Conditions in the alpine are variable across the region. Areas with minimal wind loading are MODERATE.
Weather Forecast
Thursday: One more day of frigid cold to endure - although some minor warming may creep into the far south. Light winds. No precipitation.Friday: Light snow starting late in the day. Moderate south-westerly winds and temperatures rising slightly. Saturday: Continued light to moderate snowfall. South-westerly winds.
Avalanche Summary
A natural avalanche cycle to size 2.5 was reported on alpine slopes in the northern Purcells, failing in response to an overnight wind event. Skiers have been triggering soft slabs in steep terrain in the size 1-1 .5 range over the past few days, however many observers say that the snow remains mostly cohesionless due to the intense cold.
Snowpack Summary
20-45 cm of low density storm snow has been redistributed by mainly south-westerly winds. Cold temperatures have limited the widespread development of storm slabs, but wind slabs and cornices of variable reactivity have built up. Below the storm snow are various surfaces including facets, surface hoar in sheltered areas, wind crust, soft slabs and hard slabs. The mid-December surface hoar/facet persistent weakness, now down around 50cm on the eastern side of the range and as deep as 160cm on the western side, is still causing operators concern, especially in shallow snowpack areas. The consequences of a failure on this layer would be large. Facets and depth hoar exist at the base of the snowpack.
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.
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.
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.