Winter Weather in Utah, January 9 to 10, 2024

Area Forecast Discussion
National Weather Service Salt Lake City UT
338 PM MST Tue Jan 9 2024

.SYNOPSIS...A series of storm systems will bring significant snow
to northern and central Utah through Thursday, with accumulating
snow possible to the lower valleys of southern Utah by Thursday
morning. Active weather remains in the forecast through the
latter half of the week and through the weekend, with the
potential of atmospheric river moisture impacting the area.

&&

.SHORT TERM (Through 00Z Friday)...The first storm system and
associated cold front of the series is approaching the Utah/Idaho
border this afternoon. Snow has been heavy along the boundary,
with strong and gusty winds also observed over portions of
southern Idaho. This boundary will slide southeast across northern
Utah through the early to mid evening, bringing a brief period of
heavy snow to locations as it passes. Combined with the strong
winds, this brings the potential for snow squalls, which could
significantly impact travel. Overall, compared to guidance
yesterday timing has slowed down by a couple of hours but have
made limited changes regarding snow totals and impacts. This will
still have very noticeable impacts for the evening commute. The
band looks to weaken as it moves into Utah county, with the
potential for snow decreasing for points south. Light snow will
continue overnight into Wednesday morning, at least for the higher
terrain, with a relative lull elsewhere.

The second system, which looks like a stronger version of the
first system, looks to make its way into northwest Utah during the
early afternoon. This front is expected to move across northern
Utah with similar timing to the front today, an hour or two faster
time of day wise. Given that it is stronger and more organized the
impacts will be more significant, valley snow totals will be
higher, and the likelihood of snow squalls is even higher. Would
encourage commuters to begin travel early or be prepared to delay
travel as needed with the timing of the front. Overall, have
brought northern Utah valley totals down just slightly if
anything, so did not see a need to upgrade any valley advisories
to warnings with the second feature, though Snow Squall Warnings
will be more likely. Guidance indicates that higher elevation snow
will drop off more sharply with the passage of this feature
compared to tonight, so overall snow totals will be similar for
the northern mountains with both features. Unlike the first cold
front, this second front is expected to hold together all the way
across southern Utah, bringing the potential for some accumulating
snow even to the lower valleys of southern Utah, including St.
George and the Lake Powell area. However, the front will have
weakened by the time it reaches those areas, so accumulations are
expected to be a half inch or less.

The arrival of these two systems will also bring much colder
temperatures to the area, and the combination of cold and wind
could bring apparent temperatures down low enough to result in
some issues for the national parks of southern Utah as well as
portions of the Wasatch Front. Will have to monitor for the
potential for headlines.

.LONG TERM (After 00Z Friday)...Our continuous moisture train will
persist Friday headed into the weekend and will only be bolstered
Saturday/Sunday by a passing area of low pressure within this
northwest flow. An incredible amount of snowfall awaits upslope
regions of the Wasatch Mountains, the Bear River Range and western
Uintas. Snow totals over a 3 day period (Friday through Sunday) are
forecast between 5 and 8 feet. Yes, feet. This is so much snow that
some of the color scales aren't able to compute it in certain
forecast models. This really will be a remarkable snow event for the
mountains. So, what is causing this? This event is being bolstered
by an atmospheric river. This means the amount of moisture available
for this system is much more than we've seen in recent events. There
are differences though in the amount of moisture forecast. Looking
at peak moisture from the GFS, statewide deep layer IVT values on
the order of 200 to 400 kg/ms are anticipated Saturday then
decreasing by Sunday. Comparatively, moisture values from the
ECMWF model are much less, only upwards of 100 kg/ms, during this
same time frame, instead favoring areas further west and south of
Utah. The amount of QPF associated with this event is thusly quite
high as well. Forecast SWE amounts in the mountains are noted
between 3 and 6 inches. Of course, amounts will become more honed
in in the coming days.

Now lets talk about the impacts to the northern and central Utah
valleys and to southwest Wyoming. Strong winds on Friday will lead
to blowing snow concerns Friday for southwest Wyoming. Snow showers
remain likely in the forecast from approximately Nephi northwards.
While not a guarantee, forecasts are currently indicating snow
levels are forecast to rise enough Saturday to allow for a rain and
snow mix along the Wasatch Front, into the west desert and into the
central Utah valleys in the afternoon. This would be short lived and
would shift right back over the snow by the evening. Snow showers
will begin to fill into the southern and eastern Utah by Saturday
afternoon as well with very minimal to no impacts expected.

Generally speaking, conditions will begin to dry out by Monday of
next week though we will remain under a northwest flow.

&&

.AVIATION...KSLC...Active winter pattern persists. Cold frontal
passage expected to bring a brief window (likely less than 2 hrs) of
snow squall conditions, including switch to gusty NW winds, IFR
CIGS, and VIS less than 1SM. Lingering scattered snow showers taper
off by early Wednesday morning, with winds expected to shift back S.
A similar weather progression is anticipated through Wednesday with
light snow developing by early afternoon, and another cold frontal
passage bringing potential snow squall conditions by late afternoon
to early evening.

.REST OF UTAH AND SOUTHWEST WYOMING...For northern terminals, an
active winter pattern persists. A cold frontal passage Tuesday
evening is expected to bring a period of gusty NW winds as well as
potential snow squall conditions (VIS less than 1SM, CIGS to IFR or
so) for a period of generally less than 2 hours. Scattered snow
showers persist thereafter, with some lessening coverage through
early Wednesday morning. By late Wednesday morning into the
afternoon, will once again see some light snow develop across the
region. Another cold frontal passage from north to south occurs late
afternoon into the evening hours Wednesday, bringing similar
conditions to that of Tuesday's frontal passage. For southern
terminals, fairly benign conditions are expected through much of the
TAF period, though will see the potential impacts from the second
cold frontal passage late Wednesday evening into the overnight hours
Thursday.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory until 5 AM MST Thursday for UTZ102>105-
     107-109.

     Winter Weather Advisory until 5 AM MST Thursday for UTZ106-
     116>118.

     Winter Storm Warning until 5 AM MST Thursday for UTZ108-110>113.

WY...Winter Storm Warning until 5 AM MST Thursday for WYZ021.

&&

SHORT TERM...Traphagan
LONG TERM...NDeSmet
AVIATION...Warthen

For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecity