174
FXUS65 KSLC 291058
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
358 AM MST Sat Nov 29 2025

.SYNOPSIS...A cool and stable airmass will reside across the
region today. An approaching early winter storm system will cross
the region late tonight through Sunday. Cooler and stable
conditions will follow for Monday, with another system expected
midweek.

&&

.SHORT TERM (Through 12Z Monday)...

Key Points:

- An early winter storm system will bring widespread accumulating
  snow to the higher terrain Sunday through Sunday evening.
  Northern Mountains will likely see 4-10" of new snow, with 2-7"
  across the central and southern mountains.

- Snow levels across northern Utah will fall near the valley
  floors Sunday, with accumulating snow in the 1-3" range expected
  along the benches of the Wasatch Front, as well as the Wasatch
  Back. Minor accumulation (T-1") is possible along the valley
  floors of the Wasatch Front should precipitaiton transition to
  snow.


The forecast area remains along the upstream periphery of a
longwave trough, which encompasses much of the CONUS early this
morning. This leaves the area susceptible to shortwave features
digging into the mean longwave position, and will make for a
relatively active pattern over the coming days. The initial wave
which passed well north and east of the area late Friday through
Friday night has left a trailing frontal boundary across southern
Utah early this morning. Cooler air in the wake of this boundary
will result in afternoon highs running roughly 10F lower this
afternoon and near climo across most valleys with the exception to
the lower deserts of southern Utah.

Looking upstream, the next shortwave trough is currently noted
along the British Columbia coastline digging southeast. This
feature will cross the Pacific Northwest later today through
tonight, before digging through the Great Basin Sunday. Although
there are some minor variations within the model solutions
regarding how this trough evolves, the overall consensus
consolidated around this trough evolving into a closed low across
the interior Pacific Northwest, before opening and crossing the
forecast area as a positively tilted open wave Sunday through
Sunday evening. As such confidence is increasing in the likelihood
of snowfall across much of northern, central and eventually
potentially southwest Utah during this timeframe.

Large scale ascent within a region of upper diffluence will
spread across far northern Utah as early as late tonight, then sag
south during the morning hours Sunday. This will allow for
widespread albeit light precipitation through Sunday morning. The
upper trough axis will swing through northern and west central
Utah late Sunday morning through Sunday afternoon representing the
window for heaviest precipitation across the Wasatch Front and
I-15 corridor into central Utah. In the wake of this axis,
precipitation will likely become increasingly orographically
forced later Sunday afternoon through Sunday evening before ending
Sunday night.

With the incoming airmass around -8C at 700mb, snow levels will
quickly fall near or just above most valley floors across northern
Utah Sunday morning. With the window for heaviest precipitation
coming during the afternoon and with somewhat marginal
temperatures, precip type along the valley floors may fluctuate
between rain and snow with any accumulation remaining confined to
grassy and elevated surfaces. Above 4500 feet the potential is
certainly there for accumulating snowfall along the benches as
well as the Wasatch Back, most likely in the 1-3" range across
these areas. The 25th-75th percentile for precipitation across
the northern mountains is roughly .25-.75" which would yield 4-10"
of snow accumulation by Sunday evening. A more favorable or less
favorable orographic window will determine which end of this range
is favored (or exceeded). With the airmass eventually falling
near
-9C Sunday evening like effect showers are possible downwind of
 the GSL into Salt Lake or eastern Tooele counties.

Further south, the mean low-mid level trough axis will swing
through central and southwest Utah Sunday afternoon and evening.
Model guidance is looking for favorable for a window of
precipitation as this axis passes, with the potential for
orographically driven precip lingering into the evening hours.
This area will remain a bit displaced from the core of the colder
air aloft, thus snow levels look to remain above 5000 feet through
much of the event. A somewhat shorter duration looks to keep snow
totals in the 2-6" range across the higher terrain, with minor
accumulation across higher valleys.

Large scale subsidence will bring an end to any lingering
precipitation Sunday night, with a cool and stable airmass
settling across the forecast area for Monday. Afternoon highs
Monday will struggle to reach the 40F mark across northern and
western valleys including KSLC.

.LONG TERM (After 12Z/6AM Monday)...Cold, northerly flow will
prevail Monday into Tuesday morning behind the exiting low. Some
of the coldest temperatures of the season are likely for much of
the region as a result, with lows in the upper teens for most
valleys outside the Wasatch Front. The first freeze may be
realized for Lower Washington County during this period, with a
20-30% chance for temperatures to reach freezing on Monday and
Tuesday morning.

Transient ridging is expected late Monday into Tuesday before a
shortwave trough deepens across the western US late Tuesday into
Wednesday. This system will originate from a longwave troughing
pattern across central Canada, which means we`ll be dealing with an
overall pretty moisture-starved system. Regardless, precipitation
chances increase late Tuesday as this system deepens across the
region, continuing into Wednesday morning before the shortwave
phases into an area of low pressure off the coast of southern
California. Ensembles still remain split in the evolution of this
shortwave. Around half of ensemble members take the wave on a more
westerly track through the Great Basin, with a shorter residence
time over Utah and southwest Wyoming. This solution would result in
overall light precipitation areawide. The other half favors the wave
deepening directly across the Intermountain Region, which would
result in a wetter scenario. Precipitation type for valley locations
is the other big forecast question that remains with this storm.
Ensembles currently depict a spread of H7 temperatures between -8 to
-10C accompanying this system, which translates to snow levels right
around valley level across the Wasatch Front. All this to say,
details are still quite uncertain with this mid-week storm. Will
continue to monitor as we get closer.

&&

.AVIATION...KSLC...Light, northerly flow continues this morning in
the wake of yesterday`s frontal passage. Southeasterly drainage
winds may briefly build in between 17-20z -- otherwise,
northwesterly winds prevail through this afternoon before
transitioning to the southeast after roughly 03z Sunday. VFR
conditions prevail through the period, though low clouds building in
across northern Utah will yield mountain obscuration early Sunday.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions prevail for all
regional terminals today. Generally light winds expected areawide,
with mainly north to northwesterly winds across the northern portion
of the airspace. Increasing low-to-mid level cloud cover is expected
to increase from the northwest gradually early Sunday.
&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

SHORT TERM...Seaman
LONG TERM...Whitlam
AVIATION...Whitlam

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