Regions
Vancouver Island.
Confidence
High - Weather models in agreement and good field data.
Travel & Terrain Advice
More new snow will fall Friday with cold temps, which will result in a slower bonding process to that which fell on Thursday. Continue to study the bond of all the storm snow to the old crust and now this potential new snow failure/shear. We will all be stoked to get out for what might be the last powder weekend of the season (OK hopefully not the last … ), but don’t let your desires to shred and your commitment to goals mask the potential dangers that exist. The avalanches don’t know its nearing the end of the season. Use the same cautious travel techniques you would as you entered a brand new snow pack, cause that’s what we essentially have with all this new snow. Areas like west Strathcona Park have the potential to see up to 55 cm of new! Moderate, gusting to strong, SE-SW winds have transported significant quantities of snow and the wind slab danger is high! Avoid large open lee slopes (W-N-E) and cross loaded features in the alpine, treeline and even open below treeline.
Avalanche Summary
Avalanche control on Mt Washington Thursday produced numerous size one wind slab avalanches with explosives and ski cutting on N-E aspects at treeline down approximately 5-20 cm.
Snowpack Summary
10-30 cm of new snow fell in the forecast region Thursday, luckily coming warm at first and then cooling during the event. This promoted moderate bonding to the old spring crust that we were all getting tired of playing on. Additional new snow Friday night with more forecast to fall during the day will come in cool and cold.
Snowpack Details
Surface: New low density snow with significant wind effect in open areas at all elevations. Upper: Warmer new snow (from Thursday) bonding moderately to the old crust. Mid: Moist snow, well settled cooling and becoming very stable. Lower: Well settled.
Past Weather
Lots of new snow…. approx 12 cm in the north, 17 cm in the east and a wonderful 27 cm to the west fell Thursday giving new life to our adventures. Yeah winters back! The new snow came in moist and warm (promoting some bonding to the spring crust) and cooled as it tapered off in the afternoon. Friday night saw more moderate snow fall with cooler temps. Winds have been moderate, gusting to strong from the SE-SW and widespread wind transport was witnessed all day Thursday.
Weather Forecast
More new snow Friday during the day and the temps will remain nice and cool over the weekend. Should be great conditions for adventures as long as we play safe and avoid areas of concern. Friday: 20 cm of new snow, winds moderate E-S, temps -4 to -6, freezing level 400 to 900 m. Saturday: 0-10 cm of new snow, winds light from variable directions, temps -3 to -7, freezing level 200 to 1000 m. Sunday: 2-6 cm of new snow, winds light rising to moderate SW, temps -4 to -7, freezing level 75 to 900 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.