High-Impact Weather and Climate Events

"Torrential rain fell and the charred land stripped of vegetation gave way, sending a rush of mud and boulders tumbling down steep canyon walls and onto highway I-70 near Glenwood Springs. Mudslides have become more frequent and intense since the Grizzly Creek Fire scorched about 50 square miles (130 square kilometers) in the summer of 2020." - PBS News Hour

In Poudre Canyon, "flooding occurred around the burn scar of the Cameron Peak Fire, the largest recorded fire in [Colorado] history. More than 30 miles of Colorado 14, between Rustic and the intersection with Colorado 287, closed and was evacuated Tuesday after an inch of rain caused debris from the burn scar to flow downstream and flood the river." - CPR News

"A flash flood Tuesday afternoon forced the closure of Zion National Park, sending flood waters and mud through both the south entrance in Springdale and the east entrance in Kane County. State Route 9 was closed at Rockville as heavy flooding left more than a foot of mud down Zion Park Boulevard from the park entrance to Blondie’s Diner." - St. George News

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

A potent storm cycle delivered much-needed snow to northern Utah in mid-February. From February 11-18, northern Utah received 3-6” of snow-water equivalent from the Bear River Range near Logan south to the Cottonwood Canyons in the Central Wasatch. While not a quite drought-breaking storm, snow-water equivalent increased in the Bear, Provo, Six Creeks and Weber River basins by 15-20% relative to average during February. During this time period, Alta Ski Area received 103” of snow, including 65” over the last 4 days of the storm cycle. Utah Highway 210 in Little Cottonwood Canyon was closed for nearly 3 days due to extreme avalanche danger and 34 avalanches crossed the road. Avalanches occurred on many avalanche paths that had not run since 1984 and one avalanche pushed a plow truck off Highway 210.

"Feb 17: Several large slide paths in Little Cottonwood reach the highway, burying the road with debris up to 15' in places." - Utah Avalanche Center

"On the morning of February 6, 2021, two different groups (eight people total) went to ski in the Wilson Glades area of Alexander Basin on the north side of Wilson Peak in Millcreek Canyon. Both groups were ascending when the avalanche happened. Group A was near the top, and Group B was below. This avalanche was likely human triggered, but it cannot be determined by whom. Six people were caught and fully buried. Two of them survived, and four did not." - Utah Avalanche Center

The East Troublesome Fire is the second-largest wildfire in Colorado history as of 2020.

"The East Troublesome Fire was reported on the afternoon of October 14. The origination point was northeast of Kremmling in Grand County, Colo. on the Arapaho National Forest. The cause is still under investigation. Within three days, high winds and low humidity allowed the fire to spread to over 10,000 acres. The direction of fire spread threatened State Highway 125 and forced the closure of the road and mandatory evacuation of approximately 90 homes by October 17.

Between Oct. 20-23, the fire spread increased dramatically with 24-hour increases of around 18,000 to 87,000 acres during the four-day run. The peak fire spread of 87,093 acres occurred between late afternoon on Oct. 21 and the early afternoon of Oct. 22. The size of the fire exploded from 18,550 acres to 187,964 acres during this period. The fire crossed Highway 125 on the afternoon of Oct. 21 and spread eastward into the Rocky Mountain National Park on Oct. 22, crossing the Continental Divide and reaching the western edge of Estes Park on Oct. 23.

The fire was fueled by wide-spread drought, numerous dead and down beetle-killed trees, red flag weather conditions created by high winds and dry conditions, and poor humidity recovery overnight. The combination of these factors led to unprecedented, wind-driven, active fire behavior with rapid spread during the overnight hours. During this period the area north of US Highway 40 from near Granby and extending eastward to Grand Lake and Estes Park had over 7,000 structures threatened, and a population of over 35,000 placed under a mandatory evacuation.

A winter storm from Saturday, Oct. 24 through the morning of Oct. 26 brought very cold temperatures, precipitation in the form of snow and lighter winds, resulting in a dramatic drop in fire behavior with smoldering and reduced fire spread on both sides of the Continental Divide. Over this 3-day period, fire growth fell to a total of around 4,500 acres for a total of 192,457 acres. From that point forward, fire activity remained minimal with little change in area and a final total acreage of 193,812. The fire was declared contained on Nov. 30, 2020." - InciWeb

"The Mullen Fire is a wildfire that burned over 176,878 acres (71,580 ha), 28 miles (45 km) west of Laramie, Wyoming. The fire started on September 17, 2020 in the Savage Run Wilderness of Carbon County, and spread to Albany County. On September 30, it spread into Jackson County, Colorado. The cause is still under investigation. It burned close to the Rob Roy Reservoir, and Platte River Wilderness. On October 15, 2020, the fire was estimated to span 25 miles north to south, and 23 miles east to west." - Wikipedia

The wind event along the Wasatch Front was associated with the strong upper level low pressure system that brought a cold wave and snow to Colorado and Wyoming. Winds from this storm came from a northeasterly to an easterly direction. Winds from the east along the Wasatch Front cause very strong downslope winds near the base of the Wasatch Mountains. Wind gusts reach 89 mph at the University of Utah and 77 mph at the airport in Salt Lake City. The highest recorded wind speed was 99 mph in Farmington. This wind event differed from many Wasatch Front downslope wind events, because the high winds extended much further west from the mountains than is typical. Strong winds below over thousands of mature trees, damaging powerlines, structures and closing roads. Nearly 180,000 customers lost power in Utah during this storm.

The Cameron Peak Fire is the largest wildfire in Colorado history as of 2020. It is also the third most destructive wildfire in Colorado history, in terms of homes destroyed, behind the Black Forest Fire in 2013 and the Marshall Fire in 2021.

"The Cameron Peak Fire was reported on Thursday, August 13 at approximately 1:48 PM. The fire was burning in steep, rugged terrain, approximately 25 miles east of Walden and 15 miles southwest of Red Feather Lakes near Cameron Pass.

The fire burned through an area of 208,913 acres on the Arapaho and Roosevelt National Forests in Larimer and Jackson Counties and Rocky Mountain National Park.

The cause of the wildfire remains under investigation. Large scale and long duration evacuations took place throughout the fire.

During the time the Cameron Peak Fire was burning, there was another fire (East Troublesome) burning simultaneously to the west of the Cameron Peak Fire, on the west side of the Continental Divide. On October 22, the East Troublesome Fire spotted over the Continental Divide, and created what became known as the “Thompson Zone” of the East Troublesome Fire.

On the Cameron Peak Fire, extreme temperatures, low humidity, rough terrain and gusty winds reaching over 70 miles per hour were just some of the elements that contributed to extreme fire behavior and rapid rates of spread. A major contributing factor to the large fire growth was the tremendous amount of beetle kill trees and the drought-stricken Ponderosa Pine, Engelmann Spruce and mixed conifer stands available as fuel.

After 62 days of burning, on October 14, the Cameron Peak Fire became the largest recorded wildfire in Colorado's history, surpassing the Pine Gulch Fire that burned near Grand Junction in 2020.

The Cameron Peak Fire was 100% contained as of December 2, 2020." - InciWeb