Avalanche Forecast

Issued: Feb 19th, 2014 8:34AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Storm Slabs.

Avalanche Canada triley, Avalanche Canada

Widespread natural avalanche cycle continues. See blogs for more info.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

Overnight and Thursday: Broken skies overnight becoming cloudy in the early morning with convective flurries during the day. Freezing level down to valley bottom overnight and rising briefly up to 1200 metres during the day. Strong Westerly winds.Friday: Cloudy with periods of flurries combined with moderate Northwest winds. Freezing level at valley bottoms.Saturday: Cloudy with sunny breaks and alpine temperatures around -15. Light Northwest winds.

Avalanche Summary

We continue to get reports of accidentally triggered and remote triggered avalanches. There was a size 4.0 natural slab avalanche in the neighbouring Lizard range that ran full path and piled up debris including mature timber in the valley bottom. See the bottom left of the bulletin page for a list of reported avalanches for this region. I suspect that the storm slab is settling and becoming more cohesive. Forecast new snow and wind loading are expected to add a new load to this recent storm slab that may increase the sensitivity to human triggers and may result in natural avalanches.

Snowpack Summary

The recent storm snow slab is now close to a metre thick and continues to settle into a cohesive slab that has become more stiff as it settles (one finger resistance). The layer of weak facetted (four finger resistance) snow that is below the storm slab has been reported as widespread on all aspects and at all elevations across the region. This is the classic firm slab over soft and weak layer that can allow for wide propagations and remote triggering. This problem may persist for days after the storm or even weeks. Forecast new snow and continued strong winds are expected to overload the weakness and cause another natural avalanche cycle. Regardless, it will continue to load above the weak layer priming conditions for large slab avalanches. The mid snowpack is strong and supportive. A deep persistent layer of facets and depth hoar near the base of the snowpack has remained dormant to this point, but may become a concern with additional load and stress on the snowpack.

Problems

Storm Slabs

An icon showing Storm Slabs
A few more cm of new snow and continued strong winds are forecast. Expect natural avalanche activity, long fracture propagations and remote triggering to continue.
The new snow will require several days to settle and stabilize.>Minimize exposure during periods of heavy loading from new snow, wind.>Extra caution needed around cornices with current conditions.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

3 - 6

Valid until: Feb 20th, 2014 2:00PM

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