Avalanche Forecast

Issued: Nov 27th, 2017 5:29PM

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

william lawson, Parks Canada

Jasper.

Snow and wind have developed a reactive layer that when triggered has the ability to step down to deeper instabilities. A cautious approach to avalanche terrain is recommended.

Summary

Weather Forecast

A cooler and drier air mass is back over the region under a SW flow. Some flurries, moderate gusting strong (ridge top) winds. Overnight snow flurries with freezing levels to the valley bottom. Alpine lows of -13. Winds moderate SW gusting Strong.

Snowpack Summary

Storm slabs and windslabs have formed over the past 24 hours with wind effected snow specific to exposed lee features - these two problems sit on a recently developed rain crust 30 - 60 deep. A persistent slab between 40cm-150cm thick sits on the Halloween Crust, low in the snowpack. This crust can be found up to 2,700m depending on its location.

Avalanche Summary

Explosive control work on highway 93 produced results to sz 2.5. We observed avalanches releasing from new windslab as well as one deeper slab avalanche releasing on the Halloween crust. Minimal natural avalanche activity was noticed.

Confidence

Problems

Wind Slabs

Sensitive wind slabs building quickly at ridge tops and if triggered, has the potential to step down to the deeper instability.

Avoid avalanche terrain during periods of heavy loading from new snow and wind.Avoid freshly wind loaded features.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

This is a complex problem which is hard to assess and predict. Give yourself a wide margin and make conservative terrain choices. Below treeline this layer is only a concern if you are in a run out zone of a large avalanche path.

Be wary of slopes that did not previously avalanche.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Storm Slabs

Storms slabs continue to be an issues as the recent snow settles. Cooler temperatures over the next few days will help heal this problem.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

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