Avalanche forecast

Northwest Inland

Jan 29 – 30, 2015Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Forecast new snow and wind are expected to result in elevated avalanche danger. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Although recent cooling has made persistent slabs less likely, given the reactivity of a weak layer buried around 80 cm during the previous storm, I would strongly recommend factoring this problem in to your decision making.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Forecast new snow and wind may develop a new storm slab that could be touchy to human triggers.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–6
    Deep persistent weaknesses were triggered during the last storm. Large destructive avalanches remain a concern, and may reach the end of their run-outs.

Confidence

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

Weather Forecast

Freezing level down to valley bottoms overnight and remaining below 500 metre for the forecast period. Snow starting Friday morning and continuing during the day resulting in 10-15 cm total by Saturday morning. Moderate Southwest winds during the storm should become light Northerly during the day on Saturday. Another pulse of wind and precipitation is expected on Sunday.

Avalanche Summary

Avalanche activity has diminished since an avalanche cycle up to at least size 3 occurred in this region over the weekend, ending on Tuesday. There were a few close calls during this cycle. On Sunday in the Hankin area, a skier accidentally triggered a size 2.5 avalanche which resulted in a full burial and minor injuries. The avalanche was reported to have occurred on a wind-loaded, north-facing slope. The avalanche initially failed on the January crust/surface hoar combo, and then stepped-down to the November crust and basal facets. On the same day in the Sinclair area, a snowmobile may have been the trigger for a size 3 avalanche. The avalanche had a crown between 1 and 2 metres, and propagated up to 200 metres wide. It occurred on a wind-loaded, north-facing alpine slope and may have failed on the November crust facet combo. On Tuesday 27th, a couple of small skier-triggered avalanches were reported. One occurred on a steep roll over at lower treeline elevation and ran on the mid-January layer. The other was a small section of wind slab that pulled off a ridge line in wind affected terrain.

Snowpack Summary

Moderate to heavy snowfall (with rain at lower elevations) and strong southwest winds have built deep and dense storm slabs. These storm slabs are expected to be most reactive in wind-exposed, upper elevation terrain. Below treeline areas are reported to be rain soaked through much of the snowpack. A rain crust and/or surface hoar layer buried mid-January may be found at variable depths between 60- 100cm below the surface. This persistent weakness has been reactive with recent storm loading. Near the base of the snowpack is the crust-facet combination buried in November. This deep persistent weakness seems to have "woken-up" in some terrain in response to warming and heavy loading from wind and snow.

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