Avalanche forecast

Purcells

Mar 7 – 8, 2014Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

More storm = more avalanche danger! There are a few other problems that we are uncertain about. Check out the new blog post here.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–5
    Ongoing persistent avalanche activity proves layers formed about a month ago deserve respect and should still be in the front of your mind. Storm slab avalanches in motion or cornice falls may trigger the persistent weak layer.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    A punchy storm slab overlies a number of potentially weak layers. Expect increased reactivity in wind-exposed terrain. Warming and light rain may also have a significant destabilizing effect at elevations below the snow line.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Overnight and Saturday: Moderate westerly winds overnight and light to moderate precipitation. Heavy precipitation and strong southwest winds during the day. Freezing level rising to about 1800 metres.Sunday: Continued strong southwest winds and moderate to heavy precipitation. Freezing level rising to 2000 metres.Monday: Freezing level dropping overnight to about 1000 metres. Winds becoming light northwesterly as the precipitation ends in the morning.

Avalanche Summary

Storm slab avalanches continue to be reported running naturally. Most of the storm snow avalanches are size 1.5-2.0, however one was reported to be size 3.0 where the storm slab is now 80 cm thick. Explosives control released some large avalanches down to the early February persistent weak layer. There were also a couple of accidentally triggered storm slab avalanches, one that buried a sledder on a Northwest aspect in the alpine. Expect natural avalanche activity to continue over the weekend with forecast new snow and wind.

Snowpack Summary

Recent snowfall amounts have been highly variable throughout the region. In some deeper snowpack areas over 80cm of storm snow overlies weak surface hoar in sheltered areas, a sun crust on solar aspects and wind slabs in exposed terrain. On lee slopes these accumulations have been pushed into much deeper deposits by generally moderate southwest winds. Warming has added cohesion to the slab and wider propagations can be expected. At lower elevations rain has likely moistened snow surfaces. There is ongoing concern for a mix of weak surfaces which were buried on February 10th. This persistent interface lies between 60 and 160cm below the surface, and includes surface hoar, well developed facets and a mix of hard surfaces which remain widespread at all aspects and elevations. In some areas destructive avalanches are still a very real concern with ongoing reports of natural triggering, whumpfing and sudden/easy snowpack test results. The mid and lower snowpack are generally strong and well consolidated. Weak basal facets exist in many areas, but triggering has now become unlikely.

Regions covered