364
FXUS65 KSLC 210956
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
256 AM MST Fri Nov 21 2025

.SYNOPSIS...Dense fog has developed across several northern Utah
valleys and Uinta County, WY. This fog will dissipate by late
morning. Several disturbances will impact Utah Sunday through
Thursday, though there is little threat of heavy precipitation.

&&

.DISCUSSION...While the pattern remains largely active across the
West, Utah is likely to remain on the periphery of multiple storms
through at least Thanksgiving. Early morning upper air and
satellite analysis indicates an upper level low is shifting south
along the California coast. The northern stream remains active
through the eastern Pacific and into southern Canada.

As was the case Thursday morning, dense fog has developed across
the Cache Valley and eastern Box Elder County. Dense fog has also
developed across Uinta County, WY. Dense fog advisories are in
effect for these locations, with visibilities less than 1/4 mile
impacting the I-15 corridor from Brigham City to the Utah/Idaho
stateline, routes in the Cache Valley and I-80 from near Echo
Reservoir to Lyman, WY. Dense fog is developing along the Western
Davis Corridor as well. Will keep an eye on dense fog development
near the Great Salt Lake in Weber, Davis, and Salt Lake County and
will expand dense fog advisories if needed. Regardless, commuters
across these areas should be prepared for rapid decrease in
visibilities through about 10 AM.

The previously mentioned upper level low will eject east and then
north across the 4-Corners area. Ensemble consensus is the
precipitation shield from this low will bring light precipitation
to portions of south central and southeastern Utah Sunday, with
the mean range from around 0.05-0.10", heaviest across eastern
Kane County.

In the wake of this upper level low, a northern stream shortwave
trough will dig into the northern Intermountain Region Monday into
Tuesday. The majority of ensemble members now favor this trough
to continue to dig into the central Rockies, bringing light
precipitation to the northern mountains Monday afternoon into
Tuesday morning. And by light, the cluster ensemble mean is 0.03"
for the Bear River Range. The dusting of snow aside, this will
usher in a colder airmass behind the cold front. Expect
temperatures to fall around 5 to 10 degrees between Monday`s highs
and Tuesday`s highs, especially across northern and central Utah.
By Tuesday, the Wasatch Front will be struggling to reach the low
40s.

For lower Washington County and the Virgin River area between
Springdale and St. George, this shift toward a colder solution has
brought the threat of freezing temperatures both Tuesday and
Wednesday mornings, especially outside of the St. George City
area. the highest chance for a freeze will be Wednesday morning
(around 30-40% chance, except in the St. George area where it is
closer to a 10% chance due to northerly gap winds in the wake of
the cold front). This would be the first freeze of the fall for
these locations, so those with frost/freeze sensitive plants
should continue to monitor the forecast and potential Freeze
Watches and/or Warnings.

As just mentioned, there is the moderate potential for gusty gap
winds Monday night into Tuesday morning and again Tuesday night
into Wednesday morning behind the cold front across lower
Washington County. These northerly winds would mainly impact areas
near Black Ridge Canyon including Toquerville, Hurricane, and La
Verkin. Right now, expectation is gusts will peak around 40-45
mph.

Looking ahead to Thanksgiving, a portion of the ensemble members
continue to suggest northwest flow coincident with jet max will
set up across northern Utah, bringing a period of precipitation.
Around 50% of members would bring around 0.05-0.10" of
precipitation to the northern mountains, lighter in the valleys,
with some potential for at least a period of light snow for
benches from SLC north. 25% of the ensemble members are
significantly more pessimistic, with precipitation remaining well
north of the Utah. And then there`s the final 25% or so that
suggest a deeper, colder system with up to 0.25" for the
mountains, up to 0.10" for the valleys, with potential at least
bench snow all the way to central Utah. This is something to
continue to monitor if you have Thanksgiving travel, but given the
models are in three main clusters, a weak system that brings very
light precipitation, a dry period with precipitation remaining
well north of the area and a much deeper, colder
system...confidence in any particular outcome is low.

&&

.AVIATION...KSLC...Mainly VFR conditions will persist for the
KSLC terminal through the period. ~30% chance of FG through 16Z
could briefly reduce VIS to MVFR/IFR, otherwise dry conditions
with a few high clouds will continue through the day. Winds will
be light and diurnally driven.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions exist across
most of the airspace with some intermittent IFR/LIFR across
northern valleys due to FG. This will burn off by mid morning.
Otherwise, a few high clouds and dry conditions will continue
along with light and diurnally driven winds.

&&

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Dense Fog Advisory until 10 AM MST this morning for UTZ103-107.

WY...Dense Fog Advisory until 10 AM MST this morning for WYZ021.

&&

$$

Kruse/Mahan

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