Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
908 PM MDT Tuesday Sep 30 2014
Synopsis...a cool Pacific storm will move through the area
tonight through Wednesday. High pressure will build over the area
Thursday through at least early next week.
Discussion...a long wave trough remains over the western US this
evening with a cool short wave dropping into it. This wave is over eastern
or/western Idaho at this time and will cross northern Utah overnight through about
midday Wednesday before moving off to the east.
The associated cold front has crossed about the northern 1/3 of the
state and is accompanied by a disorganized band of scattered
showers. These have shifted out of the far northern County Warning Area and will
continue to shift south overnight as the front advances through the
County Warning Area.
The airmass with this trough is on the cool side with temperatures falling
to -4c at 700 mb across most of northern Utah with a few pockets as low
as -5c by 18z Wednesday. However...this colder air is well upstream of
the band of showers and snow levels will remain fairly high with
these as they progress southward. So dont expect any impact for any of
the mountain passes overnight.
There could be instability showers in the cold pool over northern Utah
tomorrow with snow levels down to 6500 feet or so but these would
be scattered and brief and once again expect little if any impact
A fairly tight northwesterly pressure gradient sets up across the County Warning Area by
middle morning tomorrow and tightens across the south and east through
the afternoon into tomorrow night. This should generate gusty northwesterly
winds in the normally favored downslope areas of southern and eastern Utah
but upper support is not that strong through the afternoon so do not
expect winds to get too strong. The upper support gets stronger
across southwestern Utah after 00z Thursday and the surface gradient stays tight
through the evening so speeds could reach advisory levels below canyons
and gaps in Washington Colorado. Winds should drop off in all areas by
An upper ridge is forecast to strengthen over the West Coast
states Thursday through the weekend bringing dry conditions and a warming
trend to the County Warning Area.
Updated earlier to trim probability of precipitation back across the far north for the
night and adjusted the southward timing of the showers as well.
Tweaked winds and sky a bit for tonight too. No additional updates
Aviation...winds at the slc terminal will be mostly northerly
through the night. Passing showers could bring variable winds at
times through about 08z. Winds could become light and variable at
times again between about 11-14z. VFR conditions will prevail.
Ceilings near 7000 feet are possible through about 08z if a shower crosses
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