Regions
Vancouver Island.
On Friday, North aspect terrain produced two natural size three windslab avalanches between 1300 and 1500 meters.
Avalanche control teams at Mount Washington utilized explosives to trigger numerous size 2 windslab avalanches.
Skier trigger size 1 windslab avalanches continued to linger and reported on north west facing terrain just below 1300 meters on Sunday.
Past Weather
A significant storm event delivered on average over 100 centimeters of snow combined with strong South west wind. The western leading edge of the island mountains received over 150cm of new snow. Temperatures remained cool with freezing levels reaching 1200 meters but mostly stayed below 1000 meters.
Weather Forecast
Initially unsettled weather will bring clouds and light snowfall. By Tuesday evening a ridge of high pressure will bring clear sky and no new precipitation. Monday: 1 to 5 cm , Winds Moderate from the South East, Freezing levels at 500 meters rising to 600 meters.Tuesday: Trace amounts of snow, Winds light to moderate from the South East, Freezing levels at sea level with a day time high of 600 meters.Wednesday: No new precipitation , Winds Light to Moderate from the North West, Freezing levels at seas level with a daytime a high of 1000 meters.
Terrain Advice
Caution when transitioning into terrain with recent wind loading and steep convex roll features.Avoid direct solar terrain during periods of sunshine and daytime warming.Caution above or below cornice features, recent loading has continued to build upon already very large cornices.
Snowpack Summary
Storm snow amounts between 80 to 150 centimeters has been transported by the wind and can be found on North west thru to North east aspects. This new load of snow has begun to settle and overlies a previous crust surface and has either naturally released during the storm event or is moderately bonding.Terrain exposed to the wind is stripped and scoured. The persistent slab from February is now down over 200 centimeters and is dormant and currently non reactive to testing . Below the snowpack is dense and well settled.
Snowpack Details
- Surface: A variety of surfaces, new low density snow, wind scoured at upper ridge tops and wind loaded on north aspects.
- Upper: Settling new snow between 100 and 150 centimeters.
- Mid: Old unreactive crusts, overall dense and well settled.
- Lower: Well settled and dense.
Confidence
Moderate - Forecaster field observations and numerous reports. No alpine observation, uncertainty with alpine windslab stability .
Problems
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.