Avalanche Forecast

Issued: Apr 8th, 2014 9:05AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Deep Persistent Slabs and Cornices.

Avalanche Canada triley, Avalanche Canada

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Overnight and Wednesday: A mix of snow, rain, and strong Southwest winds is expected overnight as a cold front moves across the region. The freezing level will drop from 2800 metres down to 1500 metres during the light precipitation. Mostly clear skies during the day with light winds and freezing level rising to 2000 metres.Thursday: Mostly sunny with light winds and freezing levels rising to 2300 metres.Friday: Overcast with moderate Southwest winds and light precipitation starting in the afternoon.

Avalanche Summary

A size 3.0 avalanche in the Harvey pass area was reported to have started from a cornice fall and stepped down to the February deep persistent weak layer. Avalanches sliding on this layer are expected to become less likely with the forecast cooler temperatures and lower freezing levels.

Snowpack Summary

Very warm temperatures over the past few days and high freezing levels with no crust recovery have resulted in moist or wet snow at all elevations.In the Smith Basin area there is 140 cm below treeline and the top 40 cm was found to be moist and well consolidated. The March crust below was decomposing at this location. The February deep persistent weak layer was down 80 cm and well preserved. Higher up at about 2300 metres the height of snow was a little over two metres. The March crust was not intact at this location and did not result in any shears in snow profile tests. The February deep persistent weak layer (DPWL) was down 100 cm and was a well defined layer of softer facetted snow below the hard (pencil) snow of the well settled mid-pack. Hard sudden collapse shears were recorded at the interface of the February DPWL. In the Elk Valley South the height of snow at 1900 metres was 430 cm. The snow was dry and loose above 1700-1800 metres and moist below where loose wet slides had released on solar aspects. There was a 2-3 cm supportive crust on Southerly aspects above 1900 metres, and no crust on shaded North aspects.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Forecast lower freezing levels and overnight surface freezing should reduce the likelihood of triggering the deeply buried persistent weak layer.
Consider the consequences of the terrain if an avalanche steps down to a persistent weakness.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Cornices

An icon showing Cornices
Forecast overnight cooling and dropping freezing levels should help to strengthen cornices by morning. Day time warming may weaken cornices in the afternoon.
Do not travel on slopes that are exposed to cornices overhead.>Give cornices a wide berth when travelling on or below ridges.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Apr 9th, 2014 2:00PM

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