Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 032300

Area Forecast Discussion
National Weather Service Salt Lake City UT
400 PM MST Sat Dec 3 2016

.SYNOPSIS...A mild west northwest flow over Utah through the
balance of the weekend will give to a very cold air mass for the
first half of the upcoming week. The coldest temperatures of the
season are anticipated with snow for mainly the northern half of
the state.


.SHORT TERM (Through 00z Wednesday)...Shallow and moist low-level
warm advection has maintained cloud cover along the Idaho border
and south through urban corridor this afternoon. The shallow
nature of the lift generated by the thermal advection has limited
precip to very light showers across the far northern mountains.
Any real chance at even light precip should end early this evening
as moisture pushes off to the east into Wyoming.

Seasonal or slightly higher temperatures are expected on Sunday
ahead of what looks to be a very cold Pacific trough arriving
early in the upcoming week. This trough will be tapping into some
of the coldest air of the season as it moves east along the
southern Alaska coast, then southeast into Pacific Northwest,
northern Rockies and northern Great Basin early in the week.

The leading near 700mb baroclinic zone will push into northern
Utah late Sunday night, then settle into central Utah by Monday
evening. This low-level baroclinic zone initially will produce
light precip across the north as the mid-level thermal and dynamic
support for lift is not particularly strong and will remain near
and north of the Idaho border.

A second stronger/colder disturbance will dig southeast in the
Pacific Northwest Monday night, then carve out a broad upper
trough across much of the western CONUS for Tuesday. This second
feature will draw the near 700mb baroclinic zone over central back
north into northern Utah. This boundary will then interact with
the very cold mid-level air mass and dynamic lift associated with
the trough to generate widespread snow along the baroclinic zone
and north in the colder air during the day Tuesday.

.LONG TERM (After 00z Wednesday)...One of the coldest airmasses
of the year will be building into the area behind a cold front to
start the long term forecast period. Much of the model guidance
indicates at least light snow showers will be possible across much
of the state into Tuesday evening and possibly early Wednesday
morning. 700mb temperatures range from -18C to -20C depending on
the model in the wake of this front. Very cold temperatures are
expected across the state Wednesday and Thursday.

Ridging is expected to build in behind this front with fairly rapid
mid-level warm air advection through the Wednesday. Expect valley
inversions will keep valleys colder, even with warming 700mb

The polar jet streak coincident with a fairly strong shortwave will
move into the Interior West later Thursday bringing the threat for a
fairly widespread precipitation late Thursday into Friday
morning...continuing through Saturday. For now, started to increase
pops, especially across the north.


.AVIATION...VFR conditions and light southerly winds will prevail at
the KSLC terminal through the TAF period. There is a 30% chance of
CIGs below 7K feet dissipating by 01-02Z.





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