Local Avalanche Incidents

March 30th, 2015 - Chilkat/Haines Pass (West Side), St. Elias Range, B.C., Canada

Location:Chilkat/Haines Pass (West Side), St. Elias Range, 59.615 N, -136.486 W
Date/Time of Occurrence: 3/30/2015
Mode of Travel: A/T skis and skins
Accident Type: Partial Burial
Number in Party: 2
Persons Buried: 1 (partial)
Persons Injured: 0
Persons Killed: 0
Accident Details:
Type: Soft slab
Trigger: Artificial - skier triggered, unintentional
Size: D2, R4
Sliding Surface:New/old snow interface, released on a buried surface hoar layer
Aspect: NW
Elevation: 1440m
Slope Angle: approx. 30-degrees
Depth: 30cm average, deeper in areas

Weather Summary:
From March 25th-30th about 30cm of new snow fell above 2500ft, with gusty south winds. March 21st brought around 30cm of new snow over the mountains, with snow levels near 2000ft and moderate south winds. March 12th-13th brought 60-90cm of new snow over the mountains. Winds were strong and variable.

The most recent (though expired) advisory published by the AAIC for Haines on the day of the incident rated the danger as CONSIDERABLE, stating:

  • In areas that are wind loaded by recent south winds, human triggered avalanches are likely on density interfaces within the new snow. Be wary of north aspects below ridgelines, and gullies which may be cross-loaded.

  • The surface hoar layer that formed on March 23rd had just been buried, though reports of its presence had not yet come in to the avalanche center. Not until the weather cleared on the 30th did several reports of human-triggered avalanches on the surface hoar layer come in.

    Details of the Incident:

    It was a very busy day at the pass, being the first clear day after a week of storms. The party of two skiers scoped out multiple areas to ski that day, including Mineral mountain area and the north slopes of Glave peak, both of which were busy with high-marking snowmachiners. The two were generally expecting unstable avalanche conditions that day, and were surprised at some of the slopes that snowmachines were on. They elected to skin up the gentle hills to the west of the highway, across from Three Guardsmen Lake.

    The two dug a snowpit on a 20-degree E aspect just above the highway at 1000m. They found "weird facets, then all sorts of storm layers above." A compression test failed on CT11 in the top 10cm of new snow. As they kept tapping the column, multiple layers failed in sequence down to 50cm. They did an extended column test, and found no propagation of the failures (ECTN). The two deemed it unsafe to proceed onto steeper slopes on this aspect, so they kept exploring around the hills to a more northerly aspect.

    They found that shaded areas had 6-8in of powder. Hand pits as they travelled showed a hoar frost or other weak layer at the new/old snow interface. Conditions were decidedly sketchy, so they elected to go up a mellow ridge and look around. The two skiers skirted north to a seemingly mellow ridge (approx. 30-degrees), spaced out along the skin track. As the first skier climbed, the slab broke about 10m above him with a whumph. 15-25cm deep debris pulled his skis out from under him, and he was swept about 30m down the slope. The crown ran 100m down into a steep rollover on an adjacent slope, where the it was deeper and the debris pile a lot larger. Total crown width was around 150m; the slide ran about 50m vertically.

    As Skier 1 fell over onto his right side, he was buried in debris. His legs were buried about 90cm deep, with his back 75cm deep. His head was sticking out of the surface, as were his hands. He tried to dig himself out, but the debris was set up too solidly. He estimates that had a partner not been there, it could have taken hours to dig himself out. Luckily, Skier 2 was far enough behind to not be caught in the slide, and was there quickly to help dig out Skier 1 (first, the two had a quick chat about whether it was safe for skier 2 to proceed). The two were shaken and surprised, but there were no injuries.

    These two skiers were right to be cautious about the conditions, going out after a week of snowfall. The surface hoar layer was not yet on anyone's radar, but these two immediately identified a very sensitive weak layer below the new snow, and adjusted their plans accordingly. Their decision to proceed up a small 30-degree ridge in a low-consequence area is one that many skiers in the situation may have agreed with. In this case however, the surface hoar layer was touchy enough to pose a danger even on otherwise mellow slopes. It was a good thing the second skier was spaced farther back.

    In retrospect, Skier 1 said: "I had concerns about stability...my main mistake was thinking that the ridge was not a problem. It didn't seem steep enough to really pose a danger to us. I accepted that there was danger that day, but my level of tolerance was a little too high for those conditions."