Avalanche Forecast

Issued: Nov 29th, 2011 4:16PM

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

jon stuart-smith, Parks Canada

Waterton Lakes.

Although avalanche danger has fallen from last week, deep instabilities are still present. Travel conditions are challenging. Below 1900m all aspects are covered in crust. Wind slabs are on all lees slopes and any SW aspect has been stripped bare.

Summary

Problems

Wind Slabs

Extreme SW wind over the weekend have created the potential for surface slabs over this heavier midpack. 10cm is forecast for the next 24 hrs with NE winds. Avalanche danger should not increase significantly unless we get more than forecast.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

Numerous slab avalanches occurred during the storm last week, failing on basal crusts and weak layers near the ground. This problem still persists but triggering it seems difficult. However, any avalanche activity on this layer will be destructive.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 2nd, 2011 4:00PM