Regions
Vancouver Island.
Confidence
Moderate- few alpine but good treeline and below treeline observations, weather forecast models mainly in agreement.
Travel/Terrain Advice
Avoid wind loaded slopes and features with north-west aspects that gather wind transported snow. New snow will increase the size/hazard that exists on the wind slabs created Sunday, so keep an eye on actual new snow amounts Monday-Wednesday. Loose snow sloughs can entrain additional snow adding to hazard. Avoid slopes that will magnify loose avalanches like gullies and bowls below steep terrain.
Past Weather
Rain up into the alpine Friday saturated the upper snow pack. Cooling temps Saturday brought new snow to elevations above 1000 m (2-10cm). Sunday 5-15 cm of new snow fell in the mountains with larger amounts in the west and south regions and less to the north. Strong (up to 70k mph) winds from the south-east accompanied the new snowfall.
Avalanche Summary
Small size 1-1.5 loose dry avalanches were reported with control work on Mt Washington Sunday, running on the skier compacted crust down approximately 10cm. Intentional ski cuts in open treeline terrain elsewhere produced small to very small wind slab avalanches up to size 1 on the lee of wind loaded rolls and features running on the new crust created by last Fridays rain event.
Snowpack Description
Surface - Variable surface conditions from moderate density new snow in wind sheltered zones to exposed crusts on wind stripped alpine and treeline ridges. Upper - New snow, blown by Sundays winds, has formed firm wind slabs on lee (north-west facing) features in the alpine and exposed treeline. Approx 1-15cm on new snow fell on the forecast area Sunday, capping the newly formed rain crust from Fridays rain event. The bond between the new snow and crust was poor in test on Sunday on significantly steep terrain.Mid - The new snow and crust buried on Jan 7th is now bridging and limiting concerns surrounding the mid Dec and mid Nov crusts. The moist mid snowpack seams very stable.Lower - Well settled.
Weather Forecast
Warm temps and slightly high freezing levels Monday morning will begin to drop by mid day bringing new moist snow. Tuesday-Wednesday will see increasing snowfall and very low freezing levels and temps. This new snow is very welcome to our lower than seasonal snowpack and should provide excellent conditions and powder. Mon - 10-20 cm of new snow. Winds light to moderate south to south east trending to north west. Freezing levels of 1400-800 m Tues - 2-6 cm of snow. Winds light to moderate south west-north west. Freezing levels of 550-950 m Wed - 0-15 cm of new snow. Winds light west to south east. Freezing levels of 175-850 m
Problems
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
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.