911
FXUS65 KSLC 042257
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
357 PM MST Thu Dec 4 2025

.SYNOPSIS...A significant winter storm will impact northern and
central Utah late Thursday into Sunday morning. The potential for
unsettled weather continues through the middle of next week.

&&

.DISCUSSION...A significant winter storm will impact northern
Utah, central Utah, and southwest Wyoming from Friday through
Sunday.

Key Messages and Impacts:

- Mountain snow is expected across the northern and central Utah
  mountains from Thursday evening through Sunday morning, with the
  heaviest period of snowfall expected Friday night into Saturday
  morning. Storm total snow accumulations are expected to range
  from 1 to 3 feet of heavy, wet snow.

- Valley snow will be dependent on elevation and cold pool
  strength. Accumulations will most likely range from 1-2 inches
  in the Cache Valley and eastern Box Elder County, 3-8 inches in
  the Ogden Valley, 7-16 inches in Park City area, trace to 1 inch
  in the Salt Lake Valley, 1-3 inches near Ogden, and 1-3 inches
  in the Heber Valley. There is still a 25% chance that snow
  totals exceed these amounts.

- Snowfall will linger in the mountainous terrain of northern Utah
  through late Sunday morning before tapering off into early next
  week. Another system may graze Utah and southwest Wyoming early
  to mid-week next week, bringing another round of mountain snow.


Satellite imagery this afternoon is already showing a broad veil
of cloud cover pushing into northern Utah and southwest Wyoming as
moisture begins spreading over the area. This moisture is tied to
an incoming inland-penetrating atmospheric river that will bring
significant impacts across the northern half of the CWA from late
this evening through Sunday morning. While there still exists some
uncertainty with precipitation type in lower elevation valley
areas of northern Utah, accumulating snowfall is expected early
Friday morning before a transition to rainfall arrives as warmer
air spreads over the region.

Precipitation (already noted on northern Utah radar) will
gradually fill into the northern Utah mountains late this evening
and through the overnight period, eventually falling into valley
areas early Friday morning. Before any cold pools erode, light
snowfall is anticipated for valley areas from the Utah/Idaho
border southward through the Wasatch Front. As the overhead
airmass warms gradually through Friday morning, snow levels for
the lower elevation (and less sheltered) valleys are expected to
rise above valley floors, allowing for a transition to rain.
Before the transition to rain, snow totals are likely (75% chance)
to amount to less than 1 inch in the Salt Lake Valley and Utah
Valley, and upwards of 1 to 2 inches in the Ogden area.

For the more sheltered lower elevation valleys (i.e. Cache Valley,
eastern Box Elder Co., and Ogden Valley) the snow forecast becomes
more complex and a bit more uncertain as the strength of the cold
pools will ultimately dictate how much snow is seen in these
areas. At the very least, the thought is that valley cold pools
will be maintained for longer than the Wasatch Front, allowing for
a longer period of snowfall... and thus greater snow accumulation
potential. For the Cache, current model guidance supports anywhere
from 1 to 3 inches of snow at the valley floor, with upwards of 4
to 6 inches for the higher elevation portions of the valley by
mid-morning Friday. Similar amounts can be anticipated for eastern
Box Elder Co., with guidance in the Ogden Valley supporting
anywhere from 5 to 10 inches (high end amounts favored if the cold
pool holds strong).

By at least Friday afternoon snow levels are likely to rise above
most valley areas (outside of the Park City area), forcing rain on
top of the resulting snowpack. By Friday evening, upper level
support for heavier precipitation finally begins to spread across
the region, marking the beginning of the heaviest mountain
snowfall and valley rain. This period favoring heavy snow is
largely expected between 9PM Friday and 9AM Saturday, translating
from north to south through the overnight period. Behind the
heaviest precipitation, colder air will fill in the wake, allowing
for snow levels to drop once again. That said, there is unlikely
to be sufficient moisture and forcing in place to see appreciable
snowfall in lower elevation valleys in the wake of the heaviest
precipitation period... but a few snow showers may still be seen
on Saturday morning.

Upslope snowfall lingers across northern and central Utah through
Saturday, gradually tapering off through the overnight hours into
Sunday. When all is said and done, snowfall amounts in the
mountainous terrain across northern and central Utah will range
from 1 to 3 feet, with the higher end of the forecast falling
in the northern Bear River Mountains and the central Wasatch.

Conditions stabilize temporarily on Sunday in the wake of the
atmospheric river, however, we`ll find ourselves on the eastern
periphery of an upstream ridge with active weather continuing in
the PacNW region. As such, there is still a chance (15-25%) that
the northern Utah mountains do not stop seeing light snow showers
until after our next potential storm system slated for Tuesday/
Wednesday. Given the current guidance and the strength of the
aforementioned ridge, it seems unlikely that this Tuesday/
Wednesday system will bring another round of significant mountain
snow. More to come on this system in the coming days.

&&

.AVIATION...KSLC...Light NW winds will shift southerly by 01Z this
evening and most likely (70% chance) remain southerly through the
forecast period. Increasing moisture will yield gradually lowering
CIGs through the evening, falling to around 6kft around 01Z, and
falling to between 2kft-3kft around 10Z as snow showers approach.
Occasional snow showers then continue through the morning Friday
before gradually mixing with and changing to rain during the
afternoon. Heaviest precipitation expected Friday evening, when
probabilities for IFR approach 20%; LIFR probs 10%.

.REST OF UTAH AND SOUTHWEST WYOMING...Moisture will increase from
the NW this evening, with snow developing across northern Utah
valleys from late this evening through the overnight hours, with
periods of snow continuing through the morning before mixing with or
changing to rain Friday afternoon. Exception will be across SW
Wyoming where all snow (>90% chance for all snow) is expected. Two
scenarios emerge for Cache Valley and Wasatch Back, as probabilities
for rain vs. snow are nearly equal by Friday evening. Better than a
50% chance exists for valley terminals to see MVFR flight categories
develop between 04Z-08Z overnight, with ~25% chance for IFR.
Mountain obscuration will develop across the northern and central
mountains.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory from 11 PM this evening to 11 AM MST
     Friday for UTZ103-107.

     Winter Storm Warning from 11 PM this evening to 5 AM MST Sunday
     for UTZ108-112-113-117.

     Winter Weather Advisory from 5 PM Friday to 5 PM MST Saturday
     for UTZ109.

     Winter Storm Warning from 8 PM this evening to 5 AM MST Sunday
     for UTZ110-111.

WY...Winter Weather Advisory from 5 PM Friday to 5 PM MST Saturday
     for WYZ021.

&&

$$

PUBLIC...Webber
AVIATION...DeSmet

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