High-Impact Weather and Climate Events

"On March 1, 1906, flooding along the North Platte River near Casper resulting from snow/ice melt caused a diversion dam to fail. A stream returned to its natural channel with a culvert too small to handle the flood, causing the water to rise against a railroad embankment. The embankment failed. Twelve were killed in a train wreck when the railroad bridge was damaged." - WY Hazard Mitigation Plan 2021-2026

Upslope snow event with strong northerly winds left 30" in Denver, and up to 50" on the plains east of Denver.

"What today stands as a ghost town was once a thriving settlement built along railroad tracks for the Denver, South Park & Pacific Railway. The only problem? It was built right along an avalanche slide path. On that fateful March day, 18 of the 200 residents who lived there were buried in the avalanche that swept over the town, destroying buildings and ripping up trees. Thirteen were killed, including the six children of Mrs. Marcella Doyle, who ran a boarding house for railroad men. The town was never rebuilt. Tunnel Gulch was built downgrade, out of the avalanche slide path, about a half-mile away." - 9News

The South Canyon Fire had been burning for four days when a cold front with strong and erratic winds passed over the fire, causing a blowup that killed 14 wildland firefighters within an hour of the front's arrival. The front was well-forecast but the information was not communicated to the front lines.

The Blackwater Fire was the most deadly in Wyoming history. During efforts to combat the blaze, winds caused the fire to rapidly shift direction, overrunning fire lines, killing 15 firefighters and injuring 38 others.

"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."

After five days of consistent rain caused high-flow conditions, a cloudburst occured on the Powder River, resulting in a large flood. Observers reported a 20' to 30' high wall of water, which inundated farms and ranches, killing 4,500 sheep. Eighteen people were killed when a train crashed due to a weak bridge at Cole Creek south of Casper. Peak discharge on the Powder River was approximately 100,000 cfs.

Heavy rainfall on Plum Creek headwaters caused severe flooding on Plum Creek, Cherry Creek, and the South Platte River.

"At the time of the 1864 flood what was then known as “Denver City” rested on the northeastern banks of Cherry Creek. A snowy winter, heavy spring rain and an unusually violent thunderstorm caused horrendous flash flooding along Cherry Creek. Pioneers had built in the dry bed of Cherry Creek, despite warnings by Arapaho Chief Little Raven. One night a six-foot wall of water came crashing down the creek. The flood killed 15 to 20 people and did an estimated $1 million worth of property damage. Today, American Historian, Dr. Tom Noel, notes, in writing for the Denver Post, “Learning a lesson from that great flood and several others that followed it, Denverites have given Cherry Creek much more room with a walled channel, a greenway and a grassy tree lined boulevard. As Coloradans rebuild, consider giving all our waterways plenty of roomy green space." - Mile High Flood District

Moisture from the remnants of Hurricane Linda spread into the Southwest and intersected with a strong upper-level trough, sparking isolated heavy thunderstorms. Two successive storms passed over Hildale between 2:00 pm and 5:00 pm, dropping an estimated 2" in rain. This caused two flood peaks on Short Creek in Hildale, the second of which swept away two vehicles with 16 people inside, 13 of whom drowned. The second storm also produced heavy rain in Zion National Park, about 15 miles north of Hildale, causing a flash flood in Keyhole Canyon that killed seven park visitors who were canyoneering. Another motorist 15 miles west of Hildale was swept away and killed by flooding the same day.

By some measures, this is still the most costly and destructive flood event in Colorado history. Intense thunderstorms near Castle Rock dropped over 14" of rain in several hours, causing extreme flooding on Plum Creek, Cherry Creek and the South Platte River. The flood zone included two-thirds of Denver's industrial area. The Purgatoire River and lower Arkansas River also experienced severe flooding; 11" of rain fell at Holly and over 15" near Lamar in one day.