Avalanche Forecast

Issued: Mar 7th, 2013 8:04AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is low. Known problems include Storm Slabs, Persistent Slabs and Cornices.

jon schleiss, Parks Canada

Glacier.

The Feb 12 Surface Hoar is a concern where it has not been triggered during the recent storm cycle. Use caution if you are venturing into undisturbed terrain. The forecast sunny conditions will bring on some avalanche activity in the next few days.

Summary

Weather Forecast

Cloud and light flurries will end this morning, followed by a ridge of high pressure and sunny skies. The freezing level will rise to 1200m today and Friday while dropping to the surface overnight. A weak storm is forecast to arrive on Sunday.

Snowpack Summary

Last weeks' storm snow has settled out rapidly over the past two days. Below treeline, a rain crust and substantial tree bombs have created treacherous travel in some places. In the alpine, soft slabs overly the Feb 12th PWL, now down over a meter which has been reactive to skiers, especially on solar aspects. Wide propagations are still possible.

Avalanche Summary

Natural avalanche activity has decreased however large avalanches are still possible. We are entering a period of "low probability, high consequence" avalanche behavior, in which the likelihood of triggering is less than it was during the storm, but the chance that a skier can trigger a very large avalanche is still very possible. See photo:

Confidence

Problems

Storm Slabs

The storm slab has settled considerably over the past 2 days, but remains a concern due to the potential for wide propagations and step-down to the Feb 12 PWL. Solar aspects and lee pockets are of particular concern.

Be cautious as you transition into wind affected terrain.Use caution in lee areas in the alpine. Recent wind loading have created wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Persistent Slabs

The Feb 12 PWL continues to be a concern. During the last storm cycle several avalanches "stepped" down to this layer. It will remain a problem for some time.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Cornices

Cornices have grown very large and unsupported. They are increasingly likely to fail, providing a trigger for large avalanches. Northerly winds have created reverse loading in some areas.

Extra caution needed around cornices with current conditions.Pay attention to overhead hazards like cornices.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 8th, 2013 8:00AM