Confidence
Fair - Timing or intensity of solar radiation is uncertain on Saturday
Weather Forecast
Friday: Chance of broken cloud in the morning with light snow in the afternoon - light to moderate southwest winds - freezing level at 900m Saturday: very light snowfall with a chance of intermittent sun until mid afternoon - light and variable winds increasing in the evening freezing level at 900m Sunday: scattered cloud - light southwest winds - freezing level at 900m Note: Solar radiation will have an increasing presence throughout the region over the forecast period. My best guess is that on Friday and Saturday morning there will be short lived localized bursts of sun with a more general clearing pattern expected for Sunday.
Avalanche Summary
Recent avalanche observations have been fairly limited due to inclement weather. Having said that, evidence of a widespread natural cycle to size 3.5 was observed on Wednesday. I expect ongoing natural avalanche activity throughout the forecast period, especially with forecast increasing solar radiation.
Snowpack Summary
Recent snowfall amounts have been quite variable throughout the region. Generally speaking, ongoing moderate daily amounts and moderate to strong southwest winds have contributed to reactive wind and storm slab development. This recent snowfall has added to a deep and cohesive slab that overlies weak surfaces that formed early February. This interface, which lies between 1 and 2 metres below the surface, includes a widespread surface hoar instability that, depending on aspect an elevation, may exist in combination with facets or crusts. These persistent weak layers have been reactive all week and remain a concern at all elevations. The weight of new snow, near-surface avalanches, sleds, and skiers may easily trigger these deeper weaknesses creating unexpectedly large and destructive avalanches.Large cornices have also formed and could act as triggers for slopes below.
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.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.