Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 302252

Area Forecast Discussion
National Weather Service Salt Lake City UT
352 PM MST Wed Nov 30 2016

.SYNOPSIS...The next storm system will spread into northern Utah
tonight and slowly cross the region Thursday through Friday
morning. A stronger and colder storm system will impact the
region early next week.


.SHORT TERM (through 12Z Saturday)...Diffluent flow aloft has kept
a stream of mid and high clouds across most of the county warning
area today, as a warm front moved in from the west.

The shortwave digging south tonight will drift into portions of
the northern county warning area after midnight, with the onset of
precip along the Northern Wasatch Front taking place closer to 3
am and central and southern Wasatch Front after 6 am. The airmass
will be cold enough to create travel impacts for the morning
commute with light snow accumulation on roadways since road
surfaces have cooled thanks to previous cold systems. With light
accumulation and sufficient mitigation of travel corridors during
the morning and daytime hours, didn`t feel any highlights were
necessary at this time. Another disturbance will move through the
county warning area Thursday night bring another threat of light
snow, mainly to the mountains.

As previously mentioned, the airmass will be quite cold with 700mb
temperatures dropping to near -13C by sunrise Thursday and
remaining cold through Friday night. Temperatures will run about
4-8 degrees below normal the next couple of days as a couple of
weak disturbances move through the region. The second disturbance
will dig southward forming a closed 700mb low over Arizona by
Friday afternoon. The surface gradient will strengthen over the
southern and western valleys Friday through early Saturday with
the strongest winds expected in the north-south oriented canyons
of Washington County. Have wind forecast just shy of advisory
levels at this point as winds aloft at 700mb not showing much
support as winds are less than 20 kts.

.LONG TERM (After 12Z Saturday)...The splitting trough is progged to
exit the forecast area Saturday morning to the east. However, cannot
rule out a few showers over the higher terrain of northern Utah
Saturday and Saturday night with some moisture lingering in a warm
advection pattern. This warm advection will also bring a gradual
warming trend in temperatures with maxes running up to 5F above
seasonal norms by Sunday afternoon.

The warming trend will be short lived, however, with the coldest air
of the season expected to move into the forecast area early next
week with the next approaching storm system. Global models push the
initial frontal boundary through Sunday night/Monday with the GFS
about six hours faster than the EC. All models show a decent burst
of precip with the front, though given the Arctic nature of the
airmass, it will not be quite as moist as previous systems. Precip
is then expected to continue through Tuesday in instability from the
cold pool. 700 mb temps are expected to drop as low as -18C to -20C
by Tuesday afternoon. EC/GFS both show the system finally tracking
out of the area Tuesday night/Wednesday morning, though a few
showers could linger over the higher terrain of northern Utah into
Wednesday afternoon. Models are in relatively good agreement and
have not changed much over the past few runs so have not made many
changes to the POP grids.  Maxes are expected to be up to 20F below
seasonal normals Wednesday afternoon. However, the airmass is
expected to warm quickly aloft with high pressure moving back in
after day seven.


.AVIATION...The SLC terminal will see VFR conditions through the
evening with cigs above 6000 feet. Cigs are expected to drop to or
below 6000 feet AGL after midnight, with occasional low-end MVFR to
high-end IFR conditions in snow beginning after about 11-12Z and
persisting through the morning. Southerly winds are expected
through the evening hours.




SHORT TERM...Struthwolf/Dewey
LONG TERM...Traphagan

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