Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 211135

Area Forecast Discussion
National Weather Service Salt Lake City UT
435 AM MST Wed Feb 21 2018

.SYNOPSIS...An active weather pattern will prevail through the
next 7 days as a series of weather systems move through the


.SHORT TERM (Through 00Z Sunday)...A longwave trough encompassing
the western CONUS will remain in place through the short term
period, as a series of shortwave features rotate through the mean
flow. The next wave to impact the region is digging through the
western Great Basin this morning, and will slowly translate
eastward across the forecast area today through tonight, weakening
as it does so. Weak moisture advection ahead of this wave today
followed by the passage of the trough axis tonight may squeeze out
a few mountain snow showers during this time, but otherwise have
little real impact on the forecast area.

A more potent wave currently digging southward along the British
Columbia coastline is forecast to dig into the Great Basin
Thursday, before slowly migrating eastward across the forecast
area Thursday night into Friday. The GFS has trended further north
with the track of this wave over the past 24 hours, however it
still appears central and southern Utah will see the brunt of
accumulating snowfall with this feature. This wave is expected to
quickly move east Friday night, as yet another shortwave trough
approaches the region. Large scale ascent ahead of this feature
will bring a chance of snow to the higher terrain of northern Utah
beginning Saturday, and have introduced PoPs accordingly.

.LONG TERM (After 00Z Sunday)...With the longwave trough
persisting over the western CONUS, a series of shortwave troughs
continue to pass through the Intermountain West through the
extended forecast. As one shortwave is exiting Saturday, another
drops in from the Pacific Northwest Saturday night into early
Sunday. Have increased POPs through this period, as at least a
quick shot of precipitation appears likely across the northern
half of the forecast area; this is especially true in the
mountains, with a (brief) period of moist unstable northwest flow
developing with the trough passage.

That said, this trough is progressive and fast moving, with the
trough axis already over Colorado by 00Z Monday. Good mixing with
this trough will make Saturday night/Sunday morning warmer than
the previous night, but don`t expect too much in the way of
temperature relief, as the trough also reinforces the cold airmass
(-17C at 700mb for much of the state by 18Z Sunday).

Sunday night into Monday largely looks to be a break in the
active weather, as the Sunday trough exits and the next trough in
the train digs into California. Details begin to break down a bit
Tuesday onward, but in general the pattern looks to remain cold
and active through the work week.


.AVIATION...Winds at the SLC terminal are expected to switch to
the northwest around 18-21Z, though there is a 30 percent chance
that winds remain southeasterly past 21Z. Ceilings may lower
through the day, but should remain above 7000 feet through at
least 00Z.





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