I spent this past weekend in Rogers Pass finishing the second part of an AST-2 class. We had a great time, spending Saturday in the Ursus Trees area and Sunday up the Illicilliwaet drainage.
Sure enough the surface hoar problems discussed in the Parks avalanche bulletins were easy to find and very reactive especially below 1850 m on shaded aspects with slabs of 75 cm+ overlying large, faceted surface hoar feathers 15 mm and larger. Dig down a bit to admire them, they can’t be missed!
Natural activity on Sunday was from the sun though, and during the warm-up there was lots of action at alpine elevations to size 3, see photo of several below Avalanche Mountain (38+ degrees, S & SW aspect, around 2400 m).
We were conservative with our terrain selection, sticking to lower angled terrain and giving avalanche paths healthy respect. But things have continued to heat up since yesterday and the hazard is now being rated High at treeline and alpine elevations, which certainly matches with my limited observations in Bostock, Connaught and Illicilliwaet drainages this weekend.
Here’s a photo of the cracking/shearing that occurred over a small convex roll yesterday to give you a bit of an idea of what would likely happen if you stepped onto something larger. We also had several huge whumpfs that sent shooting cracks for hundreds of meters.
Ski quality has been excellent, which further validates the Special Avalanche Warning that Avalanche Canada has put out — the great skiing will surely tempt skiers to be less conservative than warranted during this high hazard period of the winter. All in all, an excellent time for AST courses!