Avalanche Forecast

Issued: Apr 4th, 2013 9:52AM

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

mbender, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Freezing levels are uncertain on Friday

Weather Forecast

Friday: A low pressure system will move over the interior late Thursday through Friday bringing moderate to locally heavy precipitation. Freezing levels will be around 2000m. Winds moderate from the southwest.Saturday: Overcast with light to locally heavy precipitation possible. Winds moderate from the southwest. Freezing level at 2000m.Sunday: A break between off-shore weather systems will bring overcast skies with light amounts of snow and some possible sunny breaks.

Avalanche Summary

Numerous natural loose wet avalanches up to size 2.5 during periods of intense solar radiation.

Snowpack Summary

At upper elevations 10-15cm of new snow is covering a crust or moist snow. In some places in the alpine and at treeline this new snow may have buried a recently formed layer of surface hoar or facets. At lower elevations (below 2000m) rain has made the snow surface wet or moist. New snow combined with wind will has made large cornices even bigger.The March 10th surface hoar/crust interface is buried more than 100cm in most places. Although unlikely to trigger, this deep persistent weakness remains a concern because of the potential for very large avalanches particularly with heavy triggers such as cornice falls or lighter triggers on solar aspects where the crust is more prevalent. Below this the snowpack is strong and well settled.

Problems

Loose Wet

With little re-freezing overnight, loose wet avalanches will run on solar aspects if there is rain falling or even short periods of intense solar radiation. Wet slab avalanches are also possible.

Avoid travelling on slopes which are becoming wet due to rain, warm temperatures, or sun.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Wind Slabs

New snow and wind will have created wind slabs in the lee of terrain features.

Be cautious as you transition into wind affected terrain.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Cornices

Natural cornice falls are a concern during daytime warming. Cornices may also be triggered easily by traveling near them.

Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Apr 5th, 2013 2:00PM