Confidence
Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period
Weather Forecast
Friday: Ridgetop winds back off to mod/strong southerlies. Treeline temp -8. Occasional Flurries. Freezing Level at valley bottom.Friday Night: 10 - 20 cm overnight.Saturday: Southerly ridgetop winds initially light becoming strong late in the day. Treeline temp -5. Light snow. Freezing Level at valley bottom.Sunday: Light SW winds at ridgetop. Treeline temp -5. Lingering flurries. Freezing Level at valley bottom.
Avalanche Summary
Monday's moderate southerly winds drove soft slab formation near ridgetop. Several small wind slab avalanches were reported. There are still a few reports of fast moving loose snow avalanches coming in too.
Snowpack Summary
More than 120 cm of snow has accumulated this week in some areas. Various storm snow instabilities have been observed. Southerly winds picked up a bit Wednesday evening and created new wind slabs and touchy cornices near ridgetop. The raucous sluffing is likely a thing of the past but still something to keep in mind below treeline, especailly near terrain traps. The mid-pack is reported to be settling well. The late November surface hoar, down 100-160 cm (between 1500 and 2000 m), is producing moderate to no results in snowpack tests, with isolated sudden results. The early November crust, near the base of the snowpack, has produced occasional sudden results in snowpack tests. Professionals are still cautious about these lingering persistent slab problems, but the likelihood of triggering is low. Be wary of steep complex terrain with a shallow snowpack, where triggering a persistent weakness is more likely.
Problems
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.