Avalanche Forecast

Issued: Nov 26th, 2012 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

The right trigger in the right place can produce deep slab releases down to the Nov. Crust or ground. Stick to moderate slope angles and enjoy. JBW

Summary

Weather Forecast

CoolÂ mainly clear weather through Thursday when pacific onshore flow will bring rising freezing levels and some precipitation.

Snowpack Summary

Last week's storm snow has not had much wind effect and in most places is well bonded and low density. A stellar layer down 30-40 and the November 6 crust down 50-80 are the major weak layers responsible for recent avalanches.

Avalanche Summary

A couple of large deep natural avalanches out of steep alpine terrain have been observed that have failed down to near the ground (Mt. Jimmy Simpson, Mt Rundle.) Explosives are also triggering the odd deep slab (Mt. Lipalian) Early season instability

Confidence

Problems

Wind Slabs

20-40 cm thick soft and hard slabs, reactive to explosives and ski cuts and restricted mostly to immediate lee of ridge crests or in open areas Somewhat isolated and stubborn to trigger

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The load on this layer is in the critical range. Open areas at treeline have just enough stiffness in the slab to have the potential for deep triggering and propagation. Several Na, skier and explosive avalanches up to size 2.5 in the last 36 hrs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Nov 27th, 2012 4:00PM