Boletín de aludes

Vancouver Island

Jan 27 – 28, 2020VIAC
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Archivado · caducó 7 years ago

Peligro de aludes

Tue
Wed
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Lo esencial

Wet loose avalanches on steep unsupported terrain have been reported (size 1.5). Ski cutting produced size 1 avalanches on Storm Slab and wind slabs on unsupported terrain. (Size 1).

Problemas de aludes

  • Wind Slabs

    • Todas las altitudes
    Probabilidad
    Possible
    Tamaño
    1
    Major precipitation in the form of storm snow and strong winds from the South could promote wind slab instabilities (particularly in leeward or down wind areas on Vancouver Island on Monday and Wednesday. . Expect all Alpine and Treeline environments in leeward/down wind terrain to be likely areas to trigger a wind slab avalanche on Monday, Tuesday and Wednesday.

  • Cornices

    • Todas las altitudes
    Probabilidad
    Possible
    Tamaño
    1
    Touchy cornice features have been building and will be predominantly found on North aspects. Found in both alpine and Treeline terrain, triggering of this avalanche problem is likely from light loads such as skiers or sledders. Be leery of recreating above or below cornice features at this time.

  • Storm Slabs

    • Todas las altitudes
    Probabilidad
    Possible
    Tamaño
    1
    Major precipitation in the form of storm snow on Vancouver Island on Monday, Tuesday and Wednesday will cause instabilities in the snowpack. Approach Alpine and Treeline elevations as (human triggered avalanches likely) and the Below Treeline environment as (human triggered avalanches possible).

  • Deep Persistent Slabs

    • Todas las altitudes
    Probabilidad
    Possible
    Tamaño
    1
    Snowpack assessments revealed a deep persistent slab problem. The likelihood of triggering this layer is unlikely given that it is 120cm down at the Below Treeline elevation band. This layer is likely deeper at Treeline and Alpine environments and no longer a potential hazard to recreational skiers or sledders. Nonetheless, it is wise to continue practicing appropriate group management techniques and only exposing 1 person to the avalanche slope at a time. The reactivity of this layer is such that it would require a large trigger to initiate such as multiple sleds on the slope at the same time or multiple skiers at the same time and or / major cornice fall hitting a slope.

Snowpack Summary

Good quality snowmobiling and skiing will reside primarily at higher elevations on all aspects due to the previous warm weather and rainfall events of the last several days. Sundays major wind events have created major wind slab problems in lee (down wind) areas and Treeline and Alpine environments. The snowpack is extremely well consolidated as a result of all the moisture we have received. Unfortunately, lower elevation bands below Treeline will likely hold a good deal of dense moisture laden heavy snow from Thursdays rainfall up to the Alpine and as the freezing level continues to hover around mid-mountain. The Treeline and Alpine environments, despite holding good snow could also present wind slab and storm slab potential as as we are forecasted to receive up to 30cm/1 foot of new snow or more each day these next several days as well as some strong wind events which may cause wind slabs at Treeline and Alpine.

Past Weather

Extreme snow transport took place today (Sunday) and contributed to major leeward (down wind) loading on Northerly aspects. There exists 10cm - 40cm of storm/wind driven snow on Thursdays (Jan 23rd) rain event and is reactive.

Weather Forecast

Monday 10 - 50 cm, Winds Moderate from the South East, Freezing level 1000 meters.Tuesday 5 - 20 cm, Winds Light from the South East, Freezing level 1350 meters.Wednesday 10 - 40 cm, Winds Light to Extreme from the South, Freezing level 1400 meters.

Terrain Advice

Natural Avalanches possible. Human triggered avalanches likely in Alpine and Treeline Elevation bands. There is a good amount of precipitation expected over the next several days throughout Vancouver Island. Be aware as you move through the terrain for shooting cracks and signs of instability (including new avalanches) especially at Treeline and Alpine elevation bands. Convex unsupported terrain features in leeward (down wind) terrain would be an area to be highly cautious of when navigating through the backcountry. Allow for an additional 36-48 HRS before stepping onto leeward terrain (downwind) areas particularly if the forecasted precipitation of 30+cm of new snow AND/OR signs of snow transport by strong winds exists in your area.If these visible and audible (whumpfing) clues exist in your area, it will be important to find lower angle terrain (generally under 30 degrees) and or ski/sled in more densely vegetated (treed) areas away from these obvious clues of snowpack instability. Check the website ATES PLANNING section for Simple Terrain options on our website.

Snowpack Details

  • Surface: 10cm - 30 cm of light, fluffy dry snow and is bonding poorly to crust below
  • Upper: Well bonded upper snowpack, extremely dense and moisture laden (rounding)
  • Mid: Well consolidated - 2 laminated crusts (down 60cm) and (down 120 cm) are reactive to testing but well bridged by rounded upper snowpack
  • Lower: Well Settled

Confidence

High - Weather models in agreement, Moderate field data available, insufficient Weather station data.

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