Recent storm snow and strong winds have created fresh windslabs in exposed areas, particularly at treeline and above. Field teams measured some of these slabs at 90cm thick and displaying touchy results in snow profiles and stability tests.
Weather Forecast
Cool temperatures, with freezing levels remaining below 1100m for next 3 days. Light Southwest wind, gusting to moderate. Light scattered flurries amounting to less than 5cm.
Snowpack Summary
Up to 30 cm fell in the Icefields area on Thursday with moderate SW winds building touchy soft slabs on lee slopes at tree line and above. It rained at lower elevations making for a potential rain crust surface. This new snow rests on either a decomposed surface hoar layer that has formed the last few weeks or a facetted unconsolidated snowpack.
Avalanche Summary
Saturday natural activity noted up to size 3 running relatively far on a variety of aspects mainly in alpine. Explosive work was mixed results with sluff's to soft slabs up to size 2.5 on the range of aspects and elevations. On Friday, a skier accidental at Parkers Ridge, size 3, 1 involvement, no injuries. Depth 10-240cm x 400m x 400m.
Confidence
Due to the number of field observations
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.