Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
320 PM MST Friday Nov 28 2014
Synopsis...a mild southwest flow will continue across Great
Basin into Saturday. A cold front will drop into northern Utah
Saturday night into Sunday...with another system possible by the
middle of next week.
Short term (through 00z tuesday)...a broad low amplitude middle
level ridge which has resided across the region over the past
couple of days is gradually shifting eastward this
afternoon...allowing a mean west-southwesterly flow aloft to
overspread the Great Basin/intermountain west. This is maintaining
a very mild airmass across the region...with temperatures running
roughly 20 degrees above normal. The daily record of 66 at kslc
has already been tied this afternoon.
This west-southwesterly flow will remain in place and strengthen
overnight into Saturday...as a shortwave trough moves into the
Pacific northwest/northern rockies. Temperatures aloft are
forecast to cool during the day Saturday which will also be
reflected at the surface...however maximum temperatures are expected
to remain well above average.
A shallow cold front associated with the northern rockies
shortwave is forecast to drop southward into northern Utah late
Saturday night into Sunday morning...before stalling just south
of I-80 during the day. Moisture overrunning this stalled
boundary will bring a good chance for valley rain and mountain
snow to areas generally north of I-80 Sunday afternoon into Sunday
evening...before this boundary retreats north of the Idaho border
by Monday morning. Some mountain accumulation is
expected during this timeframe...however significant accumulations
are not anticipated.
Long term (after 00z tuesday)...the global models are a little more
in alignment for Tuesday and Wednesday...although the GFS remains
faster. Have reintroduced some low to modest probability of precipitation over central and
southwest Utah for Tuesday afternoon. Since the trough coming in is
moving through the overall ridge position its hard to get overly
excited with any significant amounts of precipitation.
However...this said it appears that there is a sub tropical
connection of moisture so have gone a little higher with the probability of precipitation
then ordinarily with the overall weak dynamics. The best dynamics
according to the GFS will come Wednesday as the 500 mb trough
finally moves across the County Warning Area. The ec has barely a ripple in the flow
at this time so kept forecast of probability of precipitation in chance category in most
areas. Gradual drying Thursday as a weak ridge redevelops.
Aviation...at the slc terminal...operational weather concerns are
minimal. Southeast winds will prevail through the taf period with
some gusty winds this afternoon and evening. However...there is a 30
percent chance that winds will be stronger than forecast for
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