Miller Ck - AST 1 Class Obs

Riding quality was:

OK

Snow conditions were:

• Wind affected

We rode:

• Mellow slopes
• Open trees

We stayed away from:

• Convex slopes
• Steep slopes

The day was:

• Cold
• Sunny

Avalanche conditions

• Slab avalanches today or yesterday.
• 30cm + of new snow, or significant drifting, or rain in the last 48 hours.
• Whumpfing or drum-like sounds or shooting cracks.

Tour from HBM skihill to Lower Miller Ck for an AST 1 class. Nice day afterthe recent storm with light NW winds, -9c and sunny sky. Moderate ridgetop winds were noted with some wind transport, with minimal snow left to transport. Up to 50 cm of storm snow fell during the storm, which started cold, and went out warm. This was quickly reditributed but a major cold front wind event on Saturday afternoon with wind gusts reported upwards of 80km/h. Alpine and upper treeline areas are now heavily wind affected with suspect hardslabs on South through East start zones. It appears there was a fairly widespread cycle throughout the region in the storm snow on friday night, and wind slabs in the Saturday PM event, up to Size 3. We saw several slab avalanches out in the Miller Ck basin on very steep, windloaded southeast aspect alpine slopes, and a few in moderate terrain as well. Crown depth was hard to tell after being blown in, but a few of these appeared to step down and scrub to ground. We dug a quick snow observation pit at treeline in a relatively sheltered area, with an average depth of 110cm. Upper 40 cm is recent storm snow. Of note, the lower snowpack, from 50cm to ground is heavily facetted, with a few thin raincrusts laminated. This layer gave a hard, drop fracture character in an isolated compression test. This layer is throughout the region as described now in several recent MIN reports from Hankin, and Silverking Basin, and grew during the clear cold spell and shallow snowpack of early December.