Confidence
Fair - Track of incoming weather systems is uncertain
Weather Forecast
Overview: A series of disturbances are embedded in a west/southwesterly flow which will bring continued snowfall to the region. There is some model disagreement in the track of the systems; however, southern areas of the interior are expected to see the highest accumulations.Tuesday: Light snowfall / Moderate westerly winds / Freezing level at surfaceWednesday: Light to locally moderate snowfall / Light ridgetop winds / Freezing level at surfaceThursday: Light snowfall / Light ridgetop winds / Freezing level at surface
Avalanche Summary
Numerous size 2-2.5 sled-triggered slab avalanches occurred in the Valemount area over the last week. The February 10th interface was the culprit in these events. Isolated reports of remotely triggered avalanches in neighbouring regions also suggest that large slab avalanches on the February 10th interface are still a real possibility. A couple of size 2 wind slab avalanches were also noted on northwest facing terrain on Sunday. They formed in response to redistribution of surface snow due to strong winds over the weekend.
Snowpack Summary
Light to locally moderate amounts of new snow overlie small surface hoar crystals in sheltered areas, a sun crust on solar aspects and recently formed wind slabs in exposed terrain. Initially, these new accumulations are expected to be reactive as wind slab in pockets of exposed terrain. Once the new slab develops, more widespread storm slab activity can be anticipated.There is ongoing concern for a mix of weak surfaces which were buried on February 10th. This persistent interface lies up to a metre below the surface, and includes weak surface hoar, well developed facets and a mix of hard surfaces which remain widespread at all aspects and elevations. Although natural avalanche activity has tapered-off at this interface, destructive avalanches are still a very real concern with ongoing reports of rider-triggering and sudden snowpack test result results. For the most part, the mid and lower snowpack are strong and well consolidated. Weak basal facets exist in some areas, but triggering has now become unlikely.
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.