Avalanche Forecast

Issued: Dec 22nd, 2017 8:05AM

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

mark herbison, Parks Canada

Glacier.

A surface hoar layer is buried by 40cm of settling snow and could become increasingly reactive. Take the time to evaluate the snowpack as you transition into avalanche terrain, pay attention to cracking and settlements in your surrounding area.

Summary

Weather Forecast

A ridge of high pressure will build throughout the day bringing sun but no snow. The winds will be from the North in the15-40km/hr range with an Alpine high of -17... bbrrr thats cold!! The clear skies and cold temps will continue over the weekend and into early next week. No snow in the forecast.

Snowpack Summary

50cm of settling snow sits on the Dec 15 surface hoar, persistent weak layer. On steeper solar aspects this layer is a crust and/or a crust with small surface hoar on top. The crust runs up into the alpine on steep south and west aspects. Deeper in the snowpack there are a series of crust layers that are currently bonding well.

Avalanche Summary

Numerous natural avalanches over the past few days up to sz 2.5 from steep terrain. The surface hoar layer at tree line and below will become increasingly reactive as the storm snow settles into more of a cohesive slab. Be aware of this when traveling in steeper, open areas or where a slab exists.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

Recent storm snow is settling into a persistent slab. Expect the slab to be increasingly sensitivity as you transition into steep and/or wind effected terrain. Solar aspects harbor a thin crust layer below the slab and a facet surface hoar combo BTL.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

20-40km/hr N-NE winds are forming reverse loaded wind slab in wind exposed areas at and above tree line. These slabs may have surface hoar or crust underneath leading them to be sensitive to human triggering.

Watch for signs of instability such as whumpfing, or cracking. Keep an eye out for reverse loading created by N-NE winds.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Dec 23rd, 2017 8:00AM