Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 212124

Area Forecast Discussion
National Weather Service Salt Lake City UT
324 PM MDT Mon Oct 21 2019

.SYNOPSIS...Behind the exiting Pacific Northwest storm system, high
pressure will build through midweek. The next weak storm system
will impact Utah and southwest Wyoming Wednesday into Thursday.
High pressure will return Friday before a stronger storm system
approaches for the weekend.


.SHORT TERM (Through 00Z Friday)...Pacific Northwest storm system
has all but exited the forecast area this afternoon. Earlier
showers over the mountains of northern Utah have all but
dissipated, though some clouds still linger. These will thin out
through the evening. Maxes today are running 5F or more below
seasonal normals but are an improvement from yesterday behind the
front. High pressure centered off the California coast will build
back over the area tonight into tomorrow, allowing maxes to
return to values near to just below climo for tomorrow afternoon.

A small amount of precipitation is possible over northern Utah and
southwest Wyoming Tuesday afternoon into the early evening as a
weak shortwave crosses the area. A more noticeable system is
expected to follow for Wednesday afternoon into early Thursday as
a back door front moves over the front of the California ridge.
Best dynamics and moisture will be well east of the area, but some
precip is possible, primarily for northeastern portions of the
forecast area. The more noticeable impact will be on temperatures,
with maxes going back down to values 5-10F below seasonal normals
by Thursday afternoon.

.LONG TERM (After 00Z Friday)...Longwave upper ridge off the
West Coast into the Gulf of Alaska will persist through the period.

The next shortwave trough to impact the forecast area will be
topping the ridge to our northwest Friday and Saturday. That will
keep Utah in dry west to northwest flow both days in advance of this
system. Expect temperatures to be rising back to near normal
values by Saturday.

By Sunday the shortwave will dive into the Great Basin, turning the
flow cyclonic and allowing a cold front to push across the state.
The ensembles and deterministic models all agree on some trough
configuration and the arrival of a front, yet the details are
significantly different. What is more certain is a cooldown for
Sunday and Monday with increasing chances of rain and snow,
especially across the north. The current forecast calls for about a
15 degree drop across the north from Saturday to Sunday with about a
5-10 degree fall in the south.


.AVIATION...Gusty northwest winds at the SLC terminal should
diminish in intensity between 23-00z, with the switch to southeast
diurnal winds inching in between 03-04z. There is a 30 percent
chance that winds will remain light north or variable until about
06z. VFR conditions will prevail through the valid TAF period.


.FIRE WEATHER...The district can expect increasingly dry and mild
conditions through midweek under the influence of high pressure.
A weak storm system will bring a cold front through Wednesday into
Thursday, with some associated light precipitation possible over
portions of northern Utah, primarily over the higher terrain. High
pressure will return for Friday before a potentially stronger
storm system impacts the area late Saturday into Sunday.




LONG TERM...Billingsley

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