Avalanche Forecast

Issued: Feb 8th, 2017 4:15PM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs, Loose Dry and Persistent Slabs.

mark herbison, Parks Canada

Jasper.

Up to 30cm of snow on Thursday with warming temperatures and strong Southwest winds. Expect natural avalanche activity to increase in size and frequency throughout the day and to continue into the weekend.

Summary

Weather Forecast

Snow arrives Thursday morning and forecasted to be 25-30cm by Thursday night! Temps will rise with the incoming snow with an Alpine high of -5 with the winds also increasing, Strong from the SW. Snow tappers off by Friday morning with temps dropping back to - 12 with moderate SW winds.

Snowpack Summary

Moderate to strong SW winds are building windslab at treeline and above. A buried surface hoar and facet interface is down 10-15 cm which will be one of the layers of concern with the incoming storm. The mid-pack is facetted and weak, with depth hoar at its base.

Avalanche Summary

A highway patrol revealed a 48-72hr old natural avalanche cycle up to Sz 3. Most occurring below ridgeline, cross loaded gullies or within steep rocky terrain on NE to W aspects in the Alpine.

Confidence

Intensity of incoming weather systems is uncertain on Thursday

Problems

Wind Slabs

Strong SW winds building windslab with recent storm snow and expected to bond poorly.

Use caution in lee areas. Recent wind loading have created wind slabs.Keep an eye out for reverse loading created by an upslope storm.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Dry

Forecasted storm snow (~30cm) will fall over a poorly bonded, weak snow pack. Small sluffs have potential to entrain a lot of mass and grow in size quickly.

Sluffs may trigger deeper instabilities.Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

The Jan 17 interface or deeper layers might be woken up with the forecasted heavy snowfall and would result in large avalanches.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Feb 9th, 2017 4:00PM