High-Impact Weather and Climate Events

1977 was the driest water year on record for the Western Slope at the time, at 62% of average precipitation. 1977 also had the lowest water-year streamflows on the upper Colorado River. Both records were broken in 2002. Oct-Dec 1976 still holds as the driest Oct-Dec period in Colorado recorded history (1895-2021). The lack of snow seriously impacted the ski industry and spurred widespread adoption of snowmaking.

Drought forced 36% of municipal water suppliers to raise water rates in an effort to increase conservation. In 1977, crop losses in hardest-hit areas ranged from 40-100%. The 1976-77 winter snowpack was limited, causing economic hardship for the ski industry. The statewide summer Palmer Drought Index was -5.3, the 3rd lowest on record.

A massive, near-stationary thunderstorm dropped up to 12" of rain in 6 hours in Big Thompson Canyon, causing extreme flash flooding. Hundreds of homes were destroyed along Highway 34, and many motorists were trapped. The estimated discharge of 33,000 cfs at the canyon mouth was estimated to be a 300-year event. The most deadly natural disaster in Colorado history.

Thunderstorms and cloudburst dumped locally torrential rains over the Absaroka Range, swelling the North and South Forks of the Shoshone River. The flood damaged lodges and ranches in the area. Hail, heavy rains, and wind caused scattered crop losses along the east slopes of the Absarokas. A hailstorm and windstorm struck the Cowley-Lovell area, causing heavy crop losses. Farmers in the Heart Mountain area reported a 20 percent loss to some of their crops.

An F3 tornado first touched down at a trailer park just northeast of Gillette around 2:30 p.m., destroying 5 of 8 mobile homes and injuring one person. Straight-line winds, clocked at 75 mph at the Campbell County Airport, caused scattered damage to outbuildings and trees from Rozet eastward to Wyodak. Most of the damage was attributable to straight-line winds.

Zero-degree weather along with 40-50 mph winds caused considerable losses of newborn calves and cows.

A combination of abnormally high temperatures, rain, and strong chinook-type winds in late February and early March resulted in rapid snowmelt and flooding along the Popo Agie River. In the southern portion of Hudson, an ice jam against a highway bridge intensified the flooding and forced nearly 60 families from their homes.

Heavy rain and snowmelt caused severe flooding on Bear Creek, Turkey Creek, Plum Creek, and the South Platte River. The worst flooding in Denver since the June 1965 flood. Stapleton Airport measured 3.27" of precipitation in 24 hours.

"Weld County, Lower Latham Reservoir Dam, 1973: The failure of the Lower Latham Reservoir Dam in 1973 and subsequent flooding in the Town of Kersey, resulted in a Presidential Major Disaster Declaration." - CO Hazard Mitigation Plan 2018-2023

A widespread rain event associated with Tropical Storm Norma dropped 4-6" near Durango and Pagosa Springs and caused widespread flooding in the San Juans, including the Animas River.