Big , rapid warmup could trigger major avalanche cycle
By Bob Berwyn
SUMMIT COUNTY — Powerful avalanches recently tore through 100-year-old trees near Peru Creek and toppled high-voltage powerline towers that were built in the 1970s, and forecasters with the Colorado Avalanche Information Center warn that more large slides are possible during the next few days and weeks.
The super-size snowpack in Colorado’s northern and central mountains could threaten recreational backcountry travelers as well government and private industry workers in the field, said CAIC director Ethan Greene, explaining workers clearing county roads, railroad and utility workers, as well as backcountry skiers and snowmobilers all could be at risk. Click here to see the latest CAIC discussion on weather and snowpack.
The forecaster center isn’t predicting specific slides for specific areas. Instead, Greene said the forecasters wanted to give a gentle heads-up about a spring avalanche scenario that’s unprecedented in recent years. Green said there are also areas near mountain communities where homes and other structures could be threatened.
“We could slides in places you generally don’t think of as getting hit by avalanches,” he said.
There are pockets of residences throughout the Colorado mountains that were built before strict zoning laws were enacted, and some of those are situated in designated avalanche red zones. Greene said part of the idea of issuing a special bulletin was to give county managers and emergency workers a heads up about the potential dangers.
“We could see things none of us have seen before,” Greene said. “But it all depends on the weather conditions. It could all melt slowly and just runoff into the streams, but with the amount of snow we have, and some of the weak layers in the pack … if they get activated, the avalanches could be really damaging.
The culprit, of course, is an unusually deep snowpack with the potential to produce dangerous avalanches in pathways that may not have run in decades, and that may run farther than they have in recent memory.
Many of the federal government’s snow monitoring sites are recording snowpack levels of more than 160 percent of average, and include some areas with snowpack well over 200 percent of an average year. In many areas snow was still accumulating through the end of April. This may increase the likelihood for major avalanches during the melting season now underway.
The Colorado Geological Survey warns that the heavy snowpack combined with a rapid warm-up could also lead to substantial mudslides and debris flows. For instance, similar conditions in 1984 led to more than 40 mudslides and debris flows in the Vail Valley.
The CAIC also wants to remind rescue workers, demolition workers and other people that they should carry proper avalanche rescue equipment and use safe travel protocols. Staff from the Colorado Avalanche Information Center are available to advise on spring conditions and avalanche safety. Backcountry advisories are available at www.colorado.gov/avalanche through May 30th. In an emergency, staff can be reached at 303-204-6027.