Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 140420

Area Forecast Discussion
National Weather Service Salt Lake City UT
920 PM MST Tue Feb 13 2018

.SYNOPSIS...The upper level low pressure system off the California
coast turn back to the east and weaken as it moves through Arizona
and southern Utah Wednesday night. The next trough will move into
Utah from the Pacific Northwest on Thursday.


.DISCUSSION...The upper low now established off the southern and
central California coast will produce downstream height rises
across the Great Basin tonight through early Wednesday. Scattered
low topped convection across the southern half of Utah this
afternoon has weakened this evening. Anticipating some light
showers to persist overnight, though with only weak thermally-
driven lift and a rather dry mid-level air mass do not expected
any significant precip to develop through Wednesday morning.

The next upper level trough digging southeast out of the Gulf of
Alaska will reach the Pacific Northwest Wednesday morning. This
feature will initially serve to pick up the weakening coastal
California low and drag it east through Arizona/southern Utah as
an open wave Wednesday night. This wave, though weakening, will
tap into the moisture plume over southern Arizona. Most of this
entrained moisture will remain south and east of Utah, though what
does slip into southern Utah will help bring a but more
substantial precip to the south for Wednesday afternoon/evening.

The advancing Pacific Northwest trough will energized precip
across mainly the western half of the state late Wednesday
night/Thursday. The heaviest precip with this trough will likely
concentrate across far northern Utah close to the best dynamics
and mid-level cold air, and along the strengthening low-level
baroclinic zone over central/southern Utah Thursday.

Dynamic subsidence in the wake of this trough will dissipate much
of the precip Thursday night, though the moist cyclonic northwest
flow behind this feature should keep clouds and maybe some light
snow over the northern mountains overnight and into early Friday.


.AVIATION...Light and variable winds at the SLC terminal will shift
to southeasterly after about 04z and persist overnight into Wed
morning. Winds could become gusty after about 16-17z. Clouds will
increase after about 06-08z but any cigs will remain abv 7000 ft.





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