Avalanche Forecast

Issued: Mar 23rd, 2013 4:00PM

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

garth lemke, Parks Canada

Jasper.

Cornices are large so give them a wide berth. Sun has the potential to increase the afternoon avalanche danger at all elevations particularly on S aspects, sun affected bowls, and gullies. Human triggered avalanches remain possible in isolated areas.

Summary

Weather Forecast

Strong diurnal temperature fluctuations will continue to occur. Sunday should stay relatively cool, sun with afternoon clouds, and light N winds. Freezing level should reach 1000m by the afternoon. Monday through Wednesday should be clear skies with a solid freeze occurring at night. Freezing levels are rising to 1600m by late afternoon.

Snowpack Summary

A variable thick slab exists in alpine and treeline locations on a variety of aspects. It is over a strong midpack except in shallow locations where you could trigger basal facets or depth hoar weakness at the ground. At treeline in south facing terrain, their is a suncrust 80 cm deep. Strong diurnal temperature fluctuations have helped stability.Â

Avalanche Summary

Nothing new noted on Saturday's Icefield's patrol with good visibility. A size 3 was observed Friday off Indian ridge main peak up Whistler creek. It scrubbed to ground and ran far. Thursday in Shangrila a size 3 occurred. It was triggered by cornice fall in the afternoon heat, scrubbed to ground, 2m crown, and ran full path.

Confidence

Timing or intensity of solar radiation is uncertain

Problems

Deep Persistent Slabs

Last week's 90cm of snow has generally bonded with the snowpack. North and South winds produced a thick slab on a variety of aspects overlying weak basal facets. Cornice failures can trigger this in a big way.

Avoid shallow snowpack areas where triggering is more likely.Plan to be off big slopes before the temperatures rises and the snowpack deteriorates.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Mar 24th, 2013 4:00PM