.Gov/saltlakecity/general/afd_faqs.Php (all lower case)