Avalanche forecast

South Coast

Dec 26 – 27, 2011Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–5
    Wind slabs have developed in exposed lee and cross-loaded terrain and may be quite reactive, especially where they over-ride last weekends rain crust or weak facets (sugar snow) from the early December dry spell.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Weaknesses may exist within or under the new storm snow. Natural avalanches will become more likely with each successive storm.

Avalanche Summary

Fresh wind slabs and cornices may be sensitive to human-triggers and the likelihood of natural activity will increase with the forecast weather.

Confidence

Fair - Timing of incoming weather is uncertain

Weather Forecast

A series of frontal systems will continue to affect the region over the next few days. In general, expect 15-20cm of snow each 12 hour period, with moderate to strong W-SW winds, and fluctuating freezing levels (FL). Tuesday: 15-30cm, heaviest in the evening/overnight. Strong SW winds, rising overnight. FL around 800-1000m gradually rising. Wednesday: 20-30cm, heaviest overnight. Strong W-SW winds. FL rising to 1600m. Thursday: 15-25cm. Strong SW winds. FL lowering to 1000m.

Snowpack Summary

Wind-exposed slopes are predominately scoured and pressed, with pockets of wind slab from 20 to 50cm deep on North to East aspects at treeline and in the alpine.This new storm snow overlies a weak rain crust that formed last weekend. This crust extends to treeline elevations and overlies buried surface hoar and/or facets 10cm below. Generally speaking, confidence in this interface is growing, especially since it has'nt seen a significant load at the elevations where it exists. In the alpine where the crust does not exist, a stiffer wind slab may over-ride surface facets that formed during the early December dry spell. Persistent weaknesses seem to be less of a concern in the Cascades (Coquihalla and Allison Pass).The mid and lower snowpack are generally well-settled and strong.

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