Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 210449

Area Forecast Discussion
National Weather Service Salt Lake City UT
949 PM MST Tue Nov 20 2018

.SYNOPSIS...An upper level trough over the eastern Pacific will
advance east into Utah on Thursday. A second colder trough will
move into the region from the northwest for late Friday through
Saturday. High pressure aloft will return late in the weekend.


.DISCUSSION...High pressure aloft still centered across the
interior west this evening will shift east of Utah by late Wednesday.
Looking at one more day of dry and very stable conditions with
little change in lower valley temps and persistent urban haze.

Significant changes are still on tap for this upcoming holiday
weekend. The well-defined upper trough currently positioned along
135W will finally make it`s move to the west coast by Wednesday
evening. Model guidance does show some weakening of the trough
as it moves east into western Utah early Thursday. Though
weakening, this trough does maintain sufficient baroclinic
structure moving through Utah to support the current high Pops
in the forecast for the northern half of the state.

Looking at short break in widespread precip behind the exiting
trough Thursday evening. A fast-moving shortwave moving through
southern/central Idaho late Thursday night will generate
additional precip across the Wasatch range and adjacent valleys
into Friday morning.

The second upper trough digging southeast from the Gulf of Alaska
will bring significantly colder air into the area late Friday
night through Saturday. The structure of this second feature
appears to be setup for a substantial snow event across northern
and central Utah through Saturday afternoon. Strong low-level
frontogenic forcing developing near the Idaho border will persist
as the boundary progresses south into central/southwest Utah
Saturday morning. Solid dynamic lift from the mid-level trough,
increasing instability with the mid-level cold pool and a
favorably positioned exit region of the jet near the low-level
baroclinic zone all point toward moderate to heavy snowfall
potential. Will likely be issuing additional winter weather
highlights to address this second storm in subsequent forecast

High pressure aloft will rebound across the area Sunday through
at least the early portion of next week. The next series of
active storm system could return the western states late next


.AVIATION...High pressure across northern Utah will maintain VFR
conditions and light winds at the KSLC terminal through the
current TAF period.


UT...Winter Weather Advisory from 6 AM to 6 PM MST Thursday for




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