Avalanche forecast

Northwest Inland

Jan 28 – 29, 2015Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

A new storm is expected to impact this region on Thursday and Friday. Current models predict its intensity will be less than the previous storm.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    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
    A combination of new snow and wind is likely to build fresh storm and wind slabs, particularly in exposed lee terrain.

  • 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.

Weather Forecast

Thursday: A storm is expected to bring up to 10 cm new snow with freezing levels around 900 m and ridgetop winds around 60 km/h from the southwest. Friday: A further 10-15 cm new snow is expected. Freezing levels for the most part are expected to stay near valley bottom. Strong ridgetop winds are expected to shift from southwest to northwest. Saturday: Dry. Cold. Winds light or moderate.

Confidence

Fair - Intensity of incoming weather systems is uncertain

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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