Detailed Accident Report

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Date: 2009-02-27
Submitted By: BTNFAC
Place: Indian Peak area of the Snake River Range in western Wyoming
State: WY
Country: USA
Fatalities: 3
Summary: 4 snowmobilers caught, and buried. 1 self-rescued, 3 killed

***OFFICIAL REPORT***

Also visit www.jhavalanche.org for a report with photos

Avalanche Accident Report

Accident and Rescue Summary

On February 27, 2009 four snowmobilers were caught in an avalanche in the Snake River Range of Western Wyoming. This incident occurred in Lincoln County, Wyoming about four miles east of the Idaho State Line and two miles south of the Teton County Line. The snowmobilers; Robert Clark (age 48), Scott Smith (age 45), Wade Clark (age 53) of Soda Springs, Idaho and Bob Tiechert (~age 55) of Grace, Idaho were descending into the top of the Dry Fork Drainage of Wolf Creek from a ridgeline between Red Mountain and Indian Peak near Peak 9,563. They accessed this area from a trailhead in the Wolf Creek Drainage along Highway 89 in the Snake River Canyon.

The four riders dropped off of the ridge and descended in a southeasterly direction between a steep south facing hillside and a cliffy north facing slope. The avalanche released after the last member of the party entered the drainage and propagated across a south facing aspect and overwhelmed all four members of the party. Three men were completely buried and the other was partially buried with one arm above the snow surface.

The partially buried person, Wade Clark, was able to dig himself out and hiked uphill to get cell phone service and call for help. This effort took about an hour. Search and Rescue teams were reported to have responded at 2:22 PM. Rescue personnel from Lincoln and Teton County responded. Teton County Search and Rescue personnel used a helicopter to deploy 12 explosive hand charges on the north facing slope above the incident site to secure the area.

The three victims were located by search and rescue personnel with transceivers under three to five feet of avalanche debris. Two of the snowmachines were fully buried and the other two were partially buried. The three victims were located within 12 feet of the two partially buried sleds. The bodies were flown from the site by helicopter that afternoon. The Lincoln County Coroner determined the cause of death to be compression asphyxiation.

A photograph of the avalanche site is available in the snowpack summary section of the Bridger-Teton National Forest Avalanche Center website at ……

Avalanche Data

This soft slab avalanche (SS-AM-3-0-24”) failed on a hard crust on a southerly aspect from an elevation of 9,400 feet. The debris at the toe of the slide ran to an elevation of about 8,600 feet. The running length of the avalanche is estimated to have been approximately one half mile. The depth of the crown was reported to have averaged 18 to 24 inches deep and may have been up to three feet deep in places. The crown of the avalanche propagated approximately one half mile in a jagged line along the south facing slope above the snowmobilers. The debris from this slide accumulated to a depth of about 10 feet in the terrain trap formed by the surface drainage feature underneath this slope.

Weather and Snowpack

This incident occurred on Friday afternoon. On the previous weekend skies were clear and a strong temperature inversion developed under a ridge of high pressure. Daytime highs on Saturday and Sunday rose into the mid 30’s. These conditions likely created a sun crust on the south facing slope where this avalanche occurred. During the week a low pressure system located off of the Oregon coast ejected pulses of moisture into the area and on Thursday this system moved inland and over the region. From Sunday to Friday the Jackson Hole Mountain Resort received 18” inches of new snow with 1.8 inches of moisture at the Rendezvous Bowl snow study plot at an elevation of 9,580 feet. This study plot is located 25 miles north of the accident site. Winds at 10,500 feet were southwesterly at 18 to 30 miles per hour with gusts to 68 miles per hour during the four days prior to this incident. Temperatures at 9,000 feet were in the 20’s on Monday, the teens and mid 20’s on Tuesday and in the teens on Wednesday and Thursday. On Friday morning at 5AM temperatures at 9,000 feet were in the single digits below zero. Skies cleared as the day progressed and daytime highs rose into the upper teens to low 20’s.

Daily backcountry avalanche hazard forecast bulletins are issued for this area by the Bridger-Teton National Forest Avalanche Center. On Friday February 27, 2009 the general avalanche hazard was moderate. The advisory reported five inches of new snow and strong west-southwest winds during the previous 24 hours. It stated “West-southwest winds have formed new soft slabs to two feet in depth on leeward aspects. These surface slabs could be human triggered by humans who venture into steep avalanche starting zones with fresh deposits of wind-blown snow”

***MEDIA REPORTS***

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Victims of slide carried beacons

By: Angus M. Thuermer Jr., Jackson Hole News and Guide

Date: March 2, 2009

All four members of a snowmobile party that was hit by a deadly avalanche Friday in the Snake River Range were wearing avalanche transceivers, Lincoln County officials said.

The slide occurred in the Deadhorse Creek drainage, the county sheriff’s department said in a news release issued Saturday, killing three men by compression asphyxiation.

Officials identified the deceased as Robert Clark, 48, and Scott Smith, 45, both of Soda Springs, Idaho, and Bob Tiechert, about 55, of Grace, Idaho.

Wade Clark, 53, of Soda Springs, Idaho, the brother of Robert Clark, was the survivor. He dug himself out from the snow and hiked uphill to get cell phone service and call for help, according to Sgt. Shane Tindall of the Lincoln County Sheriff’s Office.

The slide ran between a half-mile and a mile, Tindall said, and buried the snowmobilers under 3 feet of snow. Wade Clark said he was buried, as well, Tindall said, but managed to dig himself out.

There was no immediate information how long Wade Clark was buried or why he was not able to locate his partners with his transceiver. Tindall said only that the survivor reported being cold and shaking.

The survivor climbed “by his estimate, about an hour before he was high enough to get service,” for his cell phone, Tindall said. Search and rescue teams responded at 2:22 p.m., according to the agency’s news release. Both Star Valley and Teton County search and rescue teams were deployed from a base in the Snake River Canyon near Wolf Creek.

Using a Teton County helicopter, crews found Wade Clark and the avalanche site. They rescued him and set off explosives to reduce the chance of additional avalanches on the slide path.

Searchers then found the three victims using transceivers, battery-powered transmitters worn by skiers and snowmobilers to speed the chance of being located or locating a buried victim. The victims were retrieved that afternoon and the cause of death subsequently determined by the Lincoln County coroner.

Tindall said the avalanche site was approximately five miles into the backcountry from the highway between Hoback Junction and Alpine. The snowmobilers took off from near the confluence of Wolf Creek and the Snake River, he said.

Rescuers estimated the crown of the slide to be between 3 and 5 feet deep, Tindall said.

The location of Deadhorse Creek was not immediately clear. U.S. Forest Service maps show a Deadhorse Canyon on the north side of 9,767-foot-high Deadhorse Peak in Targhee National Forest. Those features are located above the South Fork of Indian Creek, which flows south to the Palisades Reservoir side of the range.

Working with admittedly limited information, the Bridger-Teton National Forest Avalanche Center said the slide involved only “surface snow.” The avalanche hazard forecast for the day warned of a weak layer deeper in the snowpack.

Tindall said it was “a huge area that broke,” when the avalanche began. “They were going down that draw, they were about halfway down,” he said.

Avalanche instructors warn backcountry users to venture onto suspect slopes one at a time, to carry rescue gear such as shovels and probes, and to first search for survivors before going for help.