An intense arctic cold front tracked rapidly from north to south across southeast Wyoming during the morning and afternoon hours on 12/21. Temperatures at the Cheyenne Airport (KCYS) fell from 43 to 7 degrees between 1:05 PM and 1:18 PM MST, before plummeting to a near-record -25 degrees F at 7:15 AM MST on 12/22.
Every event with a place to put it; 23 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 CYS wrote it up.
An intense arctic cold front tracked rapidly from north to south across southeast Wyoming during the morning and afternoon hours on 12/21. Temperatures at the Cheyenne Airport (KCYS) fell from 43 to 7 degrees between 1:05 PM and 1:18 PM MST, before plummeting to a near-record -25 degrees F at 7:15 AM MST on 12/22. Numerous records were set for the most rapid and extreme temperature drops in history. Morning low temperatures fell to -20 to -40 degrees F across a large portion of southeast Wyoming on 12/22, with many sites remaining below zero through the day. Wind chills plummeted to between -45 and -65 degrees F for many. The cold frontal passage on 12/21 was also accompanied by scattered snow showers and locally intense snow squalls, resulting in a period of extremely low visibilities and dangerous travel conditions due to a flash freeze. Several inches of mountain snow were also recorded in the Snowy and Sierra Madre mountain ranges, along with reports of significant blowing and drifting snow.
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 Cheyenne, WY wrote its last area forecast discussion before the first event at Dec 20, 9:21 PM MST, 2 hours 39 minutes earlier.
Area Forecast Discussion
National Weather Service Cheyenne WY
921 PM MST Tue Dec 20 2022
.UPDATE...
Issued at 723 PM MST Tue Dec 20 2022
Made a quick update before the start of the nighttime/early
morning forecast package later tonight. Forecast appears on track
with high winds getting going across the Arlington/Elk Mountain
area late this evening with a few gusts of 55 MPH observed so far.
These winds will continue to increase and spread eastward into
the high plains over the next 12 hours ahead of the arctic front
plunging south out of Canada. This front is just starting it's
trip south with temperatures in northern Montana lowering between
-20 to -25 over the last hour. The front is still expected to
enter the forecast area (Converse and Niobrara Counties) between 7
to 9 am Wednesday morning and then accelerate southward towards
the Colorado border through noon.
UPDATE Issued at 300 PM MST Tue Dec 20 2022
Forecast remains on track for strong winds across portions of
southeast Wyoming returning tonight, strong frontal passage
during the day Wednesday with snowfall and rapid drop in
temperatures, and the frigid arctic air leading to extremely
dangerous wind chills Wednesday night through Friday morning. This
discussion provides a quick update on these hazards with the
latest forecast package.
Decide to upgrade the High Wind Watches to Warnings beginning this
evening for the Central and South Laramie Range. Forecast models
persisted with the strong upper level flow and downward omega
across the Laramie Range and adjacent foothills. Additionally,
bumped up the start time for the remaining areas in
Carbon/Albany/Converse County to 5 AM MST with 700mb flow
increasing a little sooner with a slightly quicker arrival of the
upper level trough (will get to more about this in a moment). NBM
v4.1 probability of exceeding 48 kt gusts shows over 60% for most
of the warned area while in-house guidance continues to show
support these winds ahead of the frontal passage.
Looking at most hi-res guidance, appears that the frontal timing
as sped up by a few hours with initial entry into northern
portions of the CWA by 8 AM MST. Timing the rest out, looks to
reach the North Platte River valley (Scottsbluff/Torrington) right
around 11 AM MST and Cheyenne around 2 PM MST while crossing the
Colorado border to the east a little earlier. Hi-res guidance
continues to hint at nearly 30F degree temperature drops behind
the front in the first hour or two after its passage. Decide to
blend forecast grids more with hi-res guidance to reflect a
sharper temperature gradient and earlier arrival. This timing
will be a little more delayed west of the Laramie Range, however
forecast soundings indicate snow squall potential with around 100
J/kg of low level instability present. Winter Weather Advisories
were added for most locations Wednesday across Carbon and Albany
counties in addition to the I-25 corridor from Cheyenne to
Wheatland with the potential for a quick 1-3 inches of snowfall in
addition to the flash freeze behind the front making for slick
road conditions in the afternoon and evening hours. These
locations had more confidence in more widespread effects, but will
need to monitor radar/satellite trends tomorrow within the
advisory area and farther east into the Nebraska Panhandle as
Snow Squall Warnings may be needed for the highest intensity
snowbands. These advisories run through 5 PM Wednesday as the
frontal forcing will quick move through the CWA, however will need
to monitor for potential lingering effects with possible upslope
along the South Laramie Range. Areas around Cheyenne could see
light snowfall continuing into Wednesday evening and latest SREF
guidance even suggests higher snowfall totals could be possible.
Temperatures will continue to plunge behind the front through
Thursday morning. Latest forecast has Cheyenne dropping ~60F
degrees between early afternoon Wednesday to Thursday morning.
Latest forecast trends looked to slide the trough a little quicker
to the east displacing the core of coldest 700mb temps from our
areas. So did slightly nudge temperatures upward, but they still
remain frigid. Thursday morning lows will still be widespread 20
to 35 degrees below zero with wind chills feeling 40 to 65 degrees
below zero which will be extremely dangerous and life threatening!
Wind Chill Warnings remain in effect at this time continuing
through the day Thursday, which won't see high temperatures above
zero, and into Friday morning.
As for the long term, still looks to warm up nicely headed into
the weekend. While temperatures will drop hard late in the week,
we could be looking at a 50-60F degree temperature swing from
Friday morning to Sunday afternoon. Additionally, decide to keep
the uptick in the winds by blending in NBM 90th percentile with
strong flow aloft returning with tightening gradients and a quick
passing shortwave to the northeast.
&&
.SHORT TERM...(Today through Thursday)
Issued at 426 AM MST Tue Dec 20 2022
...EXTREMELY DANGEROUS AND POTENTIALLY LIFE THREATENING COLD WAVE
SET TO IMPACT THE REGION...FARM AND RANCH INTERESTS SHOULD MAKE
FINAL PREPARATIONS NOW...
...HIGH WINDS AND PERIODS OF SNOW AND BLOWING SNOW ALSO EXPECTED
WITH THE ARCTIC FRONT...
An active 24 to 48 hours ahead for southeast Wyoming & the western
Nebraska Panhandle w/ multiple significant, high-impact hazards to
impact the CWA. Strong winds impacting the southeast Wyoming wind-
corridors early this morning will become more widespread tonight &
Wednesday. Mountain snow is likely to develop across the Snowy and
Sierra Madre ranges later this afternoon, likely becoming heavy by
mid-day Wednesday. Widespread light to moderate snowfall is likely
along the cold front on Wednesday morning and afternoon, with some
locally intense banding & snow squalls likely. Extremely dangerous
and potentially life-threatening wind chills are likely to rapidly
develop behind the cold front with serious impacts possible to the
livestock and agricultural communities, as well as more vulnerable
human populations, especially Wednesday night through early Friday
morning.
Wind gusts of 65 to 70 MPH have been common near Arlington and Elk
Mountain early this morning. This is likely the result of enhanced
H85 CAG-CPR gradients near 70 meters between lee troughing along &
east of the Laramie Range & the surface high over western Colorado
currently in place. These gradients may diminish somewhat over the
next few hours, but steep low-level lapse rates combined w/ around
45 knots of 700-800 millibar flow should be sufficient to keep the
gusts elevated above 45-50 MPH through the day. After 00z, CAG-CPR
gradients will rapidly increase yet again as the lee trough should
intensify in response to difluent flow in advance of a significant
mid-level short wave diving into the Intermountain West. Local in-
house probabilistic guidance suggests a strong signal for gusts 60
MPH or stronger after 03z this evening, leading to the decision to
extend the current warning through 00z Thursday. Would expect this
to be cancelled a few hours early once the front passes around mid
day Wednesday. A similar scenario can be expected for the southern
Laramie Range including the I-80 Summit, with H75 flow near 60 kts
requiring High Wind Warning issuance through 11 AM MST today. Will
see a decent decrease in speeds this afternoon, but a west to east
oriented MSLP gradient on the order of 4-6 millibars will begin to
take shape between Laramie & Cheyenne after 03z this evening along
with a sharp omega couplet / mountain wave signal and 55 to 65 kts
of H7-H8 flow. This should be more than sufficient for gusts to 65
to 75 MPH overnight through mid-day Wednesday prior to the passage
of the arctic front. These winds could even spill east into Platte
County. A High Wind Watch has been issued for the Southern Laramie
Range and adjacent Foothills, as well as much of Platte County, to
include Wheatland, Glendo, and the Coleman WYDOT sensor.
Extreme MSLP gradients are expected with the passage of the arctic
front on Wednesday. Significant low-level mixing will likely occur
ahead of the boundary, with models in good agreement with 50 to 55
knots of 0.5 km flow in place across much of southeast Wyoming for
areas mainly along west of I-25. High-res model guidance including
the HRRR suggests widespread 55 to 65 MPH gusts developing between
15z and 21z prior to fropa w/ gusts decreasing to a slightly more-
manageable 30 to 40 MPH in the late afternoon & evening behind the
cold front. Have opted for a High Wind Watch from 15z Wednesday to
00z Thursday for much of southeast Wyoming given the fairly strong
support from high-res model guidance, even though this event could
be just a few hours in duration at most. All warning-criteria wind
gusts should cease immediately post-fropa, but it will remain very
windy nonetheless. In addition to the threat for high winds as the
front approaches, banded snow is likely near the frontal zone with
very strong frontogenesis at H7. This locally intense banding with
possible snow squalls could drop a quick several inches of snow w/
significant travel impacts due to blowing snow as well. This seems
like a scenario where Snow Squall Warnings may be favored over the
need for Winter Weather Advisories as the threat for precipitation
should be fairly short lived as well, so did not go w/ any winter-
precipitation hazards at this time.
The most dramatic, and likely most serious part of this storm will
be the likelihood of extremely dangerous and life threatening wind
chill values potentially exceeding 50-60 degrees below zero. Near-
record breaking high pressure is still expected to slide southward
across western Montana on Thursday w/ the GFS still suggesting the
1066 mb central pressure hear Helena which would exceed the record
for the contiguous US set in 1983. As such, this will certainly be
one of the coldest air masses to impact the area in recent years &
perhaps decades. NAEFS/EPS guidance continues to indicate both 700
and 850 mb temperatures outside of climatology with several of the
deterministic models (GFS/GEM/ECM) all showing H7 temperatures -30
deg C or colder over most of the CWA by 12z Thursday. As the cold-
front blasts south on Wednesday afternoon, high-res models suggest
that temperatures may fall 30 to 40 degrees in an hour or less. If
fropa is accompanied by a snow squall, this may be a serious flash
freeze event as well. Unlike the typical extreme cold events which
are driven by lighter winds and radiational cooling, this one will
be driven by strong winds w/ model soundings showing a deep, well-
mixed boundary layer with average flow of 25 to 35 kts expected to
reside within the lowest 1k feet AGL. That said, we could actually
see temperatures of -25 to -35 deg F with sustained winds over 25-
30 MPH! This is extremely rare and is arguably more dangerous than
your typical wind chill event where winds are less than 10 MPH. If
there are any uncertainties at all, it is exactly how cold we will
get as it is usually tough to see extreme cold when winds are this
strong. Even so, NBM v4.1 has remained very consistent with 80-100
percent probabilities of -20 F or colder actual air temperatures &
50th percentiles MinT of -24 to -34 deg F Thursday night for most,
if not all of the CWA. Official forecast was blend of 25-25-50 NBM
10th, 25th, and 50th percentiles, respectively. Prefer to hedge on
the lower side for highly anomalous air masses.
These MinT values, combined with the expected wind speeds yield WC
values under 50 degrees below zero for most zones, perhaps even as
cold as 70 degrees below zero near Lusk. Frostbite and hypothermia
can develop in mere minutes in these conditions, and unfortunately
death is a very real possibility in this scenario, especially with
more vulnerable human populations. Farmers & ranchers are strongly
advised to make final preparations to protect livestock. We cannot
stress enough the seriousness of this situation! While the coldest
wind chills will likely occur Wed night and Thu AM, highs on Thurs
will remain below zero for many with winds staying elevated. There
will not be much improvement whatsoever through Friday. Wind Chill
Watches have been upgraded to Wind Chill Warnings area-wide.
In the mountains, due to the expected significant orographics with
a 180+ knot H25 jet (90-100 knot H5 jet), high-elevation snow fall
accumulations of 8 to 15 inches will be possible in both the Snowy
and Sierra Madre ranges. This combined w/ strong winds will create
near blizzard conditions in the high country, and given the degree
of wind chills, could be very serious should anyone become lost in
these conditions. A Winter Storm Warning has been issued for these
zones through 12z Thursday, followed by a Wind Chill Warning.
.LONG TERM...(Thursday night through Monday)
Issued at 426 AM MST Tue Dec 20 2022
The main story for the beginning tier of the extended forecast
continues to be the unprecedented cold temperatures that will
stick around on Thursday night into early Friday. Model guidance
trends continue to show dangerous cold temperatures and wind
chills through Friday morning. It wouldn't be Wyoming if we didn't
also include the potential for our typical strong high winds to
ramp up again during the extended period for the wind prone
corridors as well. However, slightly above average temperatures
are favored by the end of our extended forecast into the 30s and
40s.
A dome of 1055mb surface high pressure will be firmly entrenched
across central and northern WY by Thursday evening. Brutally cold
temperatures will exist across a majority of the cwa to start the
forecast period of Thursday night. 700mb temperatures of -15C to
-25C are expected to persist across the NE Panhandle. However,
model guidance from the GFS and Canadian deterministic is
beginning to pinpoint areas where the pressure gradients are
potentially going to tighten overnight. Pressure gradients of
5-15mb over the course of six hour periods will likely result in
700mb winds approaching 45-55 knots between 0Z-12Z Friday. Omega
fields do show alternating positive and negative lift zones, and
500mb analysis depicts a mountain wave signature. It will be a
tricky overnight forecast to pin down due to the potential for
downsloping effects from the low and mid-levels warming
adiabatically overnight. We could easily see negative sub-zero
temperatures initially, and then quickly warming up into the
positive teens to potentially 20s where the strongest wind gusts
exists along and due east of the wind prone corridors. Strong
northwest flow aloft is also anticipated to create orographic
enhancement of snow showers for the Snowy/Sierra Madre mountains
as a shortwave disturbance approaches the Intermountain west from
early Friday through Friday afternoon.
The cold air will persist through Friday evening for the NE
Panhandle forecast zones as strong CAA continues to funnel into the
region. Forecast highs in the single digits to teens are expected at
this this point for the NE Panhandle. However, southeast WY will see
a rise in temperatures as downslope winds continue to adiabatically
warm a large portion of those areas. Wouldn't be surprised to see
20s to potentially near 30 degrees F in localized areas due east of
the Laramie Range on Friday, but there will be a sharp gradient.
Have not bumped up temperatures to reflect this entirely as some of
the model guidance is not in agreement with this solution presently.
WAA will occur beginning Friday night as heights in the lower and
mid-levels begin to increase thanks to an upper level ridge
amplifying. Some members of the extended guidance have a shortwave
riding along the northwest flow aloft Friday night into Saturday
afternoon. This shortwave is expected to slide to our south with
most of its energy, bringing snowfall to the mountains west of the
Laramie Range, but QPF looks low. Daytime highs will be in the 20s
and 30s on Saturday. Localized downslope warming is possible on
Saturday east of the Laramie Range thanks to gusty winds making a
return to the area. At this time of inspection, the wind prone/gap
corridors of Bordeaux and Arlington/Elk Mountain are favored for
strong winds of 50-60mph on Saturday. Additional upper level ridge
amplification is expected on Sunday into Monday, with near seasonal
to above average temperatures in the 30s and 40s. Tuesday will see
additional upper level ridge amplification, and daytime highs in
the 30s and 40s are also favored, with possible localized areas as
warm as the lower 50s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 921 PM MST Tue Dec 20 2022
Wyoming TAFS...VFR at Cheyenne until 22Z, then IFR until 02Z, then
VFR. Low level wind shear from 09Z to 20Z. Wind gusts to 45 knots
until 20Z, then gusts to 35 knots.
VFR at Laramie, except for occasional MVFR from 22Z to 01Z. Low
level wind shear until 18Z. Wind gusts to 40 knots until 18Z, then
gusts to 50 knots until 22Z, then gusts to 30 knots.
VFR at Rawlins, except for occasional MVFR from 21Z to 00Z. Low
level wind shear from 14Z to 21Z. Wind gusts to 40 knots until 14Z,
then gusts to 50 knots until 21Z, then gusts to 35 knots.
Nebraska TAFS...VFR at Scottsbluff until 18Z, then MVFR until 01Z,
then VFR. Low level wind shear until 18Z. Wind gusts to 35 knots
after 18Z.
IFR at Chadron until 13Z, then VFR, with occasional MVFR from 16Z to
20Z. Low level wind shear until 16Z. Wind gusts to 35 knots after
16Z.
VFR at Alliance, except for occasional MVFR from 17Z to 21Z. Low
level wind shear from 12Z to 17Z. Wind gusts to 35 knots after 17Z.
VFR at Sidney. Low level wind shear from 13Z to 18Z. Wind gusts to
40 knots after 18Z.
&&
.FIRE WEATHER...
Issued at 426 AM MST Tue Dec 20 2022
Extreme cold temperatures & widespread light to moderate snow
will keep fire weather concerns limited Wednesday through Friday.
&&
.CLIMATE...
Issued at 300 PM MST Tue Dec 20 2022
Widespread lows Thursday morning will likely be colder than 20F
degrees below zero for much of the CWA. Cheyenne's record low is
28F degrees below zero set in 1990, which also happens to be the last
time temperatures dropped as low as the current forecast. This is
also the December monthly low temperature. Across the Nebraska
Panhandle sites, record low temperatures are closer to 40F degrees
below zeros mostly set in 1989.
THU Lows Record
Cheyenne.... -24F -28F
Laramie..... -22F -34F
Rawlins..... -25F -32F
Scottsbluff. -26F -42F
Chadron..... -27F -40F
Alliance.... -30F -42F
Sidney...... -26F -39F
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Wind Chill Warning from 5 AM Wednesday to 11 AM MST Friday for
WYZ101>103.
Wind Chill Warning from noon Wednesday to 11 AM MST Friday for
WYZ107-108-118-119.
High Wind Warning from 5 AM to 5 PM MST Wednesday for WYZ101-104-
105-109-111-113-115-118.
Winter Weather Advisory from 9 AM to 5 PM MST Wednesday for
WYZ104>107-109>111-113-115>118.
Wind Chill Warning from 2 PM Wednesday to 11 AM MST Friday for
WYZ104>106-109>111-113-115>117.
High Wind Warning until 5 PM MST Wednesday for WYZ106-107-110-
116-117.
Winter Storm Warning until 5 AM MST Thursday for WYZ112-114.
Wind Chill Warning from 5 AM Thursday to 11 AM MST Friday for
WYZ112-114.
NE...Wind Chill Warning from 5 AM Wednesday to 11 AM MST Friday for
NEZ002-003-095-096.
Wind Chill Warning from noon Wednesday to 11 AM MST Friday for
NEZ019>021-054-055.
&&
UPDATE...TJT
SHORT TERM...CLH
LONG TERM...BW
AVIATION...RUBIN
FIRE WEATHER...CLH
CLIMATE...MBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
917 PM MST TUE DEC 20 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0656 PM HIGH SUST WINDS 1 NNW ARLINGTON 41.60N 106.21W
12/20/2022 M42 MPH CARBON WY MESONET
AVERAGE SUSTAINED WINDS AT ARLINGTON OF 42
MPH BETWEEN 700 AND 800 PM LOCAL TIME. PEAK
GUST OF 55 MPH.
&&
TTThe national radar mosaic for the moment the first event began.
19 extreme cold/wind chill, 3 winter weather, 1 winter storm. Local standard time, as filed.
Med Bow SNOTEL site (elevation 10510 feet) estimated 12 inches of snowfall with 0.6 inches of snow water equivalent. Strong winds were also being reported with areas of blowing snow.
Overnight low temperatures fell to around -25 F at multiple sites across Niobrara County from 12/21 into 12/22, with daytime highs generally remaining below -13 F during the afternoon on 12/22. Sustained winds 15-30 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 5:00 PM MST on 12/21 and 10:00 AM MST on 12/22. Minimum observed wind chill values reached -61 F at UP207 (7 WNW of Van Tassel) at 1:32 AM MST on 12/22.
Overnight low temperatures ranged from -28 F to -38 F across Converse County from 12/21 into 12/22, with daytime highs generally remaining below -10 F during the afternoon on 12/22. Sustained winds 15-30 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 8:00 PM MST on 12/21 and 11:00 AM MST on 12/22. Minimum observed wind chill values reached -60 F at DW7426 (5 WSW of Douglas) at 3:10 AM and 4:05 AM MST on 12/22, and at KDRC (Deer Creek, 1 S of Glenrock) at 6:12 AM and 7:52 AM MST on 12/22.
Overnight low temperatures fell to as low as -27 F across eastern Platte County from 12/21 into 12/22, with daytime highs remaining in the single digits below zero F during the afternoon on 12/22. Sustained winds 15-30 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 7:00 PM MST on 12/21 and 10:00 AM MST on 12/22. Minimum observed wind chill values reached -56 F at WY1 (Coleman, 13 S of Glendo) at 3:36 AM MST on 12/22.
Overnight low temperatures fell to as low as -17 F from 12/21 into 12/22, with daytime highs generally remaining below -5 F during the afternoon on 12/22. Sustained winds 10-20 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 9:00 PM MST on 12/21 and 11:00 AM MST on 12/22. A wind chill of -56 F was recorded at DODW4 (Dodge Creek, 11 miles SSE of Garrett) at 7:44 AM and 8:44 AM MST on 12/22. Minimum observed wind chill values reached -57 F at PC248 (2 NNE of Esterbrook) at 12:40 AM on 12/22.
Overnight low temperatures fell to as low as -31 F from 12/21 into 12/22, with daytime highs generally remaining below -15 F during the afternoon on 12/22. Sustained winds 15-25 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 6:00 PM MST on 12/21 and 12:00 PM MST on 12/22. Minimum observed wind chill values reached -61 F at WY44 (Shirley Rim, 2 NW of Shirley Basin) at multiple times between 5:22 AM and 8:36 AM MST on 12/22.
Overnight low temperatures fell to -24 F from 12/21 into 12/22, with daytime highs no warmer than -8 F during the afternoon on 12/22. Sustained winds 15-25 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 6:00 PM MST on 12/21 and 7:00 AM MST on 12/22. Minimum observed wind chill values reached -51 F at KBRX (Bordeaux, 9 S of Wheatland) at 3:56 AM MST.
Overnight low temperatures fell as low as -26 F at multiple sites across central Laramie County from 12/21 into 122, with daytime highs remaining in the single digits below zero during the afternoon of 12/22. Sustained winds 15-25 MPH resulted in a prolonged period of wind chills under -30 F. The most extreme wind chills occurred between 8:00 PM MST on 12/21 and 9:00 AM MST on 12/22. The Cheyenne Airport ASOS (KCYS) recorded a wind chill of -51 F at 6:53 AM MST on 12/22. Minimum wind chill values reached -56 F at WY40 (Bear Creek, 8 S of Chugwater) between 6:52 and 7:18 AM MST, and at WY46 (Cheyenne East, 9 E of Cheyenne) at 7:40 AM MST.
Overnight low temperatures fell to around -25 F at multiple sites across eastern Laramie County from 12/21 into 12/22, with daytime highs generally remaining below -10 F during the afternoon of 12/22. Sustained winds 15-30 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 11:00 PM MST on 12/21 and 9:00 AM MST on 12/22. Minimum observed wind chill values reached -67 F at UP343 (6 S of Albin) at 6:12 AM MST on 12/22.
Overnight low temperatures fell to around -25 F from 12/21 into 12/22. Sustained winds of up to 20-25 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 4:00 AM and 7:00 AM MST on 12/22. Minimum observed wind chill values reached -49 F at CAMW4 (Camp Creek, 4 W of Muddy Gap) at 6:50 AM MST on 12/22.
Overnight low temperatures ranged from -17 F to -32 F across the Laramie Valley from 12/21 into 12/22, with daytime highs generally remaining in the single digits below zero during the afternoon of 12/22. Sustained winds 10-20 MPH resulted in a prolonged period of extreme wind chills under -30 F. While the most widespread extreme wind chills generally occurred between 2:00 AM and 10:00 AM MST on 12/22, minimum observed wind chill values reached -54 F at UP345 (1 S of Rock River) from 6:17 PM until 7:32 PM MST on 12/22.
Overnight low temperatures fell to around -20 F at multiple sites across Goshen County from 12/21 into 12/22, with daytime highs remaining in the single digits below zero during the afternoon of 12/22. Sustained winds 15-25 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 8:00 PM MST on 12/21 and 11:00 AM MST on 12/22. The Torrington Airport ASOS (KTOR) recorded a wind chill of -49 F at 4:53 AM MST on 12/22. Minimum observed wind chill values reached -51 F at UP346 (15 ESE of Jay Em) at 3:15 AM MST on 12/22.
Overnight low temperatures fell as low as -27 F at multiple sites across the foothills of the southern Laramie Range from 12/21 into 12/22, with daytime highs remaining in the single digits below zero during the afternoon of 12/22. Sustained winds 10-20 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 12:00 AM and 10:00 AM MST on 12/22. Minimum observed wind chill values reached -56 F at KYWH (Wyo Hill, 10 SW of Cheyenne) at 7:50 AM MST on 12/22.
Overnight low temperatures fell to as low as -24 F across central Carbon County from 12/21 into 12/22, with daytime highs generally remaining below -10 F during the afternoon on 12/22. Sustained winds 5-15 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 12:00 AM MST and 2:00 PM MST on 12/22. The Rawlins ASOS (KRWL) recorded a wind chill of -44 F at 8:21 AM MST on 12/22. Minimum observed wind chill values reached -46 F at PC233 (Elmo, 2 NE of Hanna) at 6:30 AM MST on 12/22.
Overnight low temperatures fell to around -24 F at multiple sites near Arlington and Elk Mountain in the northern Snowy Range Foothills from 12/21 into 12/22. Sustained winds 10-20 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 5:00 AM and 3:00 PM MST on 12/22. Minimum observed wind chill values reached -54 F at WY25 (Strouss Hill, 15 NNE of Centennial) at 8:42 AM MST on 12/22.
Overnight low temperatures ranged from -14 F to -31 F across the southern Laramie Range from 12/21 into 12/22, with daytime highs generally remaining below -10 F. Sustained winds 10-20 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 1:00 AM and 12:00 PM MST on 12/22. Minimum observed wind chill values reached -65 F at PC236 (Pilot Hill, 7 E of Laramie) at 8:40 AM MST on 12/22.
Public reported near zero visibility in a snow squall with traffic impacts in Cheyenne.
WYDOT webcams showed whiteout conditions in a snow squall with mesonet observations reporting visibility below one-quarter mile and winds gusting over 70 mph along Interstate 80 near Arlington.
Trained spotter reported heavy snow and visibility less than 100 yards in a snow squall 11 miles west of Cheyenne.
Overnight low temperatures ranged from -22 F to -33 F across the Upper North Platte River Valley from 12/21 into 12/22. Minimum observed wind chill values reached -38 F at the Saratoga Airport (KSAA) at 12:35 AM MST on 12/23.
A minimum wind chill of -37 F was observed at SAWW4 (Sawmill Park, 6 WSW of Woods Landing) in the Snowy Range at 6:52 AM MST on 12/22.
A minimum wind chill of -30 F was observed at SDSW4 (Sandstone, 20 NE of Dixon) in the Sierra Madre Range at 5:00 AM MST on 12/22.
Overnight low temperatures fell to around -22 F at multiple sites across southwestern Carbon County from 12/21 into 12/22. Sustained winds around 5-15 MPH resulted in a prolonged period of extreme wind chills under -30 F. The most extreme wind chills occurred between 8:00 AM and 7:00 PM MST on 12/22. Minimum observed wind chill values reached -47 F at COWW4 (Cow Creek, 19 N of Dixon) at 11:43 AM MST on 12/22.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2022Every state in 2022This day in weather historyWarnings in Wyoming, December 2022
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: 1066250, 1062635, 1062627, 1062752, 1062650, 1062748, 1062750, 1062777, 1062778, 1062743, 1062774, 1062755, 1062776, 1062756, 1062757, 1062775, 1066251, 1066253, 1066252, 1062765, 1062773, 1062759, 1062758.