Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 061704

Area Forecast Discussion
National Weather Service Salt Lake City UT
1004 AM MST Wed Dec 6 2017

.SYNOPSIS...Strong high pressure centered to the west of Utah
will maintain a stable northerly flow across the Great Basin
through the end of the week.


.DISCUSSION...Observations from the 12z SLC Raob this morning
indicate a significant warming aloft at 700mb as the temperature
warmed nearly 5C over the last 24 hours. Also, comparing the last
few soundings, the inversion is inching lower and lower to the
ground under northerly flow aloft. With building heights under a
ridge of high pressure to the west, the big weather concern over
the next few days will be the developing inversion.

Satellite imagery shows the shortwave sliding south through the
northern Rockies this morning on the back side of the strong ridge
spilling over into Alberta, Canada. As the surface pressure
gradient tightens with this shortwave moving south, northerly
winds are expected to increase mainly across southwest Utah today
into this evening. This event looks to be marginal, so no
headlines will be issued at this time, however will keep an eye on
this area for further guidance.

Made some minor updates to the forecast this morning to account
for some valley fog in Tooele and Heber, but expecting this to
dissipate by late morning. The fog detected in the Bear River
valley has lifted as well as some other valleys. With the
increased northerly winds expected today this may aide in mixing
out some valleys for fog conditions tomorrow, however with clear
skies and cold air in place it may just help to lessen the effect.

.LONG TERM (AFTER 12Z SATURDAY)...(Issued 323 am MST)...
Persistence is the best bet through the long term, with potential
of expansion of lower valley stratus and fog threats across the
prone northern valleys. The mean upstream blocking pattern will
continue through the extended, and longer than that when a peruse
of global wave pattern projections takes place. Not much to say
past that.

Maintained going forecast trends of gradual warming in the mtns and
near stagnant temp conditions in the valleys (especially northern
ones) due to the widespread stable/dry airmass driving lower valley
inversion conditions each day.


.AVIATION...Light and variable winds at the SLC terminal as of
17Z are expected to increase from the northwest around 18-20Z.





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