Avalanche forecast

South Rockies

Apr 10 – 11, 2012Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Sunny skies and freezing levels as high as 3500 m are continued Wednesday. As the snowpack deteriorates, natural avalanche activity is to be expected. Solar induced wet slabs may be large and run full path.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–5
    The odd deep slab could still be out there, I'm still suspect of steeper unsupported slopes & places where the snowpack goes from thick to thin, especially near ridge crest and around rock outcroppings.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely - Certain
    Size
    1–4
    Strong sun and rising freezing levels are forecast for Wed. Watch for loose wet slides; especially on Southerly slopes. There may be potential for deep slab avalanches on slopes that bake all day. Cornices are weak, and could trigger slopes below.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–6
    A cohesive slab up to 100 cm is sitting on the March 27th interface. With little freeze and skyrocketing freezing levels, wet slabs are likely to occur on this layer. They may run to ground if the snowpack becomes isothermal at lower elevations.

Avalanche Summary

Some loose snow activity on a SE facing slope was reported, but, there is surprisingly little avalanche activity in the region currently.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Wednesday

Weather Forecast

The weather pattern will begin to change tonight as a dominating ridge of high pressure will start to break down. This will allow a strengthening, moist SW flow to enter the region. Wednesday: Freezing levels will continue to be near 3500 m, with sunny skies and light-moderate Southerly winds. Thursday: Light precipitation should begin later Wednesday night, while Thursday may bring moderate-heavy amounts. Freezing levels will fall 1800 m. Ridgetop winds light gusting moderate from the West. Friday: Lingering, light precipitation through the day. Freezing levels will rise to 2000-2500 m, with sunny skies in the afternoon.

Snowpack Summary

Spring like weather, and conditions have promoted settlement and bonding within the upper snowpack. Below this a cohesive slab 60-120 cm (depending on the drainage) sits on the March 27th interface. Our field team was out in the region on Tuesday; they were able to find the March 27th interface down around 95cm but test profiles did not produce any results on this layer. At 1900 m on a NE aspect the upper 10cm surface snow has become moist, below this the snow is still dry. All other aspects the snow has become moist. Without significant re-freeze the snowpack may continue to deteriorate through Thursday. Natural avalanches are expected. Large cornices loom over many lee slopes, and could trigger slopes below. Glide cracks are a concern, be sure to give them a wide berth as they are very sensitive and could fail at any moment.

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