CAIC Warns of Wet-Snow Avalanches
by Watch Staff
May 10, 2011 | 3401 views | 0 0 comments | 7 7 recommendations | email to a friend | print
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A WET SLAB avalanche on April 30 swept into Peru Gulch near Montezuma, Colo., destroying a high-voltage tower that had been in place since the 1970s. The Colorado Avalanche Information Center warns that large, destructive spring avalanches are a real possibility this spring. (Courtesy photo)
Deep Snowpack Creates Potential for More Powerful, Dangerous Slides

SAN JUAN MOUNTAINS – Winter may be done, but the Colorado Avalanche Information Center has taken the unusual step this spring of issuing a caution regarding large, wet-snow avalanches.

CAIC Director Ethan Greene sent out a press release last week that began, “Unusually deep snowpack in parts of Colorado’s northern and central mountains has 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.”

While the southwestern part of the state lagged behind the northern and central mountains in snow depth for most of the winter, heavy snows in April have added to the potential for large, wet-snow slides here as well. Wet releases can be exceptionally destructive. Spring slides caused miners in turn-of-the-century Ophir to build their cabins on large beams, like sled runners, instead of solid foundations, in hopes the slides running out of Spring Gulch would shove their homes along rather than crush them.

Greene’s warning was for “public workers, fieldworkers [and] recreationists” to look out for “larger, stronger avalanches in uncommon locations.”

The text of the release follows:

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 CAIC emphasizes that the public – including local governments and private companies that deploy fieldworkers to outdoor sites – need to be aware of this potential hazard and be prepared for very large events. This warning also applies after an avalanche, as it is important people do not enter debris zones until the area has been evaluated for further avalanche activity potential.

An example of this hazard occurred April 30, when an unusually large and destructive avalanche struck the Peru Creek drainage near the town of Montezuma in Summit County. This avalanche destroyed large, 100-plus year-old trees as well as a high-voltage tower that was installed in the late 1970’s. This was an isolated event, but an indication of what is possible this spring. In addition, 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.

While rapid transition to above freezing temperatures, or a sustained period of warm temperatures could produce very large and damaging avalanches, large spring avalanches are not guaranteed. But the right weather conditions during May and early June could produce avalanches larger than we have seen in 30 to 100 years. Stands of timber, structures, and other assets in avalanche runout areas could be damaged or destroyed.

The CAIC 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 30, complete with a map showing SNOTEL (federal Natural Resources Conservation Service) data on snowpack levels and photographs showing recent impacts of the Peru Creek drainage avalanche. In an emergency, staff can be reached at 303-204-6027.

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