Regions
Vancouver Island.
Confidence
High - ample field data and confidence in weather forecast models.
Travel & Terrain Advice
Identify lee and cross-loaded features and approach with caution. Be cautious as you transition into areas of wind affected terrain. Avoid steep slopes below cornices.
Avalanche Summary
Avalanche control team reports from Mount Washington indicate some activity with control teams ski cutting small size one avalanches on steep isolated north aspects. These avalanches where wind slab on cross loaded features in open terrain at tree line. Failing on the exposed melt freeze crust, easily trigger and sensitive to human triggering.
Snowpack Summary
Variable surface conditions exist dependent on exposure to the wind. On open and exposed terrain, the majority is scoured to melt freeze crust. Areas protected from the wind have up to 50 cm of low density unconsolidated snow sitting on the melt freeze crust. Past moderate to strong wind from all directions with the last big wind event coming from the south west have transported a large amount of available low density snow. Numerous snow pack test have produced easy results failing on or just above the melt freeze crust initially buried on February 14. Observers have reported easy sudden planar results on compression tests and while travelling in avalanche terrain have experienced easily heard and felt snow pack settlements. The valentines day crust can be found down between 20 and 60 cm and the crust can be up to 80 cm thick. Below the crust well settled and strengthening snow
Snowpack Details
Surface: New low density snow. Upper: Melt freeze crust from 30 to 90 cm thick. Mid: Well settled. Lower: Well settled.
Past Weather
Cool conditions persisted with overnight lows below minus 10 and up to 20 cm of new snowfall. Winds continued from the north west with variable velocity ranging from light to strong. Overnight on Saturday strong south west wind transported available new and low density snow to north aspects.Sunday afternoon gave way to a variety of conditions including clear sky with sun, convective snow showers, graupel and or hail. On solar aspect and at lower elevation surface snow became moist with even the slightest touch of sun.
Weather Forecast
A strengthening low approaches the island region late Wednesday into Thursday bringing to the forecast area strong south east wind and moderate to heavy snowfall. Monday: 1 to 5 cm new snowfall. Temperatures - 10 overnight rising to 0 mid day, winds light to moderate south west. Freezing level 0 m rising to 800 m mid day. Tuesday: 1 to 5 cm new snowfall. Temperatures -3 overnight rising to near 0 by mid day, winds moderate west. Freezing level 500 m rising to 800 m mid day. Wednesday: 25 to 40 cm new snowfall. temperatures -5 rising to -1 mid day, winds Strong South East . Freezing level 250 m rising to 500 m mid day.
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.
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.