- Location: St Marys Lake, Front Range
- State: Colorado
- Date: 2016/01/16
- Summary Description: 1 climber caught, buried, killed.
- Primary Activity: Climber
- Primary Travel Mode: Foot
- Location Setting: Backcountry
- Caught: 1
- Partially Buried, Non-Critical: 0
- Partially Buried, Critical: 0
- Fully Buried: 1
- Injured: 0
- Killed: 1
- Type: HS
- Trigger: Unknown
- Trigger (subcode): Unknown
- Size - Relative to Path: R3
- Size - Destructive Force: D2.5
- Sliding Surface: O - Within Old Snow
- Slope Aspect: E
- Site Elevation: 11200 ft
- Slope Angle: --
- Slope Characteristic: Planar Slope
This was a hard slab avalanche, the trigger is unknown, medium size relative to what the path could produce, large enough to bury or kill a person, and broke into old snow layers (HS-U-R3D2.5-O). At the top of the path, the avalanche initially broke below freshly wind-drifted snow. It quickly stepped down into deeper persistent weak layers near the ground. CAIC forecasters estimate the avalanche was three to four feet deep at the crown face, about 1,000 feet wide, and ran approximately 500 vertical feet into the lake. The impact moved large, three-foot thick ice blocks across the lake surface.
The accident occurred near the beginning of a powerful winter storm. It was the second storm to affect the Front Range in January. At Winter Park Ski Area, 7.5 miles to the west-northwest, snowfall began on January 15. By the morning of January 16, the Winter Park Ski Patrol reported 13.5 inches of new snow. In the week prior to the accident, they measured 17.5 inches of new snow with 0.8 inches of snow water equivalent. The Berthoud Pass SNOTEL site, 7.6 miles to the west-southwest also measured 0.8 inches of snow water equivalent in the week prior to the accident. You can view a graph from the Berthoud Summit SNOTEL site here.
This was a very windy period across the Front Range. At the Berthoud Pass METAR site, 12,490 feet, 6.7 miles to the west-southwest of the avalanche accident, the hourly average wind speed only dropped below 20 miles per hour for five hours, in the five days prior to the accident. At the CAIC weather station on Berthoud Pass, 11,861 feet, 7.6 miles to the west-southwest of the accident, north and west winds averaged 16 miles per hour for the week prior to the accident with gusts as high as 58 miles per hour. You can view a graph from the Berthoud Pass METAR site here. You can view a graph from the CAIC Berthoud Pass station here.
In the Front Range, early season snow developed into well-formed depth hoar at the ground. Periods of clear, cold weather interspersed with stormy periods in December and early January formed layers of near-surface faceted crystals. Wind events drifted hard, cohesive layers of snow over these weak layers forming a complexly layered snowpack.
Due to dangerous avalanche conditions, CAIC forecasters were unable to assess the snowpack at the crown of the avalanche. They conducted a snow profile on a safe, nearby, slope with similar aspect and elevation. The profile was 185 centimeters deep, deeper than the estimated crown depth.
There was a 10 cm thick layer of (4-Finger hard) depth hoar at the bottom of the profile. In late December and early January, most snowpack tests in the Front Range zone indicated strengthening and sintering of the basal depth hoar layer. However, observers continued to find areas where the depth hoar remained weak and reactive in snowpack tests. The middle 130 cm of the snowpack consisted of three layers of soft (Fist hard) near-surface faceted crystals interspersed between very firm (Pencil hard) layers. Layers of wind drifted and recent storm snow made up the top 50 cm of the snowpack.
Events Leading to the Avalanche
The climber arrived at the St Marys trailhead around mid-day Saturday, January 16, 2016. A powerful winter storm had begun the day prior. Friends and family reported that the climber often visited the area in the winter. His usual route was up and down the access road, and he usually ascended a gully to south side of the lake (climber’s left) for exercise.
It is unknown exactly where the climber was at the time of the avalanche.
The climber was found buried at the lake margin below a steep slope. Avalanche debris spread several hundred feet over the lake ice. Large chunks of ice were broken out and encased in avalanche debris.
Friends reported the climber missing the evening of January 16, 2016, when he failed to return for dinner. The Clear Creek County Sheriff's office initiated search and rescue efforts that evening. Weather prevented a safe search, and the rescue team aborted their attempt that night.
The Alpine Rescue Team returned on Sunday, January 17, 2016, and again faced poor weather conditions. Windy conditions made it difficult for the search dogs to work. On Monday January 18, the weather was clear but the winds were still quite strong. SAR teams searched a wide area around the lake and continued organized probe lines across the avalanche debris. Rescuers were concerned about the danger posed by the snow that remained on the slopes above the lake.
A large search effort began on Saturday January 23, 2016, with probe teams and avalanche search dogs. The searchers concentrated on the avalanche debris across the lake ice. An avalanche search dog found the climber at 8:30 AM.
The stormy weather on January 16 made backcountry travel difficult. This meant the route the climber took and the avalanche went unwitnessed. The storm from January 15 to 21 increased the avalanche danger and made search conditions hazardous. The climber was not wearing an avalanche transceiver or RECCO reflector. While a transceiver or RECCO reflector would not have changed the outcome of the avalanche, they may have significantly shortened the search time.
Thanks to the Clear Creek County Sheriff’s Department, Alpine Search and Rescue, and Dale Atkins for their assistance in compiling this report.
Figure 17: Snow profile observed on 1/18/2016, from near the south flank of the St Marys Lake avalanche accident. See Figure 1 for site location.