New snow, northerly winds and cold arctic air are expected to increase the avalanche danger on Monday.Are you a member of Avalanche Canada? Join today at avalanche.ca/membership
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Cloud developing overnight combined with light southerly winds and freezing levels down to valley bottoms, and alpine temperatures around -10. A mix of sun and cloud during the day on Sunday with freezing levels rising up to about 1200 metres and light precipitation starting in the late afternoon. Cold arctic air is forecast to descend from the northeast resulting in 3-5 cm of new snow on Monday with alpine temperatures around -20 combined with moderate northerly winds.
Avalanche Summary
No new avalanches reported.
Snowpack Summary
Moderate northerly winds have created some thin windslabs from re-distributing the 5-20 cm of snow that is available for transport at alpine elevations. The surface snow has become facetted due to the cold overnight temperatures, and a new layer of surface hoar has been reported in some areas. Strong solar radiation has resulted in a thin breakable melt-freeze crust on southerly aspects at all elevations. The mid-February crust is reported to be strong, and has been stripped of new snow in many areas by northerly winds. The late-Jan crust/surface hoar layer (up to 100 cm deep) and the mid-January surface hoar (80-120 cm deep) are generally dormant, and chances of triggering these weaknesses have decreased dramatically. However, triggering may be possible with a large input such as cornice fall, or an avalanche stepping down, especially on slopes that see a lot of sun.
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.