Conditions are expected to improve over the forecast period. Make observations continually as you travel.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
A benign yet cool weather pattern has set up and will continue for the forecast period. For each day, expect a mix of sun and cloud with isolated flurries, although slightly higher accumulations are possible in the far south of the region. Ridgetop winds are expected to remain light while alpine temperatures should remain between -12 and -16.
Avalanche Summary
Evidence of a few natural wind slab avalanches to size 2 was observed in lee alpine terrain on Monday and Tuesday. The avalanches occurred in response to new snow and wind on the weekend.
Snowpack Summary
Throughout last weekend there was up to 20cm of new snow. Strong southerly winds have redistributed much of this snow into soft wind slabs in exposed lee features in the alpine and at treeline. Between 40 and 80cm below the surface you'll likely find a layer of weak buried surface hoar which is most prominent between 1400m and 1800m although it may extend higher in the mountains south of Invermere. Snow pit tests suggest that human triggering of this interface is becoming unlikely, although a release at this interface could be destructive in nature.
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.