A deadly avalanche cycle

The avalanche that killed one on Utah's Horseshoe Mountain on March 27. Utah Avalanche Center

It's been a deadly week in the backcountry around the West, with fatal incidents in Colorado, Utah and Washington and big scares elsewhere. Snow conditions have made a radical turn, with winter switching to spring in a matter of days everywhere from the Cascades to the Rockies. The afternoon sun is the common denominator in this week's incidents -- most every avalanche occurred after 12 p.m.

Last Friday, April 1, pro snowboarders Jeremy Jones and Xavier de le Rue, filmer Matt Herriger and photographer Jimmy Chin were involved in an avalanche at 2:20 p.m. on the east aspect of Shadow Peak in Grand Teton National Park, Wyoming. Chin was carried 2,000 feet in the slide and buried to his waist just as a second avalanche hurtled toward him, hitting his back and stopping there. He escaped uninjured. The group purposely triggered several slides before their descent, in attempt to ski a safer surface.

"Obviously, we checked daytime highs expected for the day," said Chin. "But we weren't totally aware of how much sun the lower slopes were getting."

Aspen's Adam Dennis, a longtime local and accomplished photographer, was killed Monday in an avalanche in the Aspen Highlands sidecountry. The slide occurred after 1 p.m. below treeline and slid to the ground. Members of the group were able to dig Dennis out within 15 minutes of the slide, but resuscitation efforts were unsuccessful.

It had snowed 14 inches Sunday night in Aspen and avalanche danger was rated as considerable for Monday and moderate below treeline, though Sunday's rating was high.

The day before, local Aspen skiers Pat Sewell, Dayla Robinson and I triggered what the Colorado Avalanche Information Center called a "very, very, very large and destructive class 5 avalanche" on a north-facing aspect of Independence Pass around 1 p.m. The slide ran 2,000 feet, and carried Sewell for 300 feet. Sewell was partially buried, but managed to dig himself out. The avalanche propagated to the ground on old, rotten layers from early in the season. The crown ranged from 2-10 feet in height.

"As we transition from a cold and dry winter snowpack into the the spring season in the backcountry, the first few warm days can create dangerous snowpack conditions," says Brian McCall from the Colorado Avalanche Information Center. "Weak layers that formed earlier in the winter become a concern again as the snowpack warms up for the first
time. Avalanche danger often peaks during the warmest times of the day, frequently between 2 and 5 pm."

In Utah, 26-year-old Garrett Smith died on March 27 from injuries he sustained in an avalanche the previous day in the backcountry on Horseshoe Mountain east of Ephraim. The group was trying to dig a snow pit to assess the snowpack when two were caught in a slide around 11:30 a.m. One of the skiers dug out another who was partially buried. They dug out Smith, who was completely buried, and administered CPR. Smith was unconscious for several hours Saturday night and died on Sunday.

In Washington, Riley McCarthy, a 20-year-old student at the University of Washington in Seattle, was killed late in the afternoon on March 27 when an avalanche in an out-of-bounds area near Stevens Pass pushed him against a tree. McCarthy's friends dug him out, but were unable to resuscitate him.

Danny Ferrari and Nate Purcell were both buried by a large avalanche on Friday near Arapahoe Basin in Colorado. The avalanche traveled 1,000 feet and carried the men about 400 feet. Purcell, 38, was partially buried and was taken to a hospital with a broken leg. He managed to use his cell phone to tell rescuers their location. Ferrari escaped uninjured despite being completely buried for 30 minutes, thanks to an air pocket he created.