Conditions will be tricky to manage this weekend, as a touchy surface hoar layer is buried only on some slopes and not others. Make constant snowpack assessments as you travel and take a cautious approach to terrain selection.
Confidence
Fair - Due to variable snowpack conditions
Weather Forecast
Saturday: Light W wind. Alpine temperature near -14. No snow.Sunday: Light N wind. Alpine temperature near -15. No snow.Monday: Light NW wind. Alpine temperature near -8. Light snow.
Avalanche Summary
A natural cycle of size 1-3 storm slabs occurred over the last few days. Skiers also several avalanches up to size 2, failing on buried surface hoar or facets. We are now moving into a period when natural activity is likely to decrease, but human-triggering will remain a concern.
Snowpack Summary
50-90 cm of recent snow is settling into slabs above old snow surfaces including surface hoar (found especially at and below treeline in sheltered areas), a sun crust (on steep S to SW-facing slopes) and facets. The distribution of buried surface hoar is patchy, but where it does exist, it is touchy, with widespread propagation and remote-triggering occurring. Recent winds have left wind slabs in the lee of terrain breaks such as ridges and ribs at alpine and treeline elevations. In areas sheltered from the wind, fast-moving sluff could throw you off your feet or carry you into a terrain trap. A strong mid-pack overlies a weak facet/crust layer near the base of the snowpack, which is now considered inactive.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.