A potent winter storm system brough widespread heavy snow across the Utah mountains, and the northern and central valleys, as well as strong winds.
Every event with a place to put it; 19 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SLC wrote it up.
A potent winter storm system brough widespread heavy snow across the Utah mountains, and the northern and central valleys, as well as strong winds.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Salt Lake City, UT wrote its last area forecast discussion before the first event at Dec 13, 11:18 PM UTC, 2 hours 12 minutes earlier.
Area Forecast Discussion
National Weather Service Salt Lake City UT
418 PM MST Mon Dec 13 2021
.SYNOPSIS...Gusty winds are expected ahead of a significant winter
storm which will impact much of the state Tuesday into Wednesday.
The active pattern will continue into the weekend.
&&
.SHORT TERM (Through 00Z Thursday)...Much of Utah will experience
a significant winter storm Tuesday into Wednesday. There's a lot
to discuss with this system.
A strong upper level trough is currently approaching the Pacific
Coast. Meanwhile, a significant atmospheric river event is ongoing
across portions of northern and central California. Ahead of this
system, deep and strong southwesterly flow continues, with gust up
to 45 mph being reported across the western valleys.
As this strong trough begins to shift eastward into the Great
Basin Tuesday, 700mb winds will increase to near 50 to 60kts by
Tuesday morning across western Utah. There is some question as to
how early these will be realized at the surface and how strong
they will be at the surface. Much of the guidance supports gusts
to 60 to 65 mph as early as 6 AM across the western
tier...including the Tooele Valley, with advisory level winds with
gusts to 55 mph along the I-15 corridor.
Attention will then turn to the precipitation portion of this
system. Given the linkage to the atmospheric river is relatively
uninterrupted as the system moves across Utah, this should provide
an increased level of available atmospheric moisture. The cold
front is expected to cross the state from west to east Tuesday
evening through early Wednesday morning. As the upper level low
crosses the Utah/Arizona border region, a period of cyclogenesis
is expected Tuesday night into Wednesday morning, with the
potential for wrap around precipitation/isentropic upglide
Wednesday morning into Wednesday afternoon. Confidence in the
location of this potential band of precipitation in the very cold
air (and thus potential for heavier accumulations of snow) is low
at this point, but may impact portions of the I-15 corridor
Wednesday morning.
For the mountains, initial high moisture content snow will shift
to low moisture content snow with the passage of the front. 700mb
temperatures will decrease from ~-4C Tuesday evening to ~12C
Wednesday morning. Looking like 10 to 18 inches with locally
higher amounts particularly in the Cottonwood Canyons and the Pine
Valleys.
For the valleys, expect rain ahead of the front, with a transition
to snow Tuesday night. With how cold temperatures will be in the
wake of the front, any wet roads/standing water may freeze by
Wednesday with a layer of accumulating snow on top. This may
present particularly hazardous driving conditions for the
Wednesday morning commute across the Wasatch Front and other
western valley locations. One location that is somewhat unusual
will be Zion National Park, where accumulating snow is expected
Tuesday night into Wednesday morning. Currently do not expect more
than grassy accumulation at best for the St. George area, but this
is something to monitor over the next 24 hours.
Expect a period of gusty winds across southeastern Utah ahead of
the front Tuesday night into Wednesday morning. These winds may
approach advisory criteria along US-89 between Kanab and Lake
Powell as well as the greater Lake Powell area. Confidence is not
sufficient to issue a wind advisory for these locations with this
package but something to monitor going forward.
A wide variety of high wind warnings (western valleys), winter
storm warnings (all mountains of Utah) and winter weather
advisories (most valley locations of Utah and Uinta County, WY)
have been issued with this package.
.LONG TERM (After 00Z Thursday)...An active weather pattern will
remain in place across the region the latter half of the work week
and over the weekend with multiple rounds of precipitation
forecast. Wednesday evening looks to remain fairly breezy for
eastern Utah areas as the influence of low pressure tracks away
from the region. Cluster model forecast analysis for Thursday are
in good agreement with one another with a broad area of low
pressure over the Pacific Northwest. Mountain snow is likely with
valley snow possible throughout much of the day. Snow amounts in
the mountains range from 1 to 7 inches with 1 to 2 inches possible
in the valleys. There are uncertainties pertaining to the
snowfall amounts as the NBM guidance is showing areas of higher
snowfall probabilities. NBM guidance 50th percentile indicates 2
inches for locations like Ogden and Hill AFB, which is similar to
WPC output. 90th percentile ranges upwards of 5 inches.
On Friday, a relatively dry cold front looks to sweep across the
area. Cluster analysis remain in good agreement showing a chance
for snow across northern Utah. Any accumulations look to be light
in the mountains and no more than a few inches. The primary impact
for Friday will be increasing northerly winds in southwest Utah.
Gap winds may develop along I-15 in southwest Utah Friday
afternoon into the evening, allowing for strong wind gusts.
Over the weekend, bitterly cold temperatures arrive Saturday
morning. Single digit lows are forecast across much of the state
with low teens forecast along the Wasatch Front. Cluster analysis
show fairly low agreement on the progression of an area of low
pressure to our south. Several cluster models indicate the
presence of a trough of low pressure to our north by Sunday with
one showing a trough to our west and one cluster building in a
ridge of high pressure. What is in agreement however, is that the
deterministic and ensemble GFS both indicate weak atmospheric
moisture passing through Utah Sunday. NBM solution over the
weekend is to place low end chances for light snow Saturday
evening into Sunday, mostly for northern Utah areas. By Monday of
next week, a ridge of high pressure may build in and dry out
conditions temporarily.
&&
.AVIATION...KSLC...VFR conditions will transition to MVFR/IFR
conditions through the valid TAF period. CIGs will generally
remain above 7kft ahead of an approaching storm/cold front. Rain
will preclude the front from 21-00Z. After the frontal passage
(~00Z) rain will quickly transition to snow, which will be heavy
at times and could reduce VISBY to IFR. Winds will be quite strong
and out of the south ahead of the strengthening storm. Sustained
winds will be between 12-20 kts with gusts between 20-35 kts,
potentially nearing 40 kts by 18Z tomorrow. LLWS is also possible
ahead of this storm as surface winds and 2000 ft AGL winds could
vary enough to create some low-end LLWS mainly during the
overnight/morning hours when surface winds are lightest.
REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail
across the the region through the valid TAF period. Clouds will
generally remain above 7 kft, but will be dropping ahead of a
strengthening storm/cold front approaching from the west that
will approach western Utah by 18Z tomorrow. Winds ahead of this
storm will be quite gusty. Sustained southerly winds will range
between 15- 25 kts with gusts between 30-40 kts. LLWS is also
possible ahead of this storm as surface winds and 2000 ft AGL
winds could vary enough to create some low-end LLWS ahead of the
frontal passage, mainly during the overnight/morning hours when
surface winds are lightest. Rain will start to impact southern and
western TAF sites by 21Z tomorrow.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory from 11 PM Tuesday to 11 AM MST
Wednesday for UTZ102>109-115-116-118-119-122-126-127.
Wind Advisory from 6 AM to 6 PM MST Tuesday for UTZ105-116-119-
126-127.
High Wind Warning from 6 AM to 6 PM MST Tuesday for UTZ101-102-
115-122.
Winter Weather Advisory from 2 AM to 11 AM MST Wednesday for
UTZ124-128-129.
Winter Storm Warning from 5 PM Tuesday to 11 AM MST Wednesday
for UTZ110>113-117-125.
WY...Winter Weather Advisory from 11 PM Tuesday to 11 AM MST
Wednesday for WYZ021.
&&
Kruse/NDeSmet/Wilson/Mahan
For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecity
For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.phpThe national radar mosaic for the moment the first event began.
14 heavy snow, 5 high wind. Local standard time, as filed.
Automated weather station wind gusts included 67 mph at State Route 112 at Milepost 6 Utah Avenue, 60 mph at both Warner and State Route 36 at Milepost 49 Stockton Bar, and 58 mph at Bolinder Field-Tooele Valley Airport.
Automated weather station wind gusts included 71 mph at Upper Cedar Mountain, 62 mph at Simpson Springs, and 60 mph at Durand Road.
Automated weather station wind gusts included 75 mph at Kennecott Marina, 63 mph at Interstate 215 at Olympus Cove, and 58 mph at Mouth of Parleys.
The Cedar City Regional Airport automated weather station recorded a peak wind gust of 67 mph. Other automated weather station wind gusts included 60 mph at Hamiltons Fort and 62 mph at Black Ridge.
The King Canyon automated weather station record a gust of 68 mph.
Storm total snow amounts included 15 inches in Tooele, 12 inches in Grantsville, and 10 inches in Stansbury Park.
Storm total snow amounts included 7.5 inches in Brigham City and 6 inches in Garland.
Storm total snow amounts included 14 inches in Bountiful, 12 inches in both North Salt Lake and Clearfield, and 9.7 inches in Fruit Heights.
Storm total snow amounts included 18 inches in Cottonwood Heights, 14.8 inches in Sandy, 14 inches in Millcreek, 13 inches in both Holiday and Sugarhouse, 12 inches in West Valley City, and 8.5 inches at salt Lake City International Airport.
Storm total snow amounts included 12 inches in both Payson and Santaquin, and 6 inches in both Spanish Fork and Lehi.
Storm total snow amounts included 10 inches in Hyrum, 9 inches in both Logan and Richmond, and 8 inches in Nibley.
Precipitation amounts included 1.5 inches of snow water equivalent, or approximately 21 inches of snow, at Little Bear SNOTEL and 1.2 to 1.4 inches of snow water eqvuivalent, or 15 to 18 inches of snow, at Louis Meadows, Farmington and Parish Creek SNOTELs.
Storm total snow amounts included 23 inches at Snowbird, 22 inches at Alta Ski Area, 17 inches at Big Cottonwood Spruces, and 13 inches at Solitude Mountain Resort.
Precipitation amounts included 1.6 inches snow water equivalent, or approximately 22 inches of snow, at Sprit Lake SNOTEL and snow water equivalent of 1.2 to 1.3 inches, or approximately 17 of 18 inches of snow, at Five Points Lake, Chepeta, Lakefork Basin, Redden Mine, and Brown Duck SNOTELS.
Precipitation amounts included 1.3 inches of snow water equivalent, or approximately 18 inches of snow, at Indian Canyon SNOTEL, and snow water equivalent of 1.0 to 1.1 inches, or approxmiately 13 to 14 inches of snow, at Mammoth-Cottonwood and Timberline SNOTELs.
Storm total snow amounts included 10 inches in Oak City, and 6 inches in both Desert and Delta.
Sorm total snow amounts included 10 inches in Fillmore, 7.2 inches in Levan, and 6 inches in Nephi.
Precipitation amounts included snow water equivalent of 2.0 to 2.2 inches, or approximately 27 to 31 inches of snow, at Mt Baldy and Pine Creek SNOTELs, and 1.0 to 1.4 inches of snow water equivalent, or approximately 14 to 16 inches of snow, at Oak Creek, Buck Flat, and Farnsworth Lake SNOTELs.
Precipitation amounts included 1.6 inches snow water equivalant, or approximately 22 inces of snow, at Big Flat, Long Flat, and Cedar Breaks SNOTELs and 1.1 to 1.4 inches of snow water equivalent, or approximately 15 to 18 inches of snow, at Clayton Springs, Yankee Reservoir, Kimberly Mine, Donkey Reservoir, Harris Flat, Widtsoe, and Sunflower Flat SNOTELs.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2021Every state in 2021This day in weather historyWarnings in Utah, December 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 999547, 999546, 999551, 999556, 999553, 999324, 999326, 999327, 999328, 999329, 999330, 999332, 999333, 999334, 999335, 999337, 999338, 999340, 999341.