Regions
Vancouver Island.
No new big avalanche activity reported over the past two days. Some minor loose wet activity up to size 1 on solar asp at treeline and all asp below treeline. Tree bombs and pinwheeling.
Update for last weekends avalanche activity in the Cain region. One very large isolated avalanche size 2.5 to 3 was noted off the side of Table mountain, just above the Table Hapush col. A couple size 2 and a few size 1 for Cain's west bowl were reported as either human or naturally triggered but the triggers were not confirmed. The estimated timing of these events was either Friday or Saturday.
Past Weather
Small amounts of new snow fell and were warmed by mild temperatures. Winds were light to moderate from variable directions.
Weather Forecast
New snow! Starting with moderate and climbing to heavy snowfall is the forecast for the next three days. Temps will be cool and strong rising to extreme SE winds will accompany the storm cycle. Wednesday: 1 to 15 cm of new snow with greater amounts for Strathcona Park, the north and the west regions (least for the eastern side of the island). Winds strong to moderate SE. Temps for 1500 m -5 to -1. Freezing levels 550 to 950 m.Thursday: 6 to 20 cm of new snow. Winds strong to extreme SE. Temps for 1500 m -1 to -4. Freezing levels 500 to 1100 m. Friday: 16 to 34 cm of new snow. Winds ranging from light to strong S through E. Temps for 1500 m -4 to -1. Freezing levels 600 to 1100 m. Estimated snowfall totals by the end of the day FridayMyra region 63 cmMt Washington zone 36 cmMt Cain 35 cmArrowsmith 24 cm5040 68 cm
Terrain Advice
Snow fall amounts are forecast to climb significantly over the next three days. Carefully analyses how much snow is above the old crust, to estimate the potential size of avalanche one can expect. Avoid wind loaded aspects (ie N-W slopes) Thursday and Friday as strong to extreme winds will transport significant amounts of snow to these lee slopes, especially just down from ridge tops and on the lee sides of cross loaded features. Bowls and gullies will load up with wind transported snow and magnify the potential size/depth of an avalanche. Give cornices a with berth as they continue to grow along treeline and alpine ridges. Avoid travel above or below these features.
Snowpack Summary
Well unfortunately we did not get the moderate snowfall that was forecast over the past three days. Only 2 to 10 cm of new snow fell on our crust in the island hills. This new snow is moist on all aspects from approx 1400 m and below. On solar aspects the moist snow can be found even higher. High non solars escaped the warm up and some nice preserved cold snow can be found.
Snowpack Details
- Surface: Mainly moist new snow bonding moderate to the old crust, some winds slabs still linger in the alpine.
- Upper: A crust with variable support to skis and unsupportive to sleds and foot traffic. Some dry loose snow under.
- Mid: Well settled with some old crusts
- Lower: Well settled
Confidence
High - Good amounts of field data and weather models in agreement. A crust overlies a very well settled snowpack so we will mainly be dealing with new snow instabilities.
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.
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.
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.