April showers and spring weather bring a different ‘flavor of avalanches’ to Colorado

As the first week of April brings a storm to Colorado’s High Country, the shift from last week’s false spring back to cold temperatures and snow signals a return of winter avalanche danger. 

On Tuesday, the higher elevations across Colorado’s central mountains tipped back into moderate avalanche danger as snow hit the region, according to the Colorado Avalanche Information Center’s daily forecast.  

Brian Lazar, the deputy director of the Colorado Avalanche Information Center, said the storm is the primary driver of danger this week. 

“We’re worried about avalanches breaking in the new and drifting snow this week,” Lazar said. “And we do have the potential for some of these avalanches to break on persistent weak layers in the upper part of the snowpack.”

The most dangerous slopes will be those with wind-drifted snow, which, with a west-to-southwest storm, should be the north- and east-facing slopes, Lazar added. 

Support Local Journalism

Donate

The storm follows a week of warmer weather, where conditions transitioned toward spring in the snowpack. It’s expected that next week will swing back toward these warmer, sunny conditions. 

“It can be a complicated time as the snowpack transitions from a dry, winter-like snowpack into a more mature and ripe spring-type snowpack,” Lazar said. “But until we’ve gotten water through the entire snowpack into the ground, we’re going to be dealing with both kinds of avalanches, both cold snow and wet snow, cold dry snow, and wet snow as the weather swings wildly between winter-like weather and springtime temperatures.”

What does spring mean for avalanches? 

Spring brings a change in the “flavor of avalanches” in Colorado, Lazar said. 

“When we get into this transition to spring, what we see is an introduction of meltwater into the snowpack,” he said. “When we get prodigious amounts of meltwater into the snowpack, avalanches become more of the wet variety, which includes loose, wet avalanches, and then wet slabs.”

When this week’s storm, which could drop up to a foot of snow in some places, sees next week’s “warm temperatures and strong April sunshine for the first time, it will start to slough off and (bring) loose, wet avalanche activity,” Lazar said. 

Once the meltwater gets deeper into the snowpack, Colorado often experiences an “uptick in wet slab avalanche activity when the water reaches previously dry weak layers for the first time,” he added. 

Last week’s spring weather, which brought over 180 avalanches during the workweek, likely “took a little bit of sting” out of what the upcoming week’s warm temperatures might mean for slides, Lazar said. 

“What we saw last week is a good indication of the kinds of avalanches we’ll see next week as we get through the weekend,” he added. 

Recent weeks are fairly typical of a springtime swing in Colorado’s avalanche conditions and are something the state was already seeing in March, Lazar noted. 

In March, there were 888 avalanches in Colorado, according to the Colorado Avalanche Information Center. The vast majority (645) were naturally occurring and “loose, wet avalanches caused by the warming temperatures, Lazar noted. Humans caused 204 of the over 800 incidents. The trigger for the remainder is unknown. 

The Gunnison region saw the most avalanche reports with 294, followed by Aspen (132), the north San Juans (125), the Front Range (111), the Sawatch region (73) and the Vail and Summit County region (72). 

With these dynamic spring shifts in climate and conditions, Lazar emphasized the importance of staying on top of the forecast and being smart about where and when you head to the backcountry. 

“Once we get into more consistent warm weather, strong sunshine, predictable melt-free cycle, the general mantra for traveling in more spring-like conditions is start and end your day early because your chances of getting caught up in wet avalanche activity is much less early in the morning,” he said. 

Rounding out a ‘feast-or-famine’ season

While these conditions are typical of a Colorado spring, each winter season has its own unique characteristics when it comes to snowpack and avalanche danger, Lazar said. 

“What struck me about this year is it’s been a little bit of a hit or miss, feast or famine,” he said. “We’ve had periods of fairly dry weather interrupted by fairly potent storms. And that low elevation snow cover below about 10,000 feet has been low all year and never even really got kind of close to normal snowpack depths.”

Between Nov. 1 and April, there have been 4,118 avalanches reported by the state avalanche center. This has included 3,041 naturally occurring slides and 812 caused by human activity. There have been three fatal incidents this season. Most incidents have occurred at high elevations on north- and east-facing slopes across the state.  

The Gunnison area has seen the most avalanches, with 1,197 reported. The Aspen area takes the No. 2 spot with 905 incidents, followed by 652 in the north San Juans and 414 in the Vail and Summit County region.