Regions
Vancouver Island.
Confidence
Moderate - Many variables and changes during this coming forecast period to predict and weather forecast models timing uncertain.
Travel & Terrain Advice
Big changes in conditions over this coming forecast period means extra evaluation will be needed by backcountry travelers. Wednesdays warm temps will potentially produce loose wet activity. Avoid exposure above terrain traps as these loose wet sloughs, though small will pack a heavy punch. Thursday the storm arrives with some warm temps and may even begin in some zones as mixed precipitation/rain. This warm new moist snow will have low stability at first and its slab potential will have some force to it even though it is not deep. Avoid exposure above terrain traps and avoid common trigger points like convex rolls, unsupported slopes and zones with weak points. By Friday strong winds from the NW will attempt to relocate the new storm snow from Thursday. The ability of the strong winds to move the new snow will be dependent on the snows moisture content and the temperature. If travelling in the backcountry be on the watch for how much snow is moving and building potential wind slabs on S-E aspects.
Avalanche Summary
No new avalanches during the past forecast period. Ski cutting steep unsupported convex features near ridge line at treeline on NW aspects and below treeline produced only loose surface sloughing of the top 5-7 cm demonstrating good stability.
Snowpack Summary
Very small amounts of new snow (1-2 cm) have fallen during the past forecast period on a very stable snowpack. Some upper snowpack layers present as potential future sliding layers as the next storm system arrives.
Snowpack Details
Surface: 1-2 cm of new snow preserved on non solar, moist on solar aspects (likely to create a thin crust). Upper: A layer cake of new snow, graupel (only in east and west regions) thin crusts (solar) and buried surface hoar. Mid: Multiple non reactive crusts and well settled snow. Lower: Well settled.
Past Weather
The convective activity which resulted in pulses and surges of weather over the previous forecast period eased over the past three days. There were light variable winds and only small amounts new snow fell. Cold temps overnight and warm temps during the day have helped to create stable conditions.
Weather Forecast
Temps rise as the next storm system arrives bringing moderate amounts of new snow. As the system ends winds fully switch directions and temps drop back to seasonal. Wednesday: 0 to a trace of new snowfall, light to moderate SE winds, temps -5 to +3, freezing levels 500 m rising up to a significant 1850 m. Thursday: possible light rain and 4 cm of snow to the north and 10-15 cm of snow/ mixed precipitation to the east and west regions, moderate winds from the SE then a big switch to strong from the NW, temps 0 to -3.5, freezing levels 700 to 1225 m. Friday: 1-3 cm of new snow, moderate NW to SW winds drop to light S to SE, temps -3 to -7, freezing levels 0 to 1000 m.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.