If you lived in Colorado during the winter of 2019, chances are you still remember it — the relentless storms, the towering snowbanks, and the constant rumble of avalanche control bombs echoing through the mountains. That season wasn’t just snowy — it was historic.
From late February through mid-March, a parade of Pacific storms unleashed an avalanche cycle unlike anything seen in decades. Virtually every known avalanche path in Colorado ran that winter — and many new ones were discovered in the process.
From Drought to Deluge
Just a year earlier, in 2018, Colorado was locked in one of its worst droughts in modern memory. But by the spring of 2019, snowpack levels had soared well above average across nearly every mountain range.
The turnaround came thanks to a storm pattern fueled by atmospheric rivers — long, powerful plumes of Pacific moisture that stream into the western U.S. When those moisture-laden systems collided with Colorado’s rugged terrain, they dumped staggering amounts of snow.
Each storm brought one to three feet of snow, with some mountain areas seeing more than 36 inches at a time. The combination of warm, wet snow layered on top of an already deep snowpack created perfect conditions for avalanches — and the results were dramatic.
An Avalanche Outbreak for the Record Books
Between mid-February and mid-March 2019, the Colorado Avalanche Information Center (CAIC) recorded an astonishing 1,000 avalanches statewide.
Of those, 87 were rated D4 or larger — meaning they were capable of destroying trains, large trucks, or substantial stretches of forest. To put that in perspective, only 24 avalanches of that magnitude had been recorded in the entire period from 2010 to 2018.
One of the most jaw-dropping moments came in early March when a massive natural avalanche roared across Interstate 70 near Vail Pass. The slide buried the highway in snow six feet deep — and after control work brought more snow down, the total depth reached 15 feet, covering both eastbound and westbound lanes.
Farther south, Red Mountain Pass in the San Juan Mountains endured nearly three weeks of closures as snow safety crews battled constant danger. On March 10th, mitigation efforts triggered slides so immense that 40 to 60 feet of snow buried sections of Highway 550, completely filling a snow shed built to protect drivers from just such events.
The Science Behind the Storms
Several atmospheric factors aligned to make 2019 a perfect storm year.
Foremost among them were the atmospheric rivers, which funneled moisture straight into the Rockies from the Pacific. Meanwhile, a highly active Madden-Julian Oscillation (MJO) — a tropical weather pattern that influences storm tracks — enhanced lift and storm intensity over the western U.S.
Together, these phenomena fueled a series of moisture-rich storms that hammered Colorado’s mountains throughout February and March, spiking snowpack to some of the highest levels ever recorded for mid-March.
At its peak, avalanche danger maps from the CAIC lit up from High to Extreme across nearly the entire mountainous half of the state — a sight few forecasters ever expect to see.
After the Storm
By the time spring arrived, Colorado’s mountain communities had been transformed. The heavy snow erased nearly all remnants of the previous year’s drought, replenishing reservoirs and setting the stage for a lush, green summer.
But for those who witnessed the avalanches firsthand — from CDOT crews digging out buried roads to skiers watching distant slopes fracture like dominos — the winter of 2019 remains unforgettable.
It was a season that reminded Coloradans of the raw power of nature — and how quickly the mountains can shift from breathtakingly beautiful to dangerously alive.
Looking Back
The 2019 avalanche cycle stands as a stark example of Colorado’s climate extremes — how one winter can deliver both relief and destruction.
While modern forecasting and avalanche science continue to improve, one truth remains the same: when deep snow, warm storms, and steep slopes collide, Colorado’s high country can turn into one of the most dynamic and powerful environments on Earth.