Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 042310

Area Forecast Discussion
National Weather Service Salt Lake City UT
410 PM MST Sun Dec 4 2016

.SYNOPSIS...A cold front will enter northern Utah late tonight,
then sweep south into central Utah during the day Monday. The much
colder temperatures behind the front will turn even colder as a
second colder storm system will bring snow and the coldest
temperatures of the season to most of Utah and southwest wyoming
for midweek.


.SHORT TERM (Through 00Z Thursday)...The strong west-northwest
flow aloft just to the north of Utah late this afternoon will sag
south into northern Utah tonight. Weak shortwaves embedded in the
flow will race east across northern Utah tonight through Monday
morning, and will push a cold front south into central Utah by
Monday afternoon.

Snow will develop along the cold front across far northern Utah
late this evening, then follow the front south across northern
Utah later tonight through Monday morning. The front and the
supporting low-level cold advection will remain fairly strong as
it settles in central Utah during the afternoon. Though the front
remains strong, snow will likely taper off as the mid-level
dynamic and thermal support shears off to the east and disconnects
from the low level feature.

A second bitterly cold trough currently over the northern Gulf of
Alaska will track south along the BritCol coast Monday, then head
southeast through the Pacific Northwest and eventually move
through the Great Basin on Tuesday. This second feature will
interact with the now stalled baroclinic zone over central Utah.
Good convergence into the low-level baroclinic zone combined with
strong dynamic and thermally driven lift from this second trough
will end up generating widespread snow along and to the north oft
baroclinic zone Tuesday through Tuesday evening.

A increasingly cold and stable northwest flow behind the exiting
trough late Tuesday night/Wednesday will bring an end to snow by
early Wednesday. Afternoon temperatures Wednesday, even with skies
beginning to clear, will be closer to normal lows than highs for
the date.

.LONG TERM (After 00Z Thursday)...The global models are in fairly
good agreement that a ridge will temporarily build over the CWA
after 00Z Thursday which will set up a mainly clear night and
coldest temps of the week. The models tend to drift apart after
about 00Z Friday with the GFS a little more flatter with the wave
coming in across northern portions of the intermountain region. The
atmospheric river is tapped with this near zonal flow and makes good
headway into the intermountain region. Have increased the PoPs
across northern portions for Thursday night and Friday.

With a lot of clouds/moisture across the region have increased the
temps some as the inversion should be erased by Friday, especially
at night. Have leaned towards CONSMOS/MOS guidance.

My concern after this time period is that there is a lot of energy
running through this zonal flow and believe there will be more
buckling of the flow as the models probably not resolving this in
the extended. Therefore leaned towards climo for Saturday and Sunday
as not confident in the model`s solutions in this type of pattern.


.AVIATION...VFR conditions and southerly winds will prevail at the
KSLC terminal through late tonight before winds turn northwest
behind a cold front which is expected to arrive within in the 08-11z
timeframe. CIGS will fall to 6kft or lower after 04-06z...then MVFR
to IFR conditions in snow will develop behind the cold front. Snow
is expected to be brief and mostly taper off by mid-morning Monday
with conditions improving to VFR.





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