Avalanche forecast

Northwest Inland

Apr 19 – 20, 2015Avalanche Canada
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Avalanche danger

Tue
Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

This is the last avalanche bulletin with danger ratings for this region this season.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Strong winds have redistributed recent storm snow into wind slabs on leeward slopes. They are especially touchy where they sit on buried facets, surface hoar and/ or crusts. Cornices are large and may weaken with solar radiation.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–5
    Additional snow loading on the mid- March persistent weak layer could bring it back to life. Smaller slab avalanches may step down to this layer, initiating large and destructive avalanches.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–3
    Solar radiation and warmer temperatures will deteriorate the snowpack quickly. Travel on sunny slopes early, and watch for signs of instabilities like avalanches, moist surface snow and snowballing.

Confidence

Poor - Due to the number of field observations

Weather Forecast

Warm and windy overnight with overcast skies and some light precipitation. Coastal areas should see up to 15 mm of precipitation on Monday with a freezing level around 1800 metres. Inland areas are likely to get less than 5 mm of precipitation as the system moves south along the coast and is not forecast to push inland. Stormy conditions are expected to continue in the Northwest.

Avalanche Summary

Slab avalanches up to size 2 were reported in the Mt. Leach area on mostly north facing slopes. On Saturday, touchy wind slabs and storm slabs are likely, especially in areas that receive higher snowfall amounts. If the sun pokes out, solar radiation will be strong and deteriorate the upper snowpack. Watch overhead hazards like cornices, solar triggered loose and slab avalanches.

Snowpack Summary

Recent storm snow has likely formed touchy storm slabs. Strong westerly winds have redistributed this new snow and has formed wind slabs on leeward slopes and behind terrain features. Solar aspects may have a sun crust from recent localized solar radiation. The lack of bond between the new wind slabs and storm slabs over the older snow surfaces buried on April 9 th (surface hoar, crusts and facets) are the primary concern. The March 25th surface hoar / crust layer is reportedly unreactive, however; it should remain on your radar as it may re-awaken with the new load of snow, wind and effects from warming. Large ripe cornices are also of concern and will be a problem with additional loading, especially when the sun and warm temperatures come back.

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