An upper level disturbance moved across Wyoming. The disturbance tightened the pressure gradient across the area. In addition, favorable jet dynamics mixed strong mid level winds to the surface and brought high winds to much of the area. Many locations had wind gusts over 58 mph with several locations having hurricane force wind gusts. Some of the more notable gusts included 91 mph along the Chief Joseph Highway, 79 mph at Buffalo, Wyoming, 75 mph south of Casper, Wyoming and 66 mph at the Rock Springs airport. At Cody, Wyoming, numerous trees were downed, some up to two to three feet in diameter. One tree fell on a house, causing extensive roof damage. The strong winds led to transportation problems as well with road closures and bans on high profile vehicles, including along Interstate 80.

High Wind in ABSAROKA MOUNTAINS, WYOMING
From 20-DEC-20 04:00:00 to 20-DEC-20 16:52:00 (MST-7)
Magnitude: 79.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

A prolonged period of high wind occurred along the Chief Joseph Highway in Park County, Wyoming. Sustained winds of over 60 mph occurred for several hours. There were also numerous wind gusts over 75 mph including a maximum gust of 91 mph.

High Wind in NATRONA COUNTY LOWER ELEVATIONS, WYOMING
From 19-DEC-20 03:44:00 to 20-DEC-20 16:12:00 (MST-7)
Magnitude: 65.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

High winds occurred in the wind prone areas near Casper, Wyoming. The highest wind gusts reported was 75 mph along Wyoming Boulevard to the south of Casper, Wyoming. The wind lead to the closure of roads to high profile vehicles for several hours.

High Wind in CODY FOOTHILLS, WYOMING
From 20-DEC-20 01:01:00 to 20-DEC-20 15:56:00 (MST-7)
Magnitude: 63.00 MG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Mesonet

Wind gusted as high as 72 mph in the Cody Foothills. In Cody, Wyoming, the high winds downed trees, some as much as 2 to 3 feet in diameter. One of the trees fell through the roof of a house.

High Wind in UPPER WIND RIVER BASIN, WYOMING
From 20-DEC-20 04:55:00 to 20-DEC-20 05:55:00 (MST-7)
Magnitude: 35.00 MS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Winds were sustained at 40 mph at the Dubois, Wyoming airport.

High Wind in NORTHEAST JOHNSON COUNTY, WYOMING
From 20-DEC-20 10:53:00 to 20-DEC-20 13:08:00 (MST-7)
Magnitude: 69.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

High wind occurred in northern Johnson County, Wyoming. The highest gust was 79 mph at the Buffalo, Wyoming airport. Wind gusts up to 65 mph occurred along Interstate 90. As a result, the Interstates 25 and 90 were closed to high profile vehicles for several hours on the 20th.

High Wind in EAST SWEETWATER COUNTY, WYOMING
From 20-DEC-20 12:44:00 to 20-DEC-20 21:44:00 (MST-7)
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

High winds occurred in eastern Sweetwater County, Wyoming. The highest wind gust was 66 mph at the Sweetwater County, Wyoming airport. The high winds impacted transportation by closing Interstate 80 to high profile vehicles for several hours.

High Wind in WIND RIVER BASIN, WYOMING
From 20-DEC-20 13:31:00 to 20-DEC-20 13:46:00 (MST-7)
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winds gusted as high as 64 mph at Pavillion, Wyoming.