Scientific Forecaster Discussion
fxus65 kslc 181538
Area forecast discussion
National Weather Service Salt Lake City Utah
938 am MDT Wed Oct 18 2017
Synopsis...a warm airmass will remain in place through Thursday. A
weak disturbance will lift across Utah late tonight into tomorrow,
followed by a stronger and colder storm system for Friday
afternoon into Saturday.
Discussion...the forecast area is under a zonal flow this morning
with a warm airmass aloft, 700mb temps in the +6c to +8c range.
Some clouds have moved into southwest Utah ahead of a weak
disturbance currently stretched across Southern California and
southern Nevada. The influence of these clouds will drop maxes by
a couple of degrees there while high temperatures remain similar
to what was observed yesterday across much of the rest of Utah and
southwest Wyoming. Overall, temperatures will be quite mild over
the higher terrain and near to slightly above seasonal normals at
The disturbance is progged to move into southern Utah
tonight/tomorrow morning and then track northeast across Utah
during the day Thursday. Moisture will be quite limited, but
instability from the wave could be enough for a few showers over
the higher terrain. The flow aloft will also become more southerly
as a larger storm system approaches the Pacific northwest coast.
This will improve mixing and allow for a few degrees of warming in
valley locations, resulting in maxes up to 10f above seasonal
Winds will become breezy for many locations across the forecast
area by Friday as the larger storm system approaches. This system
is still on track to move through Friday afternoon into Saturday,
bringing colder air to all but far southeast Utah as it moves
through. Maxes Saturday are expected to be up to 20f cooler than
values expected Thursday, which would be about 10f below climo.
Moisture, as has been the case with a lot of systems impacting the
area lately, looks to be limited with this passing trough, so
associated precip totals should not be impressive. 700 mb temps in
the -5c to -7c range would keep any snow above northern Utah
valley floors. High pressure is expected to return once again for
early next week, resulting in dry conditions and another warming
No updates expected to the forecast this morning.
Aviation...the dry/stable air mass across northern Utah will
maintain VFR conditions under mostly clear skies today. A weak
weather disturbance over southern Utah tonight will spread mid and
high level clouds across the terminal. VFR conditions will persist
overnight and into Friday. Light northwest winds will develop
between 17-18z, then turn back to the southeast around 04z this
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