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Avalanche Forecast

Archived

Nov 26th, 2012–Nov 27th, 2012

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

Little Yoho.

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

Weather Forecast

Cool  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

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.