CSAC Avalanche Incident


Sun Valley, Idaho - February 22, 1998

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Official Reports

MORMON HILLS AVALANCHE FATALITY, FEBRUARY 22, 1998

Carey, Idahobr Prepared by Janet Kellam, Sun Valley Avalanche Center February 24, 1998

SYNOPSIS:On Sunday, February 22, 1998 aprx 28 miles north of Carey, Idaho, in the southern end of the Pioneer Mtn. range, a 42 year old man snowmobiling with friends triggered, was caught and killed by an avalanche while high marking on a slope. The party was using avalanche beacons but the victim showed no signs of life when recovered aprx 20 minutes to an hour after the avalanche occurred.

REPORT: The afternoon of February 22nd, a group of snowmobilers was traveling from the end of the plowed Little Wood Reservoir road into the southern end of the Pioneer Mtn. range. This trailhead was 20 miles up a backcountry road from the town of Carey. They then traveled by snowmachine up the now unplowed road bed and appear to have taken at least one side trip up onto the neighboring ridgelines before dropping back down to continue up the summer road. Next they traveled further up the road and sloping terrain to reach an area that climbed more steeply to the open ridgeline at aprx. 8400ft. This area consisted of two pronounced open bowls or faces that were joined at the top, but separated in the middle by a more gently sloping, treed ridgeline. This area was approximately 8 miles from the trailhead.

The group had been high marking in this area when Ron Berry, the victim, became stuck just above the center ridge, on a 30-35 degree angle slope. Berry climbed off of his sled and was trying to dislodge it when Craig Hanson rode up to assist him. Hanson was apparently almost to Berry when the slide fractured above them. A third member of the party said that he had been down below and just beginning to head up when he saw the avalanche break loose. He immediately turned and rode over the bench behind him and down to several other members of their party who had been stuck below. Apparently another member of the group, Hanson's wife Lita, was carried along the edge of the slide in the more easterly bowl but drove out and down to alert the other members, then continued out to alert authorities. Hanson turned and was driving down and out of the slide when he was knocked from his sled and tumbled in the debris. He came to a stop, partially buried. (aprx 8000ft elevation) From witness reports he had either ended up along the lower angle center ridge or fairly high upslope in the debris on either side of the ridge.

Berry had been carried down into the more westerly bowl, out of sight. The riders had been wearing beacons and carrying shovels but no probes. It is not certain how many did have beacons. Reports vary as to the exact time of burial and recovery time. Burial time is estimated to be between 3:00 and 4:00pm. Recovery time has been noted as anywhere from 20 minutes to an hour. The snowmobile was located first, by digging where the beacon signal was strongest and Berry was located shortly thereafter. Berry was in a vertical position just uphill from his sled which had come to rest against a 1 foot diameter fir tree. Burial depth is estimated at 4 to 6 ft. deep. It is not known if this is his head or average depth as he was in a vertical position. All of the debris had converged in a gully or crease at the bottom of the slope as it entered the lower angle trees. The debris formed a relatively narrow "toe" or moraine due to the terrain and was estimated to be up to 30 ft deep at the downhill edge. Berry was located approximately 30-40ft into the debris where it first entered the trees. This west bowl section of slide was estimated to have a 60 yard crown face, 26 to 32" deep, 100yds long to the debris, and the debris 70 ft wide by 75 feet long.

Reports indicate that the more easterly bowl or face had been only a narrow slide initially but there is some confusion as to this. Additional portions of the slope may have released up to an hour later. Sun Valley Heli Ski guides and pilot describe the avalanche site as appearing similar that afternoon to the drawing that was produced from the investigative visit the following day.

The call for outside help was received shortly after 4:oopm. Sun Valley Heli-Ski was immediately placed on standby to receive authorization to transport search and rescue personnel and an area avalanche dog. The helicopter received authorization shortly thereafter and flew out to locate the accident site, not knowing any status on the victim or recovery. When the SVHS helicopter arrived, the victim had been recovered by the snowmobile group and placed on a sled, presumed dead. Lifeflight was inbound and radioed to the ground party to begin CPR. This was begun by the heli-ski and nordic patrol group until Lifeflight's arrival whereupon the victim changed hands. By then it was beginning to get dark and all parties hurriedly packed up and departed the scene. The victim was flown to Hailey airport and transferred to adjacent Wood River Medical Center.

Monday afternoon, the following day, Rick Barker and Janet Kellam of Sun Valley Avalanche Center were able to snowmobile to the accident site with Victor Thomas of Blaine County Search and Rescue, a local sheriff and a friend of the victim who had not been on the Sunday ride. Then, a more complete snow assessment and site study was performed, although again within a limited time frame.

CONTRIBUTORY FACTORS

Terrain:

Slope Angle : Bed surface slope angles varied from an angle of 38 degrees to 25 degrees. The slope angle was 38 degrees approximately 20 to 30 feet above the victims location where he and his machine were stuck. This was also the highest elevation point of the crown face. The crown face that extended above the westerly bowl turned into a bed surface slope angle of 25 degrees aprx. 40 to 50 feet to the west of the high point of the release and along a large portion of the top of the westerly bowl release. Beneath this fairly low angle section along the top of the slide path, the slope steepened in the center of the bowl to a 35 degree slope angle. The crown face and bed surface of the more easterly avalanche appeared to have slope angles of predominately 30 to 35 degrees. The slope angle decreased directly beneath the victim as the center ridge fanned out between the two bowls. However, the westerly bowl sloped away from the center ridge and began a steady increase in steepness to reach 34 to 35 degree slope angles above the center of the deposition. Several areas of the avalanche path that were aprx 25 degrees were very apparent by the presence of broken slabs and debris that had slid only a short distance. The slope angle then rapidly flattened at the base of the bowl as the slope narrowed into a gully and entered the trees. This accounts for the moraine-like shape of the debris and the very deep deposition. Although a very small area along the crown was a 38 degree slope angle, the bulk of the slope itself was a 30 to 35 degree slope angle.

Aspect: The two faces and the dividing sub ridge had a North to Northeasterly aspect. The top of the slope was a fairly prominent terrain feature. There were signs of snow having been transported by southerly winds across the ridgeline and onto the north facing slopes.

Shape: The more easterly (actually south easterly) face was not as sharply bowl shaped but was bordered on each side by more gently sloping ridges. The two avalanche bowls shared a center lower angle ridgeline that began 30 or 40 feet below where the victim and his sled had been stuck. This ridgeline had not slid. The easterly avalanche slope dropped into a depression with a small bench on the downhill side, before the slope again dropped off to the summer road bed. Debris was piled up in the depression an estimated 30 feet deep. The riders had accessed the slopes by climbing up to this bench, then high marking from here.

The westerly bowl that the victim slid into was a very cupped bowl shape that became steeper mid slope. As you approached the bottom a much lower slope angle created a rapid terrain transition at the base of the bowl where it entered a fairly dense stand of conifer trees. This created a flatter, narrow gully and accounts for the debris turning into a deep tongue of snow with smaller side bulges as you entered the trees.

Weather:

Sunday, Feb. 22nd was one of those "perfect" days. At the Sun Valley Forecast Center the day dawned sunny and clear. Records from the Garfield SNOTEL station near the accident site indicate there may have been some lingering morning snow showers in the southern foothills of the Pioneer Mtns. Saturday's storm had broken and the tail end of the storm had deposited a beautiful layer of light fluffy powder snow. Seemingly "perfect" conditions for weekend skiers, snowboarders, snowshoers and snowmobilers.

Precipitation (amount/rate): Saturday's storm had dropped an average of an inch of water in thirty hours. Ketchum Ranger District recorded .72" of water that was measured as 11" of snow. Hyndman SNOTEL station at 7440 feet elevation in the eastern Pioneer Mtns. reported 1.2" of water. The Garfield Ranger station SNOTEL site at 6548 feet, and within several miles of the accident location, showed one inch of snow water equivalent deposited in the 24 hours prior to the accident. This was estimated to be between 10 to 12 inches of new snow. The bulk of the precipitation in the Ketchum area occurred between 12 and 6pm on Saturday. This was a rapid rate of loading, which lead to a more unstable snowpack for a day or two after the storm.

Wind: Powerful winds were recorded throughout the storm. Instruments on Titus Peak (near Galena Summit) recorded gusts of up to 57mph from the SW to SE and winds that gusted from 20 to 57mph for 31hours. (Friday evening into early Sunday morning.) Observers throughout the Wood River Valley noted that winds were very strong and blizzard like throughout Saturday afternoon. This type of wind probably transported significant amounts of snow and lead to an increased avalanche hazard throughout the area.

Temperature: Saturday's storm came in cool, became warm and moist, then exited with cooler temperatures. This created denser slabs that rested on weaker snow. The surface snow was deceptively light and fluffy. Garfield RS SNOTEL site at 6548 ft elevation showed temperatures the 22nd to be 8 degrees Fahrenheit at 6am, 29 degrees at 12pm, 14 degrees at 6pm. Temperatures would have been slightly cooler at the accident site at 8000ft elevation.

Snowpack:

Snow History 97-98: Up to this point, the 1997-98 winter had not had a very stable snowpack. The Sun Valley Avalanche Center daily advisory had repeatedly discussed the weak nature of the snowpack due to a shallow total snow depth early season, buried surface hoar, and sequential snowstorms that created dense slabs on top of weak layers. We had reported numerous skier, snowboarder and snowmobiler triggered avalanches throughout January and February and warned of this being a continuing possibility. The Center had emphasized the higher hazard in the southern portion of the Wood River Valley due to a shallower snowpack there this season.

Snow Structure: Upon visiting the accident site, avalanche forecasters found that the slab released 26" to 32" deep. The slab consisted of approximately 8-10 inches of now two day old snow and 16-24" of consolidated snow that ranged from four finger density to nearly one finger density. We feel that the new snow had settled from it's original depth of 10 to 12 inches because we had observed dramatic settlement of new snow depths in the Ketchum area. The slope that avalanched may have had some light wind transport from the ridgeline onto it's north face, but we really did not see as much as wind transport as might have been anticipated. However, slab depths ranged from 32" at the crown to 16" mid slope, indicating light to moderate windloading from the last four storms. Surrounding ridgelines that were visible during the trip into the site did show significant cornice development and wind deposits.

The weak layer beneath the avalanche slab was a well defined layer of flattened surface hoar crystals that were up to 12mm in length up at the crown face. The bed surface was a one finger slab 8" deep at the crown and up to 20" deep mid slope. Beneath the bed surface was aprx. 6" of well developed faceted crystals and depth hoar. This depth hoar was moist mid slope, but very dry and up to 12mm long columns of 4mm crystals in the starting zone. The presence of columns indicates an earlier shallow cold and weak snowpack in this area. We received reports that several sleds were stuck down below and that walking through the snow was a very difficult wading process. This indicates that the sleds were sinking deep into the snowpack and may have been more likely to shock and stress the snow slab just above the weak layer.

Snow History this area during previous years: Local riders told forecasters that in many different winters they would ride this slope and cut loose avalanches while traversing or high marking, but nothing this big. A lone 8-12" diameter, mangled pine tree sits on the bench at the base of the easterly face, bent at a 45 degree angle downhill, suggesting previous avalanches in this location.

Other Clues to Instability: Driving up the access road on Monday, we observed natural slab releases that had run since the end of the storm. One was from a north east facing cornice release that triggered a wind roll on a slope, another was a north to northeast facing bowl (aprx 6-6500 feet elev, class 3 in size) that ran beneath the ridgeline and appeared to propagate several connected slopes in the bowl. On the snow machine ride in, we observed a similar N/NE facing bowl with several connected slab avalanches on it's face. Class 3 size.

It appeared that the group had ridden off the road and up a ridgeline before returning to the road bed a mile or two from the accident site. A long, connected avalanche had released just below their tracks on a N/NE facing slope that dropped to a creek bed beneath the ridgeline. It is not known whether the group noticed this activity. This avalanche was apparent from the slopes that climbed up to the accident site.

A member of the riding party said that he had not noticed any collapsing just before the fatal avalanche had occurred, but that they did notice the snow collapsing and cracking around them as they hiked through unbroken snow while evacuating the victim's body from the debris and out to an open area.

If they were not looking for any avalanche activity and very focused their machines and the trail, it might have been possible to overlook this apparent avalanche activity.

Human Variables:

This particular group of riders was know for achieving the more aggressive rides in the area. Earlier in January, they had triggered and outrun several large avalanches in the Baker Creek area north of Ketchum and had decided to begin carrying avalanche beacons and shovels after that experience. These riders were very skilled and knew the mountains and terrain very well. However. Their avalanche evaluation skills did not match their riding ability. The day of the fatality was a day of considerable avalanche hazard. It is not known if any members of the party had obtained the avalanche advisory for that day. Sunday had been a great day for being out in the mountains. Perfect sun, perfect powder. If they had noticed some of the avalanche releases, their ability to ride around without a problem may have given them a false sense of confidence to try highmarking in this area.

Equipment/Resources: The group did have beacons and shovels, but no probes. A set of probes may have enabled a quicker recovery time of the victim. At this point it is not known if he died from trauma or asphyxiation. He did go for a relatively short and unobstructed ride before coming to rest. The group responded quickly to locate the victim as well as to alert outside help. A significant time factor was the remoteness of the site. It is not known if they carried any first aid equipment or attempted CPR once the victim was extricated from the debris.

Comments:

This fatality was a very sobering experience for this accomplished group of snowmobile riders. It appears that this group had begun to think about avalanche safety. Sunday they had definitely been pushing the limits by highmarking in recognizable and known avalanche terrain, the day after a significant storm and during a time of considerable avalanche hazard. If they had traveled in the same manner several days after the storm, they may or may not have experienced the same result due to the the stabilization process of the newer snow and the unpredictable nature of buried depth hoar.

Several members of the party were on the slope at the same time and this could have stressed the slope enough to trigger the avalanche. One rider was able to ride off the edge of the avalanche, another was caught but only partially buried. The third person in the slide, the victim, was carried into a serious terrain trap at the base of the slope. General rules for traveling in avalanche terrain are to expose only one member of a party at a time to suspected avalanche hazard, and to avoid areas of terrain traps where debris can result in deep, destructive burials. The sequence of events and details of this avalanche fatality are all too similar to other fatalities the past several years. The facts from recent avalanche fatalities all point to the need for winter recreational travelers to pursue avalanche education and skills if they plan on venturing into avalanche terrain.

Sun Valley Avalanche Bulletin, Feb 23

Good Morning, this is Janet Kellam with the Forest Service Sun Valley Avalanche Center with the Backcountry Avalanche Advisory and Weather Forecast for Monday February 23rd 1998 at 7a.m.

Today I am afraid that I have to begin this advisory with the report of a tragic accident. Yesterday afternoon in the Mormon Hills area of the Little Wood River drainage two snowmobilers triggered an avalanche on a Northeast facing slope. One rider was buried and killed. Our condolences go out to family and friends.

GALLATIN NATIONAL FOREST AVALANCHE ADVISORY, FEB 25

Good morning, this is Karl Birkeland with your Gallatin National Forest Avalanche Advisory issued on Wednesday, February 25th at 7:30 AM.

Yesterday we received the unfortunate news of another avalanche fatality. Two snowmobilers were high-marking a slope near Sun Valley, Idaho. In an all-too-familiar scenario, the first person up the slope got stuck. While he was trying to get his sled unstuck, his partner came up to help and they triggered an avalanche. The person on the moving sled was able to ride off the slide, but the stuck rider was caught, buried deeply, and killed. This accident serves as an unhappy reminder that you should never expose more than one person to the avalanche danger at a time - putting two people on a slope greatly increases the stress on that slope and could result in more than one person being caught.

Media Reports

Carey man dies in avalanche

By ALYSON WILSON - Express Staff Writer

A snowmobiler died after being swept down the east side of Mormon Hill by an avalanche Sunday afternoon.

Ronald Lee Berry, 42, of Carey had been driving his snow machine around the remote area, 25 miles north of Carey, with six friends, said Blaine County Sheriff Walt Femling.

Berry’s snowmobile became stuck, and he climbed off, apparently trying to dislodge his machine, witnesses reported to the sheriff’s office.

Also on a snowmobile, Craig Hanson, was on his way toward Berry to assist.

A massive fracture of heavy snow broke immediately above Berry, causing the avalanche, according to reports. Hanson was closer to the edge, and started driving out, but Berry was totally surrounded by the sliding snow.

"Almost the whole hillside gave way," said Femling.

Hanson was knocked off his snowmobile but popped up before the snow settled, dense as cement. Berry had disappeared, completely covered under six feet of snow.

A portion of the hillside near another friend, Lita Hanson, also slid but she was able to drive out of harm’s way to inform four other riders, who were close.

She next drove out of the area to notify authorities of the avalanche. The call went in to the sheriff’s office at about 4 p.m.

The five snowmobilers wore PiEPS transceivers and were able to locate Berry to uncover his head within the 20 minutes it took for outside help to arrive.

The friends found Berry positioned upright and unconscious, said Femling.

First to the scene was a Sun Valley Heli-Ski guides helicopter authorized by the sheriff’s department to fly search and rescue personnel and a trained avalanche search dog to the site.

A Life Flight helicopter arrived moments after the first. It transported Berry to Friedman Memorial Airport for medical treatment at Wood River Medical Center in Hailey.

By that time, Berry was declared dead due to trauma related to the accident, said Blaine County Coroner Russ Mikel, who was not yet able to report a more specific cause of death.

Blaine County Search and Rescue, the Blaine County Sheriff’s deputies, Wood River Ambulance and Carey Quick Response Unit also responded.

Automobile access was impossible, however, on the snowy backcountry road.

"They were back there, let me tell you," said Femling. His deputies were only able to come within a two- to three-mile range of the fracture, a total of more than 50 miles from their offices.

On Monday morning, a team was sent out to profile the scene more thoroughly than was possible the evening of the accident.

They determined the slide was 75 yards long and equally as wide, said Blaine County Sheriff Lt. Greg Sage.

Snow to a depth of two feet broke loose, piling up to 30 feet in places, he said.

Avalanche danger in the surrounding area is still quite high and would-be visitors should stay out.

"You have to be prepared to rescue yourself in situations like this," he said. "With the weight of the snow, and so on, it’s tough to survive these types of incidents."

Those venturing into the backcountry need to carry both transceivers, like a PiEPS, and shovels, Lt. Sage said.

A service for Berry will be held at 2 p.m. Friday at the Carey LDS chapel. Burial will be in Carey Cemetery.

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