Regions
Vancouver Island.
This weekend is beginning with some spice. Thursday's active avalanche control program at Mount Washington, reported numerous size 1 to 1.5 storm slab avalanches triggered by ski cuts. Explosive control on a cornice feature triggered a size 2 avalanche, all on north thru to west aspects. A skier accidental avalanche was trigger on a North east aspect at the apex of a convex roll, no injuries have been reported or other details.
Past Weather
A strong cold front passed rapidly over the forecast area delivering intense snowfall and strong wind.
Weather Forecast
Unstable weather in the wake of the recent storm will bring to the forecast area a mixed bag of clouds moderate snowfall and a few periods of sun. Friday: 10-15 cm of snow, Winds Light from the South East, Freezing levels to 1000 meters.Saturday: 5 to 10 cm of snow, Winds Moderate from the South West, Freezing levels to 1000 meters.Sunday: 5 to 10 cm of snow, Winds Light from the South East, Freezing levels 1000 meters.
Terrain Advice
Careful and cautious route finding when transitioning into wind effected convex rolls or steep terrain.Default to lower angled terrain if you observe wind drifted snow, active snow transport, or snowfall amounts that exceed 30 centimeters.If precipitation amounts exceed forecast, expect hazard rating to be higher.
Snowpack Summary
New snow has fallen on a variety of old surfaces including solar crusts and old surfaces that are hard and planar.
Snowpack Details
- Surface: New snow of up to ten centimeters overlies over a thin sun crust on solars and on old hard snow on non solars.
- Upper: 30 to 100 cm of settled storm snow with a few thin crusts sandwiched between on solar aspects.
- Mid: An old crust with weakening snow crystals above and below the crust as it continues to degrade.
- Lower: Well settled and dense.
Confidence
Moderate - High value field data and feedback, but the weather models have a high degree of variability.
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.
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.