Avalanche Forecast

Issued: Mar 27th, 2017 4:00PM

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

deryl kelly, Parks Canada

Jasper.

A Haiku:Deep Persistent Slab.Not very likely to heal.Constantly watchful(so poetry isn't my strength. But, I think you get the idea;)

Summary

Weather Forecast

Mainly cloudy Tuesday with some isolated flurries and little accumulation. Blustery SW winds at ridge top forecasted to hold steady moderate values with strong to extreme gusts (70 km/h). Alpine temperatures forecasted for a high of -5 °C.

Snowpack Summary

Creamy, pressed and settled surface snow with some wind effect in the open. A spattering of previously buried, near surface wind slabs. Two questionable interfaces dwn between 60 and 100cms though the mid-pack. All this, making up the deep persistent slab; spawning from the whole season snowpack sitting on a large, weak facet layer off the ground.

Avalanche Summary

New wind load is triggering deep slabs and cornice triggered slabs on North through West aspects, up to size 3.

Confidence

Problems

Wind Slabs

Building windslab at tree line and above on lee aspects. It's a continuous problem that requires constant attention in order to ensure your safety and/or riding quality.

Minimize overhead exposure during periods of heavy loading from wind.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

The deep persistent slab can be triggered by travelers from shallow or weak locations or naturally from large loads such as cornice failure or windslab avalanches. On Mar 25, skiers triggered a sz 2.5 in a consistently shallow area at tree line.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Avoid paths that have not avalanched recently.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Cornices

Large cornices on ridge top lee features. Their sheer mass is a problem. Recent cornice failures have been generally small (a few tons or so;) but are consistently triggering large deep persistent slab avalanches in alpine terrain.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 28th, 2017 4:00PM