2019/01/25 - Idaho - Upper Palisades Lake, Snake River Range

Published 2019/02/16 by Bob Comey - Forecaster, BTNFAC

This accident occurred in an area where the Bridger-Teton National Forest Avalanche Center provides daily avalanche hazard forecasts. Daily forecasts for this winter season began on November 2.  The accident site is located 7 miles southwest of Teton Pass and 15 miles southwest of the Jackson Hole Mountain Resort. Specialized weather stations are located at the resort and are operated by the Bridger-Teton National Forest Avalanche Center in partnership with the resort avalanche hazard mitigation program. This instrumentation includes three wind stations located at elevations of 10,450, 9,360 and 7,970 feet and four precipitation stations at elevations of 9,580, 9,360, 8,180 and 6,510 feet. Daily manual snowfall, snow water equivalent and snow height measurements are taken at all four precipitation stations to supplement automated data derived from those stations. Daily snow surface observations and weak layer tracking records are maintained at snow study plots located at these four stations. Data from these stations, and field excursions, snow pack observations and avalanche observations from the Teton Pass area were used to determine the snowpack history that preceded this event.

By mid-January this area had a snowpack that had multiple persistent weak layers of buried surface hoar and near surface faceted snow. Snow depths ranged from 2 to 4 feet. In areas where the snow was shallow the snow structure was poor. Recent new snow sat upon a base of well-developed faceted snow crystals. Buried crust layers existed within the snowpack on south facing aspects like the accident slope.

A nine day storm cycle occurred between January 16 and 25. During this period the snow study plot at an elevation of 9,580 feet received 58 inches of new snow with 5.3 inches of moisture. Slab avalanches were observed in the backcountry on all aspects and at all elevations during this storm cycle. Most failed on a layer of surface hoar and near surface faceted snow that was buried on January 16. Skies were partly cloudy the night before the accident. On January 25 cloud cover increased in the morning and snowfall developed by midday. Temperatures at 10,500 feet ranged from 6 to 13 degrees. Winds at that elevation were from the west-northwest with average speeds of 21 and gusts to 54 miles per hour.

On January 25 the general avalanche hazard rating for this area was considerable above an elevation of 7,500 feet. That day’s avalanche hazard advisory stated that avalanche conditions were dangerous and that large persistent slab avalanches and wind slab avalanches could be triggered on steep slopes by the weight of a single person. Slab avalanches were forecast to be 2 to 4 feet deep.

Two weeks earlier, on January 11, a guided helicopter skier triggered a large slab avalanche on a west facing slope at an elevation of 9,590 feet at a location that is approximately 1.5 miles southwest of the site of this incident. That skier was caught, fully buried and rescued with no injuries. The January 11 event was reported to have failed on a buried layer of surface hoar and depth hoar. The crown of that avalanche was 30 to 50 inches deep.

On January 25 a group of seven snowmobilers left a trailhead south of Victor, Idaho. They rode up Pole Canyon and proceeded into the some of the most challenging terrain in the Snake River Range. After lunch and riding in the Dry Canyon area the party split up into two groups. Group 1 was comprised of 4 riders. Group 2 was comprised of 3 riders. Later in the afternoon the first group was in an area known as Neeley Cove. Neeley Cove is located in the headwaters of the Siddoway Fork drainage of Big Elk Creek. It is high alpine terrain in two east facing cirques and is situated among some of the highest peaks in the range.

The group of four riders decided to exit the north cirque of Neeley Cove by riding up a steep south facing slope. All four had turbo based systems on their sleds. The most experienced (local terrain knowledge) rider went first. He was on his second attempt to climb the slope and achieve a ridgeline when he turned and began to ride back down the slope. The slope failed and he was caught in a large avalanche.  The avalanche barreled down the slope and hit his three companions. They lost site of the first rider as they braced for impact.

When the slide stopped all three riders at the bottom of the slide were partially buried. Two of those were buried to their waist. The third was completely buried except for one hand. The avalanche debris was soft and that third person was able to raise his head out from beneath the avalanche debris. All three were uninjured and self-extricated. The rider who set off the slide was missing. He was wearing an avalanche transceiver and a search was initiated. As they closed in on the beacon signal the searchers heard the nose of a running snowmobile beneath the surface of the avalanche debris. One of the searchers uncovered the rear bumper of that sled and then quickly uncovered the boot of their missing companion. He was buried vertically with his head down and had deployed an airbag. His head was about six feet below the surface of the avalanche debris. His helmet was packed with snow. CPR was administered; however the rider did not survive. The official cause of death was asphyxiation.

This avalanche accident was reported to have occurred sometime between 4 and 4:30 PM. At 6:12 PM a member of the group involved in the accident made it to a location where he was able to call the Bonneville County Sheriff’s Department on a cell phone.  Based on the circumstances, plans were set in motion for an organized rescue the next morning. The survivors rode back to the trailhead.

This accident occurred in technically challenging terrain during dangerous avalanche conditions. A group of rescuers, comprised only of the very best riders, made it to the site on sleds the next day. They used a rope and pulley system to pull the body of the 35-year old male uphill to a flat area where he could be removed from the site by a helicopter.

This accident occurred on the south aspect of Peak 9,670. The accident site is located approximately 1 mile east-southeast of Little Palisades Peak and ¾ of a mile west of the Idaho-Wyoming state line (Figures 1 & 2).