Regions
Vancouver Island.
During a flight check of the island alpine southern zone a widespread natural loose wet cycle in the Alpine and tree line on steep solar features up to size 2.5 was observed. Loose and wet snow in steep terrain was observed gaining mass in gulley features and running to mid and lower paths.
Past Weather
A series of cool nights and warm and sunny days with no precipitation.
Weather Forecast
A south west flow will deliver this forecast period overcast sky and periods of flurries for most days, Forecast models indicate that increased precipitation amounts are likely in the northern half of the forecast area.Friday: Trace amounts of snow. Winds Light to Moderate from the Southwest, Freezing levels 200 meters rising to 800 meters. Temps at 1500 meters -6Saturday: 5 to 15 cm of snow, Winds Moderate to Strong from the South West , Freezing level 700 meters rising to 1000 meters. Temps at 1500 meters -4Sunday: Trace amounts of snow. Winds Moderate to Strong from the North West, Freezing levels 400 to 1000 meters. Temps at 1500 meters -4
Terrain Advice
Caution when transitioning into areas that are being loaded with new snow and wind.Avoid travelling both above and below cornices.As you descend in elevation , the loose wet avalanche problem is likely to present.
Snowpack Summary
Past warm and sunny conditions followed with periods of overnight cooling have continued to slowly settle and strengthen the entire snowpack. All snow surfaces including north aspects became moist, with solar aspects becoming unconsolidated down 10-15cm. A cooling trend is expected to refreeze the upper snowpack and proved a new surface for incoming precipitation to slide on.
Snowpack Details
- Surface: Moist, expected to refreeze into a meltfreeze crust
- Upper: Well settled with a number of unreactive laminated crusts
- Mid: Well settled and dense.
- Lower: Well settled and dense.
Confidence
Moderate - Excellent field observations of past warming cycle and good agreement between forecasts weather models for this area.
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.