FXUS65 KSLC 111035

Area Forecast Discussion
National Weather Service Salt Lake City UT
335 AM MST Mon Dec 11 2023

.SYNOPSIS...A couple of moisture starved weather systems will
cross the region early in the week. A cut-off low pressure system
will become established across Arizona for the middle to latter
portion of the week, resulting dry and cool conditions across Utah
and southwest Wyoming.


.SHORT TERM (Through 12Z/5AM Wednesday)...A predominantly zonal
flow resides across much of the Interior West early this morning.
A weak embedded shortwave is noted crossing the northern Great
Basin, while further upstream a somewhat better defined shortwave
is noted digging along the British Columbia coastline. Meanwhile, a
narrow band of moisture extends across southern Idaho and far
northern Utah, resulting in occasional light snow across the
Cache Valley/Bear Lake area and adjacent terrain.

The former wave will minor out this morning as it continues east,
in response to modest mid level ridging ahead of the upstream
wave. The band of moisture will continue to linger near the Idaho
border bringing a chance of snow, while dry and warmer air aloft
resides across the remainder of the forecast area. This warming
will be most notable across the higher terrain as well as much of
southwest Utah where valley temperatures will reach the 50s. Given
the low sun angle and limited flow, warming across northern and
eastern valleys is much less certain, as cold pools remained
across typical areas such as the Salt Flats, Uinta Basin, and
Castle Country. The 00Z KSLC sounding also indicated a fairly
substantial inversion layer in the 800-750mb layer, which should
remain in place today. As such could begin to see an increase in
urban haze today assuming this shallow cold air remains in place.

The upstream, moisture starved wave is forecast to move inland
across the Pacific Northwest today, then slowly dig into the
Great Basin tonight before evolving into a closed low across
Nevada Tuesday through Tuesday night on its way to the Desert
Southwest. Given the lack of moisture any chance for precipitation
is minimal. Temperatures aloft will cool, however again with
limited sun angle and very weak flow any valley inversions may be
tough to mix out through Tuesday.

Tuesday night, as this low makes its way toward Arizona, there is
some potential for locally enhanced canyon winds along the
Wasatch Front/Cache Valley within a region of fairly modest
easterly flow aloft. This will need to be monitored, as although a
stronger downslope event looks unlikely, certainly could see
advisory level wind gusts near typically prone areas of the
northern Wasatch Front and Cache Valley owing to modest low level
cold advection and a somewhat favorable pressure gradient.

.LONG TERM (After 12Z/5AM Wednesday)...A cut-off low centered over
Arizona looks to largely play little part in the weather forecast
across Utah mid-week, aside from some colder temperatures it'll pull
down Thursday morning. The Bear River Valley will be particularly
chilly with lows forecast into the single digits. The cooldown will
be fairly short lived as high pressure is forecast to build in for
the remainder of the week; ushering in warmer air from the
southwest. This ridge of high pressure is forecast to be in place
through the weekend and allow for continued mild weather conditions
and seasonal to slightly above seasonal temperatures across the


.AVIATION...KSLC...Lights winds are expected to persist throughout
the forecast period. Lowered CIG between 050 and 070 are expected
until 18z with improvement thereafter.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected
throughout the forecast period across much of Utah. LGU is forecast
to see a period of MVFR CIG today with snow showers nearby along
with Southwest Wyoming (also forecast under MVFR CIG) through the
early afternoon hours. Additionally, several forecast models are
calling for ~25% chance for freezing rain at EVW this evening. At
this time, confidence is not high enough to include in the 12z TAF





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