Scientific Forecaster Discussion
Area forecast discussion...corrected
National Weather Service Salt Lake City Utah
1000 am MDT Sat Oct 25 2014
Synopsis...a cold front approaching Utah will generate strong
southerly winds today. The front will cross the state late tonight
through Sunday ushering in a colder airmass.
Discussion...large-scale pattern this morning indicates southwest
flow over Utah with a ridge axis over the western Great Plains and a
trough over the West Coast. Said trough will track inland
today...and associated pressure falls north of Utah will lead to a
strengthening surface gradient. This gradient...coupled with 700mb
flow to 30-40kt...will lead to increasing south winds today...the
strongest of which will exist across the western valleys of Utah.
These winds will carry the bulk of the weather concerns today...as
blowing dust and Crosswinds along east-west routes may have some
impacts on travel. A Wind Advisory is in place as a result.
Otherwise...expect another mostly sunny and warm day today before
the trough arrives. Regarding temperatures...excellent mixing owing
to the elevated winds today will aid warming...and with 700mb
temperatures still in the 7-8c range...no reason we will not
encroach on record highs in some areas again today.
A weak disturbance will lift north into Utah ahead of the main
trough this evening. Models do suggest a few weak showers associated
with this wave...but since moisture is still quite limited...doubt
any measurable precipitation will reach the ground. The cold front
associated with the main trough will arrive tonight...crossing
northern Utah mostly after midnight and pushing through the
remainder of the forecast area during the day tomorrow. A few
showers are expected across northern Utah as this comes
through...although the NAM seems to be against the idea of
measurable precipitation. Precipitation will fill in more during the
day tomorrow as the middle and upper level cold push arrives. Problem
is the trough is expected to lose amplitude as it crosses the Great
Basin...with the bulk of the upper support and thus precipitation
being confined to around I-80 north by the time it reaches Utah.
Still looking at a valley Rain/Mountain snow event with snow levels
bottoming out 5500-6500ft towards the tail end of the storm tomorrow
night. Overall not a particularly significant event in terms of
precipitation as snow amounts will remain minor. However...much
colder air will settle into the area behind the front...with
northern Utah expecting to see a 25 degree drop in maximum temperatures
between today and Monday...while southern Utah will see closer to a
15-20 degree difference. A hard freeze is possible in some of the
normally colder valleys Monday night.
No updates this morning.
Aviation...southerly surface winds will continue to increase
through the day at the kslc terminal. Have issued an Airport weather
warning for gusts greater than 30 miles per hour developing between 16-17z and
lasting through 00z at least. Afternoon gusts may approach 40 plus
miles per hour.
A cold front will pass through the terminal between 09-11z tomorrow
morning switching winds to the northwest. A 40 percent chance exists
for ceilings at or below 6000 feet above ground level thereafter through the morning hours.
Utah...Wind Advisory from noon today to midnight MDT tonight for utz003-
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