Regions
Banff Yoho Kootenay.
Avalanche conditions continue to be very tricky. The snowpack is dangerous and avoiding avalanche terrain is important right now. Avalanches have been occurring in low angled terrain. Strong winds and 10-15cm overnight will keep the danger elevated.
Weather Forecast
A weather system is moving over the region for Tuesday night bringing very strong winds from the SW, along with potentially 10 cm of new snow. The snow and wind should taper off by morning on Wednesday morning with perhaps some clearing by the afternoon. Temperatures will remain cool, from -10 to -15.
Snowpack Summary
Strong winds have raked the snowpack creating widespread wind effect and hard windslabs at treeline and above. The upper half of the snowpack is a dense slab overlying three weak layers (Jan 16, Jan 6, & Dec 15) that are a mix of facets, crusts and surface hoar down 75-125cm in the snowpack. These layers have been producing very large avalanches.
Avalanche Summary
No new avalanches were observed or reported today - but we continue to observe large avalanches that occurred within the last few days. Today on Vermillion Peak we observed an avalanche on a low angled slope at treeline that appears to have been remotely triggered by skiers. We also saw evidence of a large avalanche on a gully wall below treeline.
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.