Regions
Vancouver Island.
Small Loose wet avalanches reported on steep solar facing terrain as daytime air temps rise up into Treeline elevation band.
Past Weather
Generally mild air temperatures and day time highs raised the freezing levels to Treeline over the past several days. The generally warm air temps have promoted a great deal of consolidation to the upper 1M to 2M of the Vancouver Island mountain snowpack. A returned cooling trend returns for the next 24hrs to 48hours.
Weather Forecast
A major storm and wind event on Sunday has redistributed snow and created a dynamic avalanche risk management problem as Extreme winds shifted from South to North throughout the storm event. Expect a returned cooling trend to return for the next 24hrs to 48hours. Monday: No snow expected throughout forecast area, Winds Moderate and gusting to Strong from the NW, Freezing level 850MTuesday: No snow expected throughout forecast area, Winds Moderate (gusting to Strong) from the NW, Freezing level 1,000M (except mid-North Island where Freezing Level will rise to 1300M)Wednesday: No snow expected throughout forecast area, Winds Light from the SW, Freezing level 1,550M
Terrain Advice
Wind slabs will be primary hazard for the next 24 to 48 hours.Practice patience and allow time for new storm instabilities to stabilize prior to committing to any steep terrain.Plan routes and choose terrain that is low angle and supportive as you begin to venture into unmodified and uncontrolled snowpack and terrain.Identify and avoid travel either above or below cornice features.Adjust travel plans to ensure avoidance of slopes during warming events (particularly Wednesday).
Snowpack Summary
Loading in the form of new snow and extreme winds has promoted wind slab development on North and South downwind terrain. The new snow rests on a generally well settled and firm snowpack.
Snowpack Details
- Surface: 5cm to 25cm of soft new powder snow
- Upper: Well bonded and dense moisture laden snowpack.
- Mid: Well settled due to melt freeze cycle snowpack has undergone.
- Lower: Well settled and dense.
Confidence
Moderate - Weather models in agreement. Limited public observations submitted to VIACS and/or MIN at Avalanche.ca
Problems
Cornices
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
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.
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.