Avalanche Forecast

Issued: Dec 30th, 2013 9:13AM

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

jfloyer, Avalanche Canada

South Columbia.

Summary

Confidence

Good

Weather Forecast

Tuesday: Dry, mostly cloudy with some sunny breaks. Treeline temperature around -3C. Ridgetop winds aronud 35 km/h from the W or NW.Wednesday: Dry, cloudy with some sunny periods. Temperatures starting cold but rising to around -3C in the afternoon. Winds around 30 km/h from the NW.Thursday: Precipitation becoming steadily heavier through the day. 5-10 cm expected. Temperatures rising in the afternoon to around -1C. SW winds up to 80 km/h.

Avalanche Summary

A few slab and loose avalanches to size 1.5 have been reported in the last 2-3 days. These are isolated to the most recent storm snow.

Snowpack Summary

Recent moderate to strong southwesterly and northwesterly winds continue to build wind slabs on exposed alpine and treeline slopes. 30-50 cm of recent storm snow sits on a weak layer consisting of surface hoar crystals, stellar crystals and/or crust. Around 60-90 cm below the snow surface, the early December surface hoar, facetted snow, and/or a crust interface sits and is reportedly still variably reactive in snowpack tests.The late-November persistent weak layer consists of a sun crust on steep south facing slopes and surface hoar in sheltered areas. It is now buried 80-110cm below the surface. Snowpack tests vary on this interface with some results producing "sudden" shears and others producing no results. This interface is generally considered to be dormant. However, professional operators are still keeping a close eye on it.A weak layer of facets sitting on a crust that formed in October, sits near the base of the snowpack. This layer is predominantly found on north-facing alpine slopes with smooth ground cover. Triggering this weakness is unlikely, however if triggered the resulting avalanche would potentially be a large event with high consequences.

Problems

Wind Slabs

New snow combined with moderate to strong southwest and northwest winds have created wind slabs in the lee of terrain features on a variety of aspects.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Buried persistent weak layers exist in the upper 110 cm of the snowpack.

Carefully evaluate and use caution around thin snowpack areas.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>Start on small terrain and slope-cut the top of slopes before riding them.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Dec 31st, 2013 2:00PM