Avalanche Forecast

Issued: Mar 28th, 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, Cornices and Deep Persistent Slabs.

deryl kelly, Parks Canada

Jasper.

We have been able to move through the mountains cautiously this week at all elevations. Making careful terrain choices, and conservative group management, we've had consistently great skiing on low angled/low consequence north aspect slopes.

Summary

Weather Forecast

Mainly cloudy for Wednesday scattered flurries and possibly 5-8cm accumulation through the day and into Thursday. Light SW winds at ridge top forecasted to stay in that range with some gusts. Alpine temperatures warming slightly for highs near -2C.

Snowpack Summary

Creamy and settled surface snow with some wind effect in the open. Near surface non-persistent weaknesses, active on typically problematic features like convexities and immediate lees. Interfaces dwn between 60 and 100cms though the mid-pack with inconsistent mod to hard field test results. All this, sitting on a large, facet layer off the ground.

Avalanche Summary

New snow transport continuing to over-load cornices and immediate lee features making them susceptible to natural triggering.

Confidence

The weather pattern is stable

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 riding quality.

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

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

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.

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

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

Elevations: Alpine, Treeline.

Likelihood

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Valid until: Mar 29th, 2017 4:00PM