[MCR] Rockies: Yoho

We skied in Yoho Park yesterday, on south and northeast aspects between 1300 and 2450 m. 

We found excellent boot top skiing conditions with no slab avalanche issues where we were. Bulletins are reporting a Wind Slab problem and I’m sure there are some lurking out there in some higher elevation locations but we didn’t see any in our zone.

The greatest problem I have been noticing, and it has been a trend on my tours over the past couple of weeks, is that of cornices. Every day I have been out I have noticed recent cornice falls, up to size 2. Yesterday I saw two of them that probably ran in the previous 24 hours. Although the cornices that failed were relatively small, they pushed a lot of loose snow with them and ran surprisingly far down slope, no doubt because of the weak facets and surface hoar on top of the snowpack.

I have a feeling that the big temperature swings between night and day are triggering these cornices. Yesterday we saw a swing from -28 to -6 over a few hours. So the classic “critical factors” of a rapid rise of 3 degrees in an hour, or a temperature rise into the -5 range, seem to hold. Pull your thermometer out and reduce your exposure time under cornices.

Mark Klassen

ACMG-IFMGA Mountain Guide

Banff-Lake Louise, Canada

Alpinism | » Revelstoke Long Weekend

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