Avalanche Forecast

Issued: Nov 30th, 2012 8:49AM

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

Parks Canada Danyelle Magnan, Parks Canada

A warm storm system is forecast. Up to 20cm of heavy snow and loading by SW'ly winds is expected by tomorrow morning. Conditions will change rapidly. Spreading out while crossing paths like Frequent Flyer, and a higher track up Connaught are advised.

Summary

Weather Forecast

Mild and wet SW'ly flow is forecast for the weekend. Expect up to 10cm precip today, 10cm overnight and up to 20cm on Saturday.  Moderate SW winds will load slopes, and warm temps will promote slab formation.

Snowpack Summary

10cm of dense snow has buried a suncrust of steep solar slopes and surface hoar elsewhere. This will form a touchy storm slab with warm temps and loading by moderate SW winds.  Facets are growing around the Nov 6 crust down ~1m which may become reactive with increasing load.

Avalanche Summary

Cheops N4 (aka STS couloir) ran naturally yesterday into the avalanche fan.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Problems

Storm Slabs

An icon showing Storm Slabs
10 cm of storm snow has buried a layer of surface hoar and on southerly aspects a sun crusts. With forecast snow and wind over the weekend, this layer will become a concern. It will be easy to trigger and as the slab develops it may propagate.
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Good group management is essential to manage current conditions safely.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
The Nov 6 crust complex has yet to produce any avalanches. In snowpack tests it takes a hard force but gives a planar result. As the load on this layer increases, it may become reactive. Cornice failures have occurred, and provide a large trigger.
Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.Avoid avalanche terrain during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 1st, 2012 8:00AM