Regions
Vancouver Island.
No reports or observations of natural or human trigger avalanches over the past forecast period.
Small sloughing and some small slabs where present when ski cutting on very small features.
On Saturday, the Mount Washington Avalanche control teams reported explosives triggering a size 2.5 slab avalanche when blasting a cornice on the peak above the north bowl. Of note this large test did not step down to the PWL.
Past Weather
The past forecast period was a mixed bag of precipitation, wind effect and short periods of warming up to 1200 meters. At elevations 1200 meters and below the upper snowpack was becoming moist dense and settling. Remote telemetry and manual weather stations report approx. 20- 30mm of precipitation fell with the west side of the island seeing 40mm. Wind speed where moderate to strong from both the South East and South West.
Weather Forecast
A strong Northwesterly flow will continue over this next forecast period to deliver strong south west winds and precipitation. Freezing levels are expected to climb both Tuesday and Wednesday; precipitation in both the form of rain and snow will occur and are dependent on the freezing level. Initially the freezing levels will present as high when a storm front approaches, in the wake of the storm, cooling temps and dropping freezing levels should occur.**Monday:** 15-30 cm, Winds Strong from the South West, Freezing levels a high of 1500 meters.**Tuesday:** 15- 30 cm, Winds Strong from the South West, Freezing levels 1000 meters.**Wednesday:** 10-15 cm, Winds Strong from the South West, Freezing levels a high of 1700 meters.
Terrain Advice
**Please respect the avalanche/patrol team and workforce at Mount Washington, at no time is uphill travel or unsanctioned use of the private property permitted. We are lucky to have one of the least busy provincial parks in British Columbia and yes it may be a little more work than walking up a ski area run, its well worth the effort!**Be cognizant of snow conditions and utilize small slopes to test and investigate the recent storm snow and its reactionary properties.Monitor changing snow conditions as new storm snow will rapidly consolidate and present slab properties as temperatures rise.Careful and cautious route finding when transitioning from scoured areas into areas of wind loaded snow.Avoid traveling below and above cornice features as they are large and touchy.Avoid open and steep slopes during periods of warming and rain; even small loose wet avalanches will have enough mass to push a mountain traveler into gullies and over cliffs.
Snowpack Summary
Over the weekend intermittent moderate snowfall and intense wind transport was observed a storm system has delivered significant quantities of snow with extreme winds from the South East. The fact that the South east wind has been so intense will likely create significant loading on North West thru to West aspects, pay particularly close attention to this aspect as it will likely have very touchy wind slabs. Evidence of extreme wind transport of snow to North aspects is at all elevations.Overall snowpack depths have been measured from 200cm to 400cm. A variety of crusts exist in the upper snowpack. Numerous snowpack tests indicate that these crusts are now beginning to bond to the storm snowThe mid snowpack has an unreactive 20cm layer of facets that can be found down 100cm plus. This layer may be isolated to areas that are sheltered and at higher elevations above 1400 meters presents as a melt freeze crust/ poly grain layer.The lower snowpack is dense and very well settled as many reports for island backcountry users and numerous snow profiles have indicated.
Snowpack Details
- Surface: Wind affected snow, scoured on exposed South aspects with deep loading on North aspects.
- Upper: Storm snow and wind slabs from past storms can be found over a crust below 1500 m and over old storm snow above 1500 m.
- Mid: A 20cm layer of facets can be found down 100cm plus.
- Lower: Well settled and dense.
Confidence
Moderate - Increase in field observations and professional reporting, Increased MIN reports providing a range of good recreational information, much appreciated, please keep them coming.
Problems
Loose Wet
Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
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.