Lee cyclogenesis occurred over Colorado and low pressure moved slowly into the Plains states. Favorable east to northeasterly upslope flow brought heavy snow to portions of central Wyoming. The heaviest snow fell in the Casper area. Mesoscale banding developed in the area and brought extremely heavy snowfall rates on the morning of March 14th. A total of 15 inches of snow fell between 6 am and noon. There were widespread reports of over 15 inches of snow around Casper with a total storm total of 26.3 inches at the Casper Airport. This total was the 3rd largest storm total snowfall in station history and the largest storm total since December 1982. Heavy snow also fell in portions of Fremont, Sweetwater and Johnson Counties. The heavy snow closed many major roads, including Interstates 25 and 80 as well as US 20 26 and US 287. Some closures stretched for 3 days, stranding many travelers.

Winter Storm in GREEN MOUNTAINS & RATTLESNAKE RANGE, WYOMING
From 13-MAR-21 17:00:00 to 14-MAR-21 15:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Heavy snow and gusty winds led to the closure of many roads around the area, including US 287.

Winter Storm in BIGHORN MOUNTAINS SOUTHEAST, WYOMING
From 13-MAR-21 14:00:00 to 14-MAR-21 14:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Heavy snow fell in portions of the Eastern Bighorns. The highest total was 14 inches at the Cloud Peak SNOTEL site.

Winter Storm in WIND RIVER MOUNTAINS EAST, WYOMING
From 13-MAR-21 12:00:00 to 14-MAR-21 14:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Favorable northeasterly upslope flow brought heavy snow to the eastern slopes of the Wind River Range. The highest snow total was 26 inches at the Hobbs Park SNOTEL site. A combination of heavy snow and strong wind led to the closure of Wyoming 28 over South Pass for many hours.

Winter Storm in SOUTHEAST JOHNSON COUNTY, WYOMING
From 13-MAR-21 16:00:00 to 14-MAR-21 12:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

A combination of moderate to heavy snow and gusty wind led to the closure of roads in southern Johnson County, Wyoming, including Interstate 25.

Winter Storm in CASPER MOUNTAIN, WYOMING
From 13-MAR-21 18:00:00 to 14-MAR-21 16:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Heavy snow fell on Casper Mountain, in Natrona County, Wyoming. The Casper Mountain SNOTEL site reported 20 inches of new snow.

Winter Storm in EAST SWEETWATER COUNTY, WYOMING
From 13-MAR-21 20:00:00 to 14-MAR-21 14:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured 6 inches of snow in Wamsutter, Wyoming. The snow and wind led to the closure of Interstate 80 for a couple of days, severely effecting transportation across southern Wyoming.

Winter Storm in NATRONA COUNTY LOWER ELEVATIONS, WYOMING
From 13-MAR-21 16:00:00 to 14-MAR-21 16:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Very heavy snow fell in portions of Natrona County. The highest total reported was 26.3 inches at the Casper, Wyoming airport. Amounts dropped further west with 14 inches reported at Powder River. The storm total of 26.3 inches at the Casper Airport was the highest storm total reported since December 1982.

Winter Storm in LANDER FOOTHILLS, WYOMING
From 13-MAR-21 16:00:00 to 14-MAR-21 16:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Snowfall amounts around Lander, Wyoming, generally ranged from 6 to 12 inches, including 7.8 inches at the Lander airport.