Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
318 PM MDT Sat Sep 24 2016
Synopsis...building high pressure will bring a drier and more
stable airmass through this weekend and the first part of next
week. A storm system is expected to bring moisture back to the
forecast area by midweek.
Short term (through 06z wednesday)...precipitation has all but
ended over the forecast area this afternoon as the Pacific northwest
storm system shifts east of the area. Clouds are lingering over the
northeastern quarter of the forecast area on the back end of the
trough with clearing skies over southern and western Utah. With less
in the way of overall cloud cover, temperatures have warmed a bit
from yesterday but maxes are still running 10-15f below seasonal
High pressure is moving in rapidly behind the exiting storm system
and will build over the forecast area through Monday. This will
result in dry and stable conditions with a steady warming trend.
Northeasterly flow over the area tonight will result in some gap
winds in the prone areas of Washington County, but these should
remain below advisory criteria. Otherwise, winds are expected to be
generally light through the early part of the upcoming week.
The Pacific northwest storm system is progged to split tonight as it
continues eastward. The northern part of the trough will move out of
the area but the southern part is expected to close off over
northern Mexico tomorrow near the Arizona border before tracking
back westward Monday. Ec/GFS indicate the system will then start to
lift back northward on Tuesday, which will start to bring moisture
back into southern Utah.
Long term (after 06z wednesday)...the closed low over Arizona is
forecast to push into southern Utah Tuesday night, and then
through the rest of the forecast area Wednesday and Wednesday
night. Have increased pops and sky cover a bit through this
period, as models are in decent agreement about both the timing
of this system and the fact that the low brings decent moisture
back into the area.
This moisture looks to linger through Thursday and Friday after
the wave exits to the northeast, which could allow for continued
diurnal showers and thunderstorms. Otherwise, southwesterly flow
is expected to slowly increase through the end of the week, as a
Pacific trough pushes into the West Coast.
The first piece of this trough is currently expected to push
across the area Friday night and Saturday, bringing an increased
chance of precipitation to primarily the northern half of the County Warning Area.
Looking ahead to next weekend, there is a chance that the larger
trough could bring cooler and wetter weather back to Utah, though
the best moisture and instability looks to remain north of the
area at the moment.
Aviation...clouds at the slc terminal will continue to gradually
clear through the evening hours with any lingering ceilings near 6kft
scattering out by 23z. Otherwise, northwest winds are expected
to transition to southeast by 04z.
Fire weather...the Pacific northwest storm system that has been
impacting the district over the last few days is exiting to the east
this afternoon. In its wake, high pressure is moving in rapidly
behind it. This ridge will remain in place through Monday, resulting
in dry and stable conditions with light winds. It will also usher in
a steady warming trend. A low pressure system over Arizona is
expected to track across Utah midweek, increasing moisture and
instability and bringing a return of showers and thunderstorms.
Short term/fire weather...traphagan
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