High-Impact Weather and Climate Events

The most damaging tornado in the history of Wyoming rapidly developed from a moderate thunderstorm and moved through the north portion of Cheyenne housing and airport areas. Damage included four C-130 aircraft and National Guard ground equipment, City-owned airport hangars and building damaged, 40 homes destroyed, 100 homes with major damage, 225 homes with lesser damage, and 17 trailer homes destroyed. One of the trailer homes was sheltering a family when it was struck, killing a 14-month old boy and severely injuring the mother and a second child.

Multiple convective rain events over a two-day period caused severe to extreme flooding on Monument Creek, Kiowa Creek, and the South Platte River.

"The most significant blizzard in Wyoming’s history in human impact occurred from January 2, 1949 to February 20, 1949. Snowfall in parts of eastern and southeastern Wyoming measured up to 30 inches, with drifts 20 to 30 feet high. Within 24 hours of the storm initiation, all bus, rail, and air traffic was halted. There were thousands of stranded motorists and rail passengers. Three thousand three hundred (3,300) miles of state highway lay in the storm area. Seventeen people perished, along with 55,000 head of cattle (approximately 15 percent of the state’s cattle) and more than 105,000 sheep. As the storm continued, Wyoming cities began to run out of food in the stores. Several other blizzards followed the first. It is estimated from field men’s reports that 4,194 people received aid through the U.S. Department of the Interior operations, and help was given to 994 ranches (Figure 4-109). Seventeen people lost their lives during the storm, the greatest loss of life documented for a Wyoming winter storm. Total economic loss is estimated at more than $9 million (more than $96 million in 2020 dollars)." - WY Hazard Mitigation Plan 2021-2026

The Blizzard of 1949 in Wyoming is popularly known as the "Storm of the Century."

Multi-day rain event caused severe flooding on Fountain Creek, Monument Creek, and the Arkansas River.

Hail from 0.5" to 2" diameter caused considerable damage to three car dealerships west of downtown and to vehicles at Warren Air Force Base.

"Larimer County, Lawn Lake Dam, 1982: The Lawn Lake Disaster of 1982 caused four deaths and over $31 million in property damage when a privately-owned dam failed in Rocky Mountain National Park above the Town of Estes Park in Larimer County. Gradual deterioration of the earthen dam led to a breach that released 220 million gallons of water. A lawsuit awarded $480,000 to the family of one of the four persons killed in the disaster." - CO Hazard Mitigation Plan 2018-2023

A record snowpack in April combined with a sudden rise in temperatures produced widespread flooding throughout the state.

A downslope windstorm along the Wasatch Front with winds of 60-80 mph. The peak gust of 102 mph recorded in Centerville. The majority of damage occured between North Salt Lake and South Ogden. Winds caused $4 million in infrastructure damage, almost entirely in Davis County, destroying hundreds of trees, powerlines, street signs and light poles. Private insured losses in Davis County alone were estimated at $64 million, mostly damage to glass, roofs, and fences. Additionally, 11 semi-trailers were knocked over on I-15. Damages resulted from wind directly and also from flying debris.

A very large winter snowpack caused extensive and sustained flooding during spring runoff.

Winter Storm Xylia. "Cheyenne, Wyoming, was buried by 30.8 inches of snow from March 13-14. According to the National Weather Service, 22.7 inches of snow fell on March 14, alone, which smashed the city's all-time single-day snow record which was set on Nov. 20, 1979 (19.8 inches). That snowstorm total was more than half of Cheyenne's average annual snowfall (60.3 inches). The National Weather Service said snowdrifts in southeast Wyoming were 5 to 10 feet high in some areas. Denver had its fourth-heaviest snowstorm on record after it piled up 27.1 inches. It was their heaviest since the March 2003 snowstorm." - The Weather Channel