We spent April 1 -3 skiing in the Healy Pass area near Sunshine Village with the Mountain Skills Semester group. In general, conditions were quite good, with temperatures between -8 and -2, light to moderate SW winds and sunny conditions with 10cm of snow falling overnight on Sunday night. We saw little in the way of avalanche activity except for a few size 1 loose snow avalanches on NE aspects triggered by wind loading and one size 2 slab on a SW aspect triggered in the recent storm snow by solar warming. However…..we we're a bit surprised by the following occurrence….
While skinning up after skiing a low angled run on the edge of a west facing bowl below Monarch Peak, we experience a very large settlement while we were standing grouped together. When we regained the ridge at the top of the bowl we saw that a shooting crack had propagated 200m across the upper part of the bowl, but had not turned into an avalanche, as the bowl was not steep enough to slide. We initiated this shooting crack from over 200m away!!! The failure plane for this fracture was the Feb 14 surface hoar layer, and the shooting crack started from a thin snow pack area (height of snow 125cm). About 10m away from this spot, the height of snow was 225cm. Snow tests in this shallow spot showed an easy, clean shear, 70cm deep, with a lot of potential for propagating over a large distance.
So what does this mean? It is still very possible to trigger a large, destructive avalanche on the Feb 14 surface hoar layer from a shallow (windward) snowpack area.
Jason Billing - Alpine Guide/Assistant Ski Guide Grant Meekins - Mountain Guide Yamnuska Mountain Adventures
 The shooting crack extends across the entire slope seen in this photo. |