Regions
Vancouver Island.
Confidence
High - weather models align and agree
Travel & Terrain Advice
Cornices will become weak when temperatures warm and the sun is radiating. Identify and seek terrain options when entering areas with recent wind loading (North aspects). Caution on South aspects when the temperature warms and solar radiation begins to rapidly effect the slope.
Avalanche Summary
Numerous loose wet avalanches all aspects and elevation from the alpine to below tree line with a few gaining enough mass to be large in size (2). One wind slab on north aspects below 1500 meters on thin steep rocky terrain approx crown of 40 cm small in size (1). Cornice tabs are dropping and a few failures were noted at treeline on north aspects and one initiated a small loose wet avalanche.
Snowpack Summary
The upper surface snow received significant solar effect and warming creating a wide spread melt freeze crust that is present on all aspects and all elevations. Recent snow fall and wind loading has deposited a variety of new snow depths on primarily north aspects. In the alpine and at tree line on ridge tops and lee features have very large cornices with weakening tabs that will present problems as the spring weather cycle begins. The upper snow pack is moist to wet and in large open areas lee depositing exceeds 100 cm. The march 22 melt freeze crust is now buried down over 150 cm and shows little in the way of reaction and at this time could be considered dormant. The lower snow pack is well settled and dense.
Snowpack Details
Surface: 5 to 10 cm thick melt freeze crust. Upper: Moist to wet. Mid: March 22 melt freeze crust can be found down 150 to 200 cm. Lower: Well settled and dense.
Past Weather
Moderate to heavy snow fall with strong southerly winds, followed by warming temperatures, clear sky and sunshine. On Monday night freezing levels dropped to 400 meters and alpine temperatures hovered around minus 5.
Weather Forecast
A stable weather system with some daytime convective alpine snow showers. Mostly clear conditions and overnight cooling, beginning Friday a change to a southwesterly flow will deliver to the forecast area light to moderate amounts of precipitation and south west wind. Wednesday: no new snowfall temp -2 to 3, winds light south east, freezing level to 1200 m. Thursday: no new snowfall temps -2 rising to 6, winds light south east, freezing level to 1500 m. Friday: 5 to 10 cm of snowfall temps 0 to +3 winds light to moderate south west , freezing level to 1300 m.
Problems
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.
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.
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.