Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
359 am MST Wednesday Mar 4 2015
Synopsis...a cool dry northerly flow will be over the area
today. High pressure will bring a warming trend through the rest
of the week.
Short term (thru 00z sun)...the axis of the deep upper trough has
moved east this morning with a cold northerly flow in place across
the County Warning Area downstream from a high amplitude ridge in the eastern Pacific.
Lingering low level moisture and instability kept a few snow
showers coming off the gsl past midnight but it appears the last
of these are moving away from the lake at this time. The clouds
over the mountains could still generate a little light snow this
morning but even these should end this afternoon as the airmass
continues to stabilize and the subsidence inversions lowers.
The cold stable airmass will hold maximum temperatures down today with highs
remaining about 10 degree below normal. Clear skies and a drier
airmass should allow overnight lows to get fairly cold again
tonight in spite of gradual warming aloft. This would be
especially the case in areas with snow cover.
The eastern Pacific Ridge shifts slowly inland through the end of the week
gradually warming the airmass over the County Warning Area. This will bring maximum
temperatures back closer to normal Thursday and near or above normal Friday and
Sat. Skies should remain mostly clear tonight through the end of the
week with just some cirrus wafting past at times.
Long term (after 00z sunday)...large scale pattern across the
western Continental U.S. Will remain dominated by strong ridging to begin the
long term periods...with axis oriented along the western coastal
states. Upstream of this ridge global models indicate a closed low
centered near 145w...near stationary and cut off from the active
northern branch to the north...and an increasingly active southern
branch to its south. This trough looks like it will be a player
middle/late week next week across the eastern Great Basin.
Global models and ensemble guidance suggest the increasingly active
southern branch jet will aid to flatten the West Coast ridge
beginning early next week...this allowing eastern Pacific energy and
remnants of the low /or the trough itself/ to impinge on the western
Continental U.S.. still significant spread in timing and evolution of
this...but felt trending probability of precipitation up late day 7 and to climatology day 8 was
warranted as some semblance of another active period/large scale
pattern shift exists in each.
Leading up to that temperatures are expected to return to roughly 10
degrees above climatology late weekend into the early week period...with
largely clear skies dominating
Aviation...periodic ceilings at or below 7000 feet above ground level will remain the
primary operational weather concern at the kslc terminal to begin
the taf period...but expect continued thinning of this cloud deck
after 13/14z. Surface winds are expected to make a normal diurnal
switch to the northwest between 17-19z.
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)