Avalanche Forecast

Issued: Mar 23rd, 2012 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.

Avalanche Canada pmarshall, Avalanche Canada

Strong solar radiation and mild temperatures this weekend will result in elevated avalanche danger during the day, particularly on sun-exposed slopes.

Summary

Confidence

Fair

Weather Forecast

A ridge of high pressure should maintain sunny and dry conditions for Saturday and Sunday. Freezing levels should rise to 1500m on Saturday and 1600-1800m on Sunday, with cool temperatures overnight. Winds are generally light from the south. A weak system could bring light to moderate precipitation on Monday, but the timing and strength of this system is still a little uncertain. The freezing level should drop to around 1200m as the system approaches.

Avalanche Summary

Recent avalanche activity includes skier and explosive controlled avalanches to Size 1.5 from exposed wind-loaded features. The average depth was around 15-30cm. There were also several cornice failures reported but most did not trigger slabs below.

Snowpack Summary

Solar aspects are likely going through a melt-freeze cycle with frozen snow overnight becoming moist through the day. Snow and wind created fresh wind slabs and storm slabs on Tuesday. Heavy snow which fell last week is settling rapidly and gaining strength. Cornices are large and threaten slopes below. A persistent weakness, formed in mid-February, continues to produce hard, sudden planar results in snowpack tests. The likelihood of triggering this layer has gone down, but very large avalanches remain possible, which could be triggered by a shallower avalanche or cornice fall. The snowpack depth at treeline is 350-500cm.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs lurk below ridges, behind terrain features and in gullies. They may be buried by new snow, making them hard to spot.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Loose Wet

An icon showing Loose Wet
Loose wet avalanches are likely on steep sun-exposed slopes during the day. There is potential for these heavy wet slides to step down to deeper weaknesses and create a large slab avalanche.

Aspects: North, North East, East, South East.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Persistent weaknesses still have the potential to create very large, destructive avalanches if triggered. Possible triggering mechanisms include a person/sled on a thin snowpack spot, cornice fall, or step-down avalanche.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 8

Valid until: Mar 24th, 2012 9:00AM