Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Salt Lake City Utah
927 PM MDT sun Apr 20 2014
Synopsis...a weak storm system will move slowly out of the
region tonight. A warm southwest flow will develop Monday.
A Cold Spring storm will impact the area Tuesday and Wednesday.
Discussion...weak convection remains across the southern County Warning Area this evening
along the weak stalled surface boundary that pushed through the County Warning Area
today drying the northwest. Expect this to pretty much dissipate
over the next few hours although clouds and weak light showers could
linger through the night. Even so...the chance of measurable rain
from these lingering showers will be near zero.
The short wave ridge axis moving into the Great Basin at this time
will shift rapidly east by Monday afternoon as a mild southwesterly flow develops.
The remains of the surface boundary lift back north as a weak warm
front and models continue to develop convection in association
with this feature and increasing upper level lift across the northern
Great Basin including portions of northern Utah late Monday afternoon through the
evening. Models also indicate convection developing over the terrain
tomorrow afternoon as well from the southern mountains northward. Dont expect much in
the way of precipitation from this but gusty winds are possible.
Increasing south winds and a mild airmass away from the convection
should bring a warm day Monday area-wide. South winds increase Monday
night into Tuesday ahead of a deep Pacific trough. New 00z NAM remains a bit
slower with the cold front keeping it west of slc until after 00z Wednesday
but does develop a very tight Post frontal surface gradient across the
Salt Flats that crosses the Wasatch front by 03z. This would be
too slow if the new GFS and ec remain consistent with their previous
runs. The NAM also continues to indicate very strong southerly
winds across much of the County Warning Area ahead of this front during the day
Tuesday so current high wind watch appears on track.
This system is not terribly moist but it should bring a period of
Post frontal precipitation to the Wasatch front and adjacent mountains new
NAM is forecasting about 1/3 to 2/3 of an inch of water in this
area and this would be all snow in the mountains so marginal advisory
level amounts are possible if this is right. Still dont expect a
major impact from this although is could affect the Wednesday morning
commute over parleys from the Park City area. The airmass is
forecast to get cold enough for snow to the Wasatch front valley
floors but dont anticipate any real accumulation below about 5500
This cold airmass could send temperatures locally below freezing along
the Idaho border Wednesday morning but probably not into the 20s.
Increasing clouds with a warm front Wednesday night could preclude temperatures
dropping any lower Thursday morning in this area but some of the
normally colder locations across the central and southern County Warning Area could dip
below freezing Thursday morning.
Updated earlier to lower probability of precipitation below slight chance mention across
the northern County Warning Area the rest of this evening and sky cover in these same areas
after midnight once the cirrus plume moves east. No other changes
Aviation...the slc terminal will see VFR conditions throughout the
taf period with any ceilings well above 7000 feet. Southerly winds will
prevail tonight and will remain southerly through the day Monday.
Winds could become gusty after about 17-19z. There is a 30 percent
chance of a switch to northwest around 21-22z.
Utah...high wind watch from Tuesday morning through Tuesday evening for
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