Avalanche forecast

Purcells

Apr 21 – 22, 2013Avalanche Canada
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Archived · expired 13 years ago

Avalanche danger

Tue
Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

The Public Avalanche Forecasts come to an end on Monday. Starting Tuesday you can find spring messaging under the "Forecast Details" tab below.See you next Season!

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Touchy wind slabs exist on lee slopes at treeline and above. Cornices are huge and remain a concern, especially with daytime warming which will likely make them weak. They threaten slopes below.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–6
    A weak interface buried in the upper metre of the snowpack can create surprisingly large avalanches. It's been reactive in nearby regions, and remains a concern with professionals. Be cautious in steep, alpine terrain.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Loose wet avalanche activity is likely with rising freezing levels and clear sunny skies. Conditions can change quickly with timing, aspect and elevation.

Confidence

Fair - Due to limited field observations

Weather Forecast

An upper ridge stalls off the coast bringing sunny skies and dry cool conditions through Tuesday. By mid-week freezing levels will rise to 2000 m.Monday: Mostly sunny skies. Ridgetop winds will blow light from the NW and freezing levels will rise to 1800 m. Tuesday: Broken cloud cover and a chance of flurries. Ridgetop winds moderate from the NW and freezing levels 1800 m. Wednesday: The stationary ridge of high pressure continues bringing sunny skies and freezing levels up to 2000 m. Ridgetop winds will blow light from the SW.

Avalanche Summary

No new avalanche activity has been reported.On Friday, numerous size 1.5-2 wind slab avalanches were skier triggered. All of which were from 35-40 degree slopes on NE aspects above 2100 m. All of these avalanches failed within the recent storm snow interface approximately 30 cm down, and on the early April interface around 80 cm down. One of these was remotely triggered from 15 m away, size 2.

Snowpack Summary

Up to 20 cm of new snow overlies a variety of old snow surfaces. These consist of melt-freeze crusts, buried surface hoar and surface facets. Touchy wind slabs exist on lee slopes and behind terrain features. Cornices on ridgelines or huge, and will likely become weak with daytime warming. They pose a threat to slopes below. Surface snow will likely become wet and deteriorate on solar aspects.Deeper in the snowpack a weak interface buried in early April is down about 60-120 cm and consists of a crust and surface hoar. Earlier this week, very large avalanches were reactive on this interface in neighboring regions. The bond may be getting stronger, but I would still use caution and be suspicious of large, steep upper elevation slopes.

Regions covered