A vigorous cold front and associated low pressure brought dramatic temperature and wind changes to much of western Wyoming on Saturday, December 13. The heaviest snow fell in the mountains and higher valleys of western Wyoming in advance of the arctic cold frontal surge. Mountain snowfall of six to twelve inches was common with three to six inches in the valleys. East of the Continental Divide, snowfall totals only ranged from one to three inches in the lower elevations with four to six inches in the mountains.
The strong arctic surge began around 0900MST near the Montana border and eventually reached central portions of the state between 1300 and 1500MST. The initial blast dropped above normal temperatures about 20 to 25 degrees in the first hour following frontal passage. In many locations east of the Continental Divide, the snow combined with gusty north wind of 30 to 50 mph and sharply falling temperatures, some on the order of 35 to 45 degrees over several hours, to create dangerous winter conditions. The most dangerous conditions occurred around Buffalo where winds gusted over 50 mph for almost an entire eight hour period. A peak gust of 60 mph was recorded at the Buffalo Airport and 1/4 mile visibility was reported for over four hours. This led to the closing of several roads around Buffalo. Other notable wind gusts were 63 mph at the Powell Airport and 47 mph at the Greybull Airport, both in the Big Horn Basin. Ground truth reports and webcams revealed near zero visibility due to the snow and wind, despite the limited snowfall.
The very cold temperatures and gusty wind also combined to create dangerous wind chills. By late Saturday evening, wind chill readings in the north Big Horn Basin, Johnson County, and Natrona County had fallen into the 30 below to 45 below zero range.
A four-vehicle accident occurred at 1248MST on Saturday, December 13 about five miles northeast of Cody on U.S. Highway 14A. Near zero visibility was reported at the time of the accident. A pileup on Interstate 90 north of Buffalo early Saturday afternoon involved six to eight vehicles and caused three injuries. The interstate was subsequently closed until 0430MST on Sunday. Also, two fisherman on Boysen Reservoir were stranded but survived Saturday night as they were unable to make their way back across the white-capped lake.  Waves of four to six feet made the journey to their boat launch unsafe.

Winter Storm in BIGHORN MOUNTAINS SOUTHEAST, WYOMING
From 13-DEC-08 10:00:00 to 13-DEC-08 22:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Winter Storm in TETON & GROS VENTRE MOUNTAINS, WYOMING
From 12-DEC-08 18:00:00 to 13-DEC-08 17:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Storm in JACKSON HOLE, WYOMING
From 12-DEC-08 21:30:00 to 13-DEC-08 17:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Winter Storm in STAR VALLEY, WYOMING
From 12-DEC-08 21:00:00 to 13-DEC-08 16:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in SALT RIVER & WYOMING RANGES, WYOMING
From 12-DEC-08 18:00:00 to 13-DEC-08 17:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Storm in NORTH BIG HORN BASIN, WYOMING
From 13-DEC-08 10:00:00 to 13-DEC-08 20:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Storm in NATRONA COUNTY LOWER ELEVATIONS, WYOMING
From 13-DEC-08 15:00:00 to 13-DEC-08 22:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Blizzard in NORTHEAST JOHNSON COUNTY, WYOMING
From 13-DEC-08 13:00:00 to 13-DEC-08 21:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Winter Storm in SOUTHEAST JOHNSON COUNTY, WYOMING
From 13-DEC-08 13:00:00 to 13-DEC-08 21:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways