Confidence
Fair - Due to variable snowpack conditions
Weather Forecast
Saturday: Inverted temperatures. Below freezing at valley bottom, slightly above freezing in the alpine. Strong ridgetop winds out of the NW. No precip expected.Sunday: Freezing level starts at valley bottom, rises to 1000m during the day. Winds start strong out of the NW, backing down to moderate by dinner time. Trace of snow in the morning.Monday: Below freezing at valley bottom, slightly above freezing in the alpine. Ridgetop winds mod/strong west. No precip expected.
Avalanche Summary
A few loose snow avalanches to size one occurring on upper elevation S, SW and even NE facing slopes were reported Wednesday.
Snowpack Summary
Intense recent winds have redistributed snow and created large cornices. The snow surface is now a mix of sastrugi, hard slab and soft slab in open areas. With the warm temps, slopes receiving direct sun are moistening in the afternoon. Surface hoar is continuing to form in protected areas too. Below this around 60cm of settled snow rests on a myriad of old surfaces (January 4th interface) that include sun crust on steep south and west facing terrain, surface hoar in sheltered locations at treeline and below and facets everywhere else. Reports indicate that this bond has strengthened over time and is now fairly tight. The overlying slab has also settled significantly. The bond at this interface seems to have strengthened somewhat with time. The overlying slab has also settled significantly. There are some reports of glide cracks on Mt Fernie, these mysterious phenomena should be given a wide berth.
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.