Avalanche Forecast

Issued: Dec 23rd, 2011 8:50AM

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

Avalanche Canada jlammers, Avalanche Canada

Summary

Confidence

Fair - Intensity of incoming weather is uncertainfor the entire period

Weather Forecast

Saturday: 5cm of snow - strong southwest winds - freezing level at 1200mSunday: 20cm of snow - moderate southerly winds - freezinglevel at 800mMonday: 10-20cm of snow - moderate southwest winds - freezing level at surface

Avalanche Summary

Recent observations are limited to isolated human-triggered Size 1 fresh wind slabs. One was 20m wide by 20cm deep on a NE facing alpine slope.

Snowpack Summary

Alpine areas are wind-hammered with scoured and pressed surfaces, exposed crusts, and pockets of hard and soft wind slabs. Buried surface hoar and/or facets may persist 10-20cm below a weak rain crust on sheltered treeline slopes and below. Recent compression tests on a treeline slope produced easy to moderate sudden collapse results down 65cm on on this weakness where it was wind-loaded. Watch this layer as it gets more load and a thick cohesive slab develops, particularly below treeline where the buried surface hoar would be especially large. A strong mid pack overlies weak basal facets and depth hoar in shallow alpine areas. This deep persistent weakness may also deserve attention with more load.

Problems

Wind Slabs

An icon showing Wind Slabs
Fresh windslabs exist below ridge crests, behind lee terrain features and in cross-loaded gullies. Windslab size and reactivity will increase with forecast weather.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Dec 24th, 2011 8:00AM