Avalanche forecast

South Columbia

Dec 15 – 16, 2013Avalanche Canada
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Avalanche danger

Tue
Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–5
    Moderate temperatures may increase the reactivity of an assortment of persistent weaknesses buried in the mid and upper snowpack. Triggering a persistent slab may have nasty consequences.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    Ongoing snowfall, wind and moderate temperatures have added to a developing storm slab problem. Watch for increased reactivity in wind-affected terrain or at elevations where the upper snowpack has been affected by warming.

Confidence

Fair - Intensity of incoming weather systems is uncertain on Tuesday

Weather Forecast

Monday: Light snowfall / Moderate westerly winds (with extreme gusts) / Freezing level at 800mTuesday: Moderate snowfall / Moderate southwesterly winds (with extreme gusts) / Freezing level at 800mWednesday: Possible clearing / Light winds / Freezing level at valley bottom

Avalanche Summary

On Saturday, several natural storm slabs to size 2 were reported to have run on a variety of aspects and elevations. There have also been a number of size 2.5 and size 3 storm slabs which ran on north and south facing alpine terrain along the highway corridor through Rogers Pass. They occurred in response to ongoing snowfall, wind and rising temperatures.

Snowpack Summary

Although recent accumulations have been highly variable, up to 60cm of snow now overlies the weak faceted crystals or small surface hoar which formed during the last cold snap. Rising temperatures are reported to have enhanced slab properties forming cohesive surfaces and creating a more reactive "upside-down" snowpack. Moderate to strong southwest winds have created wind slabs in exposed high elevation terrain.As of late there has been no reported activity on the late-November interface which consists of sun crusts on steep south facing slopes and surface hoar in sheltered areas. This layer, buried between 60-80cm below the surface, is generally considered to be "stubborn" to trigger; however, avalanches at this interface could have nasty consequences.Weaknesses towards the base of the snowpack are mostly thought to be dormant at this time.

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