Weather Forecast
A ridge of high pressure will continue to dominate the region bringing dry conditions for the forecast period. An inversion is likely on Monday with valley cloud, clear skies above and alpine temperatures hovering at about 0.0. On Tuesday and Wednesday expect increasing high cloud and freezing levels at about 1400m. Winds should remain light out of the west/northwest for the forecast period. No significant precipitation is expected for at least a week.
Avalanche Summary
Continued point releases to size 1.5 occurred on Friday and Saturday in response to warming on steep, sun-exposed slopes. The last reported deep release on basal facets was on Thursday in the south of the region where a snow cat was working on ridge and remotely triggered a size 3 avalanche from 30m away. The avalanche occurred on a southeast facing slope at 2160m.
Snowpack Summary
Roughly 90cm of well settled storm snow exists as a stubborn wind slab in many exposed areas. With recent warming, steep, sun exposed slopes have seen a daily melt-freeze cycle while surface hoar has been growing in some shaded terrain. Below the recently formed storm slab you may find surface hoar buried around January 8th. This interface seems to have become less of a concern for most operations, and is showing mainly moderate to hard resistant planar results in snowpack tests.There are 2 other layers of note which professionals are keeping a close eye on: The late-November persistent weak layer consists of a sun crust on steep south facing slopes and surface hoar in sheltered areas and may sit well over 200cm below the surface. At the base of the snowpack you may also find the October persistent weak layer which consists of facets sitting on a crust. This layer is predominantly found on northerly aspects at tree line and in the alpine. The depth of both these layers makes skier triggering unlikely (maybe a heavy load on a thin spot in steep terrain, a cornice fall or rapid temperature change). The consequences of triggering any of these weaknesses would be severe.
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
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.