Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
South Coast.
Forecast snowfall amounts are highly variable throughout the region with the southern areas expecting the see the highest accumulations. Pay attention to local conditions.
Confidence
Fair - Track of incoming weather systems is uncertain on Wednesday
Weather Forecast
Overview: The jet stream will flatten out allowing a series of pacific systems to impact the region with the south seeing the highest accumulations.Wednesday: Moderate snowfall / Moderate southwest winds / Freezing level at 1200mThursday: Moderate to locally heavy snowfall with the most intense precipitation falling late in the day / Strong to extreme southwest winds / Freezing level at 900mFriday: Moderate snowfall / Moderate to extreme westerly winds / Freezing level at 1200m
Avalanche Summary
2 size 2 slab avalanches (human triggered and natural) were observed in Marriott Basin in the Duffey Lake area over the last few days. No injuries were reported. The avalanches occurred around 2100m on south-facing terrain. Both were thought to have ran on a crust/facet interface. Check out our Incident Report Database for more details.
Snowpack Summary
Snowpack depths at treeline range from 130-170 cm in the South of the region, and from 80- 130 cm in the North of the region. Light amounts of new snow overlie a variety of old surfaces which may include surface hoar in sheltered terrain, wind-pressed snow in exposed areas, or a crust on previously sun-exposed slopes.In the north of the region, recent storm snow is sitting on weak layers of buried surface hoar which formed in early December. Facets from December's cold snap also seem fairly widespread in this part of the region. In some areas, these facets may co-exist with a crust. In thin snowpack areas, the facets may exist at ground level. These persistent weaknesses may likely wake-up with new snow forecast for the rest of the week.
Problems
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.
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.