Winds are expected to increase, so watch for slab development in exposed terrain.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
THURSDAY: Cloudy with flurries starting in the afternoon, strong west winds, treeline temperatures around -17 C.FRIDAY: 5-20 cm of low density snow, strong west winds, treeline temperatures around -20 C.SATURDAY: Another pulse of snow with 5-30 cm possible, strong west winds, treeline temperatures around -23 C.
Avalanche Summary
Limited reports suggest triggering slab avalanches remains possible. Two skier triggered avalanches have been reported east of the divide the past few days. One was a small wind slab triggered in a steep gully and the other was a larger persistent slab (size 2) triggered low on a slope that propagated up and across the slope on a 50 cm deep crust. The later highlights the potential for persistent slab avalanches to have wide propagations.
Snowpack Summary
Cold temperatures are preserving fresh snow from the past week, with up to 60 cm in southern and eastern parts of the region and 30 cm in the Elk Valley. The snow has been deposited into harder wind slabs in exposed terrain, but remains low density in sheltered areas.The main question in the snowpack surrounds the layer sitting beneath the recent snow. The layer includes crusts on solar aspects and feathery surface hoar in sheltered terrain at and below treeline. The distribution of the layer, as well as the properties of the snow above it, is variable. The most suspect areas are where the wind has blown extra snow above this layer and on slopes with preserved surface hoar.The lower snowpack is composed of mostly soft sugary snow and a few early season crusts that have not produced significant test results recently.
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.