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.

Extreme Cold/Wind Chill in CONVERSE COUNTY LOWER ELEVATIONS, WYOMING
From 21-DEC-22 09:36:00 to 23-DEC-22 05:50:00 (MST-7)
Reported by: Mesonet

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.

Extreme Cold/Wind Chill in LARAMIE VALLEY, WYOMING
From 21-DEC-22 14:22:00 to 23-DEC-22 03:53:00 (MST-7)
Reported by: Mesonet

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.

Extreme Cold/Wind Chill in SOUTH LARAMIE RANGE, WYOMING
From 21-DEC-22 15:20:00 to 23-DEC-22 05:00:00 (MST-7)
Reported by: Mesonet

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.

Extreme Cold/Wind Chill in NIOBRARA COUNTY, WYOMING
From 21-DEC-22 09:34:00 to 23-DEC-22 09:52:00 (MST-7)
Reported by: Mesonet

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.

Extreme Cold/Wind Chill in NORTH LARAMIE RANGE, WYOMING
From 21-DEC-22 10:20:00 to 23-DEC-22 02:44:00 (MST-7)
Reported by: Mesonet

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.

Extreme Cold/Wind Chill in SOUTH LARAMIE RANGE FOOTHILLS, WYOMING
From 21-DEC-22 14:44:00 to 23-DEC-22 01:00:00 (MST-7)
Reported by: Department of Highways

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.

Extreme Cold/Wind Chill in CENTRAL LARAMIE COUNTY, WYOMING
From 21-DEC-22 13:06:00 to 23-DEC-22 04:07:00 (MST-7)
Reported by: Department of Highways

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.

Extreme Cold/Wind Chill in FERRIS/SEMINOE/SHIRLEY MOUNTAINS, WYOMING
From 21-DEC-22 13:50:00 to 22-DEC-22 09:50:00 (MST-7)
Reported by: RAWS

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.

Extreme Cold/Wind Chill in SHIRLEY BASIN, WYOMING
From 21-DEC-22 11:50:00 to 23-DEC-22 03:22:00 (MST-7)
Reported by: Department of Highways

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.

Extreme Cold/Wind Chill in EAST LARAMIE COUNTY, WYOMING
From 21-DEC-22 13:15:00 to 23-DEC-22 06:58:00 (MST-7)
Reported by: Mesonet

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.

Winter Storm in SNOWY RANGE, WYOMING
From 21-DEC-22 00:00:00 to 22-DEC-22 04:00:00 (MST-7)
Reported by: SNOTEL

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.

Extreme Cold/Wind Chill in CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY, WYOMING
From 21-DEC-22 12:26:00 to 22-DEC-22 12:22:00 (MST-7)
Reported by: Department of Highways

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.

Extreme Cold/Wind Chill in EAST PLATTE COUNTY, WYOMING
From 21-DEC-22 10:10:00 to 23-DEC-22 08:08:00 (MST-7)
Reported by: Department of Highways

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.

Winter Weather in CENTRAL LARAMIE COUNTY, WYOMING
From 21-DEC-22 15:20:00 to 21-DEC-22 15:30:00 (MST-7)
Reported by: Public

Public reported near zero visibility in a snow squall with traffic impacts in Cheyenne.

Winter Weather in SOUTH LARAMIE RANGE FOOTHILLS, WYOMING
From 21-DEC-22 15:44:00 to 21-DEC-22 15:50:00 (MST-7)
Reported by: Trained Spotter

Trained spotter reported heavy snow and visibility less than 100 yards in a snow squall 11 miles west of Cheyenne.

Extreme Cold/Wind Chill in GOSHEN COUNTY, WYOMING
From 21-DEC-22 14:23:00 to 23-DEC-22 05:44:00 (MST-7)
Reported by: Mesonet

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.

Extreme Cold/Wind Chill in CENTRAL CARBON COUNTY, WYOMING
From 21-DEC-22 15:00:00 to 23-DEC-22 03:53:00 (MST-7)
Reported by: Mesonet

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.

Winter Weather in NORTH SNOWY RANGE FOOTHILLS, WYOMING
From 21-DEC-22 15:26:00 to 21-DEC-22 15:44:00 (MST-7)
Reported by: Department of Highways

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.

Extreme Cold/Wind Chill in NORTH SNOWY RANGE FOOTHILLS, WYOMING
From 21-DEC-22 15:06:00 to 23-DEC-22 04:42:00 (MST-7)
Reported by: Department of Highways

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.

Extreme Cold/Wind Chill in SOUTHWEST CARBON COUNTY, WYOMING
From 22-DEC-22 05:30:00 to 22-DEC-22 23:10:00 (MST-7)
Reported by: RAWS

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.

Extreme Cold/Wind Chill in SIERRA MADRE RANGE, WYOMING
From 22-DEC-22 04:00:00 to 22-DEC-22 06:00:00 (MST-7)
Reported by: RAWS

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.

Extreme Cold/Wind Chill in UPPER NORTH PLATTE RIVER BASIN, WYOMING
From 22-DEC-22 02:55:00 to 23-DEC-22 02:00:00 (MST-7)
Reported by: AWOS

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.

Extreme Cold/Wind Chill in SNOWY RANGE, WYOMING
From 22-DEC-22 03:52:00 to 22-DEC-22 20:52:00 (MST-7)
Reported by: RAWS

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.