The huge avalanches this week have been a reminder that, deep in our snowpack, lives the Dec 1 layer. It will take a large trigger to get it moving, but that can be done with cornices, slabs, etc.
A conservative frame of mind is good this winter.
Moderate to strong winds on Sunday formed wind slab in the Alpine and down into treeline. These slabs may have buried surface hoar or a preserved stellar layer and could be sensitive to human triggering.
Several persistent weak layers (see snowpack summary) in the upper 1m have been recently active, and in some instances, have stepped down to the deeper Dec 1 crust/facet layer. Investigate the snowpack before committing to your line.
The Dec 1 crust/facet combo woke up this past week, spitting out very large avalanches and knocking out mature timber in skiable terrain. This crust lives between 1700-2300m throughout the park, and will need a large trigger (cornice, slab, etc).
Fairly benign weather the next few days, with another alpine inversion slated to arrive Thurs
Tonight: cloudy, Alp low -8*C, light winds
Tues: cloudy, Alp high -7*C, light winds
Wed: sun and cloud, Alp high -8*C, light W winds
Thurs: sun and cloud, Alp high -2*C with temp inversion in valleys, light SW winds
Up to 35cm of recent snow now buries the Jan 20th (2-4mm) surface hoar. The Jan 11 (2-5mm) surface hoar is down ~70-90cm. The Dec 1 crust/facet combo is down ~1.5 - 2.5m. Widespread wind affect at treeline and above with pockets of wind slab.
Limited avy activity observed Monday. Control work on Sunday produced results up to sz 3, one of which stepped down to the Dec 1st layer. Skiers were triggering small wind slabs up to size 1.5 on steep rolls.
Avy Control on Saturday, just West of the Park produced several sz 4 - 4.5 avalanches, extending historical trim lines through mature timber.
