Detailed Accident Report

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Date: 2010-01-06
Submitted By: JHMR
Place: Jackson Hole Mountain Resort
State: WY
Country: USA
Fatalities: 1
Summary: 1 skier buried, recovered, and died in hospital


Date of Incident: 1-6-2010

Submitted By: Jackson Hole Mountain Resort on 1-9-2010

Place: Cheyenne Bowl Shot 11, Jackson Hole Mountain Resort - Teton Village, Wyoming USA

Summary: Ski Patroller caught, carried and buried during avalanche hazard reduction efforts


This incident occurred on an avalanche hazard reduction route that has been run by ski patrollers at the Jackson Hole Mountain Resort since 1966. Snow first began to accumulate in this area in early October, however limited snowfall during the rest of the fall prevented access to this area until mid December.

The first avalanche hazard reduction efforts were conducted on this route on December 12, 2009 in historically shallow conditions. On that day explosive hand charges were deployed in the top of the Cheyenne Shot 11 starting zone with no results. Hand charges deployed in connected adjacent avalanche starting zones on both sides triggered Class 2 sized soft slab avalanches. One ran a long distance and undercut and released the lower portion of the Cheyenne Shot 11 slide path (Cheyenne Shot 11a). On the 14th this route was run again with no results in this area. On the 16th a two foot deep hard slab was triggered by a hand charge in the lower portion of the Cheyenne Shot 11 avalanche starting zone above the cliff band that separates the Cheyenne Shot 11 and shot 11a avalanche starting zones. At that time three hand charges were deployed in the upper portion of the Shot 11 starting zone with no results. On the 18th this route was run again. At this time a 30 inch hard slab was triggered from the adjacent connected slide path to the skiers left known as the Snag. On the next day a two pound air-blast was detonated in the upper portion of the Shot 11 starting zone with no results. Dry conditions prevailed until the end of December. This route was run again on the first and second day of January with no results in this area.

Accident and Rescue Summary:

On the morning of January 6, 2010 four patrollers assigned to route seven, conducted avalanche hazard reduction efforts. When they arrived at the start of the Cheyenne Bowl portion of their route they deployed a two pound hand charge, with no results, from a safe location (Rendezvous Trail) into the snag avalanche starting zone which is adjacent and connected to the Cheyenne Shot 11 avalanche starting zone. After that two patrollers dropped off of the trail and put ski cuts in the upper portion of the Shot 11 starting zone. This is a steep rocky area that had not yet been opened to the public due to low snow depths. One of these patrollers cut to the skier’s right. The other patroller assessed the snow depth and remarked that there was not a lot of snow here. He made a ski cut to the left and then to the right. This patroller then threw two hand charges below him. Right after these charges detonated a hard slab avalanche broke out 90 feet above the patroller who had deployed these charges. The second patroller was on the skier’s right flank of the avalanche crown. A third patroller was further to the right and saw the fracture propagate across the slope. The forth patroller was in a safe location on Rendezvous Trail.

At 8:31 AM one of the four patrollers on this route made a radio call that stated one of their route members had just been swept out of sight over a cliff by an avalanche. The patroller on the edge of the slide was able to cling onto a tree and avoid being swept away. He was not injured. The other two route seven patrollers were not caught by the avalanche.

A rescue was immediately initiated by the victim’s three companions. The location of the buried patroller was quickly identified with an avalanche beacon and confirmed by probing. Patrollers from adjacent routes and mountain station assisted excavation efforts. First aid, comprised of AED and CPR, was administered and the patient was packaged for transport to the medical clinic at the base of the resort. Transportation from the site began at 8:53 AM and arrival at the clinic occurred at 9:02 AM.

Avalanche Data:

The starting zone of this avalanche faces east-northeast and had a slope angle of 41 degrees. The width of the crown in the starting zone was 155 feet. The top of the avalanche crown was at an elevation of 9,500 feet. It ran 800 feet. The tow of the debris stopped at an elevation of 9,100 feet. The alpha angle of this slide was 31 degrees. The depth of the crown face was two to three feet. The flanks of the crown were up to four feet deep. The bed surface was comprised of a hard crust of well sintered faceted grains. Failure occurred in a thin layer of coarse (2 to 4 mm) faceted snow above this hard bed surface. This avalanche was classified as HS-AE-R3/D3-0 and deposited up to seven feet of debris in the deposition zone. The victim was buried 5.5 feet deep, head downhill. Photographs of this avalanche are posted on the internet in the weekly snowpack summary for the week of January 1 to 7, 2010 at

Weather and Snowpack History:

Weather stations that have been operational since the mid 1960’s exist in the immediate area of this incident. The Rendezvous Bowl (RB) snow study plot is located 740 feet to the west at an elevation of 9,580 feet. An automated wind station is located 2,300 feet to the north at an elevation of 10,300 feet. The snow study plot is equipped with automated instruments that record new snowfall, moisture, temperature and total depth in continuous 15 minute increments. This station became operational for this season on November 6, 2009. At that time there was 12 inches of settled snow on the ground at that site. Snow conditions at this site were monitored remotely on a daily basis prior to December 11th and supplemented with daily visits by avalanche specialist after that date. The wind station became operational for the season on October 27th and provides continuous wind speed, wind direction and temperature data in 15 minute increments.

On December 11th the total snow depth at the RB plot was 25 inches. A snow pit profile was conducted on that day at a location that is 560 feet away from the Cheyenne Shot 11 avalanche starting zone. This profile site was located on a northeast aspect at an elevation of 9,250 feet and was considered to be representative of conditions in this area. The snow depth at the pit location was 22 inches. The profile was comprised of 19 inches of weak depth hoar beneath three inches of new snow.

During the next six days a series of storms brought 40.5 inches of new snow with 2.6 inches of moisture (6.5 % average density) to the RB plot. Winds during this period averaged 24 miles per hour from the west-southwest (217 to 257 degrees). Temperatures at the RB plot ranged from 6 to 26 degrees during these six days. During this period this route was run on four days with results in the subject slide path and adjacent connected slide paths obtained on the 12th and 16th as discussed above. On the 19th after this storm cycle had ended an explosive air blast was detonated high in the subject starting zone with no results. The total snow depth at the RB plot on the 19th was 39 inches.

From the 18th of December to December 30th conditions were mostly dry. A trace to two inches of new snow was measured on several of these days. The total snowfall at the RB plot during this 12 day period was 9.4 inches with 0.7 inches of moisture (8 % average density). The total snow depth at the RB plot on the 30th was 36 inches.

Another storm system impacted the area during the period of December 31, 2009 through January 2, 2010. Twenty-four inches of new snow with 2.1 inches of moisture fell at the RB plot (9 % average density). Winds during this storm averaged 21 miles per hour from the southwest and decreased to 13 miles per hour and veered to the northwest near the end of this storm. Temperatures during this period ranged from 4 to 22 degrees. The total snow depth at the RB plot on the 3rd was 50 inches. This route was run on the 1st and 2nd with no results in this area.

The next storm system began with light snowfall on the morning of the 5th. Snowfall intensity increased in the afternoon and continued through the night and into the next morning. Ten inches of new snow with 1.5 inches of moisture (15% density) accumulated at the RB plot during this period. Winds were west-southwest (258 degrees) during this storm with 30 mile per hour averages and gusts to 58 miles per hour. Temperatures ranged from 15 to 21 degrees. Strong winds were drifting snow and loading lee aspects at the time of the incident. The total snow depth at the RB plot on the 6th was 56 inches.

On the morning of this incident this portion of the resort was rated to have a stability evaluation of considerable hazard. Potential sliding surfaces were identified as faceted snow and crusts. Patrol workers were advised that 10 inches of new snow with over an inch of moisture and strong west-southwest winds had loaded lee slopes. Slab avalanches, to two feet in depth or more, were to be expected. Concerns regarding the potential for crowns to occur well above their typical locations were expressed during the morning briefing. These concerns were based on the known presence of weak faceted snow at the base of the snowpack and the potential for deep hard slabs to fail on that persistent weakness.


From the Jackson Hole News & Guide:

Patroller Wolling dies</B>

By Angus M. Thuermer Jr.

January 9, 2010

Jackson Hole Mountain Resort ski patroller Mark “Big Wally” Wolling died in an Idaho Falls hospital Saturday afternoon, friends and resort officials reported.

Wolling was critically injured in an avalanche Wednesday. He had been performing avalanche hazard reduction duties before the resort opened to the public when he was caught, carried and buried under six feet of snow for about 10 minutes.

His family and a friend were at his side at the Eastern Idaho Regional Medical Center when medical workers removed him from life support and he died. Mike Fischer, a friend who had traveled to Idaho Falls to be with Wolling relayed the news to valley residents through an Internet message.

Word soon spread among workers at the resort, according to skiers there. Resort officials said they were “extremely saddened,” to confirm his death.

“Widely loved by colleagues at Jackson Hole Mountain Resort and across the ski industry, his passing leaves us with an enormous sense of loss,” resort president Jerry Blann said in a statement. “We send our thoughts and prayers to his family and friends at this tragic time.”

Wolling, 58, was a veteran of the mountain, where he worked since 1978. He was a core member of the Jackson Hole outdoor athletic community who pushed fun to its limits. He worked summers as a carpenter.

Resort officials called him “an invaluable member” of the ski patrol since 1989. “As one of the longer tenured patrollers, his experience, camaraderie, team spirit and sheer size were legendary in Jackson Hole and he will be deeply missed for a very long time,” they said in a statement.


From the Jackson Hole News & Guide:

Patroller caught in avalanche headed for Idaho hospital

By Thomas Dewell, Cara Rank and Angus M. Thuermer Jr.

January 6, 2010

The ski patroller buried in an avalanche Wednesday morning at Jackson Hole Mountain Resort was being transported to Eastern Idaho Regional Medical Center in Idaho Falls, Idaho, a spokeswoman for St. John’s Medical Center said just after noon on the day of the accident.

Mark “Big Wally” Wolling, 58, was caught in the slide at 8:26 a.m. as patrollers were reducing the avalanche hazard at the resort, the resort reported at a noon press conference. The slope was not open to the public.

Wolling’s fellow patroller found him by using a radio transceiver. He was buried under six feet of snow, dug out within about 10 minutes with no detectable pulse.

Rescuers transported him to the Teton Village Clinic by sled in a ride that took six minutes. After eight minutes of work there, medical personnel detected Wolling’s pulse, resort officials said. He was transferred to St. John’s Medical Center via ambulance and was prepared for the flight to Idaho Falls.

“Our prayers are with Mark and his family,” resort President Jerry Blann said at the news conference. “Our staff exhibited extreme professionalism.”

Jackson Hole Mountain Resort received 10 inches of snow in the 24 hours leading up to Wednesday morning and substantial amounts in the previous week. The Bridger-Teton National Forest Backcountry Avalanche Hazard & Weather Forecast – – said the avalanche hazard was high above 7,500 feet in the Teton area.

The resort offered the following account of the accident:

Members of ski patrol were conducting routine avalanche hazard reduction on the Cheyenne Bowl Route at approximately 9,350 feet. Wolling threw and exploded a hand charge from Rendezvous Trail into Cheyenne Bowl with no result.

He and his partner ski cut the area below and stopped above a cliff. Wolling threw two more hand charges. These exploded simultaneously and caused the snow to fracture above where both stood.

Wolling’s partner, whom the resort did not name, was able to grab a tree. Wolling was swept over the cliff and down the slope into the bowl.

Ski patrollers conducted cardiopulmonary resuscitation and administered an automated external defibrillator while readying for transport to the village clinic. The AED is the mechanism that did not detect a pulse and hence did not administer a shock.

The slope had not been open to the public this season. It had been visited and bombed by ski patrol earlier this winter, however.

At the time of transport to St. John’s Medical Center, Wolling was exhibiting vital signs.

St. John’s Medical Center reported at 12:35 that Wolling would be transported via fixed-wing ambulance to Idaho Falls.

Wolling has been on the patrol since 1989.

“[Wolling] is an amazing person who has been on the JHMR team since 1978, he’s definitely part of our family.” Blann said in a prepared statement.

Jackson Hole Mountain Resort is operating all lifts except for the Aerial Tram, Sublette and Thunder quad which will be closed for the remainder of the day.

“Jackson Hole Mountain Resort has established standards and protocols for minimizing the risk of avalanche that are based on the current weather and snowpack conditions,” the resort said in its statement. “Jackson Hole Mountain Resort receives over 400 inches of snow annually and is dedicated to making the skiing and riding as safe as possible for our guests. Avalanche conditions change hour-by-hour and day-by-day. JHMR Ski Patrol continuously monitors elements of the weather and snowpack conditions 24 hours a day throughout the winter and uses this information to continually assess potential hazards.”

The next resort statement on the incident was scheduled for 4 p.m. today.