Flood in Utah, December 24 to 25, 2025

Area Forecast Discussion
National Weather Service Salt Lake City UT
323 AM MST Wed Dec 24 2025

.KEY MESSAGES...

- Record warm temperatures will continue through Thursday.

- Wind gusts in excess of 45 mph will continue across western Utah
  through Friday afternoon. Areas of blowing dust may reduce
  visibilities at times below 5 miles.

- 6 to 12 inches of snow is expected across the southern mountains
  above 8500 feet and western Uinta Mountains above 9000 feet
  Wednesday into late Thursday.

- Moderate to heavy rain will occur across southern Utah below 8500
  feet Wednesday into Thursday. Expect enhanced runoff across
  this area, with all streams, slot canyons, and other waterways
  running high.

- There is a less than 10 percent chance of measurable snow for
  valley floors of northern Utah Saturday morning.

- 6 to 12 inches of snow will occur across the higher terrain of
  Utah Friday into Saturday afternoon.

&&

.DISCUSSION...Deep moisture advection continues across the region
early this morning, with mesoanalysis indicating PWs have risen
from 0.20" to 0.60" over the last 24 hours across southern Utah.
PWs over 1.00" are starting to creep into southern Nevada. With
gusty southerly winds in place, many northern and western valleys
remain exceptionally warm for December. It will be another day of
recording breaking high temperatures...and potentially record high
minimum temperatures across the Beehive State.

As a jet max rounds the base of the trough to the west, deep
forcing will shift eastward into the region this morning. Note
that there is light ongoing precipitation across the southern
mountains early this morning, likely associated with an ejecting
shortwave trough ahead of the main circulation as well as the
beginning of the strongest moisture advection reaching southern
Utah.

By later this afternoon, preferential jet dynamics will combine
with near max to max PW values compared to the NAEFS climatology
to bring moderate to heavy precipitation to much of southwestern
Utah. The period of peak precipitation intensity will stretch from
around 21Z Wednesday to 12Z Thursday across southern Utah. By
Thursday evening, expect the following 25th to 75th percentile
precipitation ranges:

-Lower Washington County: 0.20-0.70"
-Zion National Park: 0.40-1.40" lower elevations, 0.70-2.00" upper
 elevations
-Pine Valley Mountains, New Harmony, Kanarraville: 2.00-4.00"
 (10% chance of 4.50"+)
-Cedar City: 0.60-1.25"

The Weather Prediction Center has outlooked portions of southern
Utah in a marginal risk for excessive rainfall, meaning a greater
than 5% chance of rainfall exceeding flash flood guidance with 25
miles of a point. CAMS suggest that embedded convection will be
ongoing from this evening into early Thursday morning, which will
bring the potential for higher hourly rainfall rates. Current
expectation is hourly rainfall rates will average around
0.10-0.40" per hour (heaviest in preferential upslope areas), with
a 10% chance hourly rates will exceed 0.50" per hour particularly
across the Pine Valleys/Zion National Park area between 22Z
Wednesday and 06Z Thursday. While flash flooding is a very low
threat (around 5-10% chance within 25 miles of a point), all area
rivers, streams, normally dry washes and slot canyons will be
running and should be avoided through at least Friday.

Snow levels overnight have been near about 8000 feet...and will
gradually rise with time as the landfalling atmospheric river
moves overhead. Expect snow levels to rise to 9000-9500 feet by
this afternoon and then fall back toward 8500-9000 feet by
Thursday morning across southern Utah. A winter weather advisory
remains in effect for elevations above 8500 feet across the
southern mountains, with 6 to 12 inches the most probable range.

Further north, deep southwesterly flow will bring moderate snow
accumulations to the western Uinta Mountains above 9000 feet, with
6 to 12 inches of snow the most probable range by Thursday
evening. Winter weather advisories also continue for this area.

With 50kts + of southwesterly flow at 700mb, gusty southerly winds
will continue through at least Thursday for the western valleys.
There is some question to the degree of momentum transfer with
ongoing precipitation and significant cloud cover, particularly
after Wednesday afternoon. HREF suggests the best chance for
multiple hours of wind gusts in excess of 45 mph will be this
afternoon and evening across the western Utah valleys (>60%,
particularly on ridgelines). By Thursday afternoon, probability
of reaching this threshold drops consistently for most locations,
except those exposed ridgelines. Will keep going wind advisory for
now, but based on the newest guidance, the threat of meeting
criteria looks to decrease after Thursday evening. Blowing dust
will also be a concern, particularly this afternoon and evening.

As the best forcing shifts eastward Thursday afternoon into
Thursday evening, attention will then turn to the colder portion
of the period. Guidance has shifted a bit...toward a splitting
system, with the main trough moving across the northern
Intermountain Region Friday evening, and a now cut-off upper level
low retrograding southwestward.

The associated cold front will shift into northern Utah Friday
evening, bringing quickly lowering snow levels in association with
a frontal band of precipitation. The heaviest period of
precipitation across northern Utah associated with this front is
expected between 00-15Z Saturday. This still provides a window
with ongoing precipitation and snow levels near valley floors
Saturday morning, however, guidance has suggested the probability
of seeing measurable snow for Wasatch Front valley floors has
decreased to around 10%. Benches will see a higher chance of
measurable snow.

For the mountains of Utah, another 6 to 12 inches of snow will be
widespread, with locally up to 15 inches for the upper Cottonwoods
by Saturday afternoon. Still a bit too early to expand the winter
weather advisories, but will likely need to consider adding
headlines with future forecast packages.

After record to near record temperatures across the region through
Thursday, with the potential for many locations to see the warmest
Christmas Day on record, more typical December temperatures are
expected by Saturday. A period of upper level ridging is
increasing in likelihood for early next week, with generally
warming temperatures.

&&

.AVIATION...KSLC...Southeasterly winds will intermittently gust
to around 20-25kts through the morning, becoming more persistent
after 18z. Blowing dust has reduced VIS to high-end MVFR this
morning, and could bounce between MVFR and VFR VIS at times at
least through the early morning hours...though confidence is low
with how this might actually unfold. Isolated rain showers will
begin to develop after 19z, with chances increasing after 03z.
CIGs are likely to drop to around 5000-6000ft AGL after 17z,
resulting in mountain obscuration.

.REST OF UTAH AND SOUTHWEST WYOMING...Gusty southerly winds can
be found in locations downwind of higher terrain this morning, and
will become more widespread in most areas after 18z. The highest
wind gusts can be expected across western valleys, with many areas
south of US-6 and west of I-15 expected to see gusts in excess of
40kts through the afternoon. Showers will develop across
southwestern UT early this morning, though may have a hard time
reaching the 5SM radius around KCDC given strong downsloping
winds. These showers will develop across northern Utah by mid-
afternoon after roughly ~19- 20z, resulting in mountain
obscuration and a low chance for periodic MVFR VIS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Wind Advisory from 11 AM this morning to 5 PM MST Friday for
     UTZ101-102-115-122.

     Winter Weather Advisory from 11 AM this morning to 11 PM MST
     Thursday for UTZ112.

     Winter Weather Advisory until 11 PM MST Thursday for UTZ125.

WY...None.
&&

Kruse/Cunningham

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