Avalanche Forecast

Issued: Mar 8th, 2013 8:00AM

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 upper layers of storm snow are sluffing easily in steep terrain. These sluffs can get big enough to push a rider down or even trigger deeper instabilities. Use caution when entering areas that have not avalanched in the last cycle.

Summary

Weather Forecast

Cool and dry in the morning, then warming through the day with little precipitation and freeze lines rising to 1400m. No snow at all this weekend but some hope for a storm bringing snow on Monday morning.

Snowpack Summary

Last weeks storm snow has settled out rapidly over the past four 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

No new avalanches were recorded in Glacier National Park for the last two days.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Storm Slabs

The storm slab has settled considerably over the past 4 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.

The recent snow may now be hiding windslabs that were easily visible before the snow fell.Sluffs may trigger deeper instabilities.

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.Test slopes before committing to them.

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, especially during periods of strong sun or warming, providing a trigger for large avalanches. Northerly winds have created reverse loading in some areas.

Give cornices a wide berth when travelling on or below ridges.Cornices become weak with daytime heating, so travel early on exposed slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 9th, 2013 8:00AM