Avalanche Forecast

Issued: Jan 15th, 2012 3:00PM

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

Avalanche Canada mbender, Avalanche Canada

Summary

Confidence

Fair - Due to variable snopack conditionsfor the entire period

Weather Forecast

SUNDAY: Light precipitation with light winds from the west. Temperatures dropping to -15 degrees celsius. MONDAY: Light precipitation with continued cold temperatures. Winds moderate from the west. TUESDAY: Continued light precipitation and cold temperatures.

Avalanche Summary

Recent reports indicate human triggered avalanches to size 1.5 on windslabs in the alpine and at treeline. Explosives testing in the southern portion of the region indicates (size 3.5 on a north aspect at 2700m with 200cm fracture) that avalanches are capable of stepping down to deep basal facets with heavy loads. Cornices have also been failing and could be a heavy trigger for wind and persistent slabs on the slope below.

Snowpack Summary

5-15cm of dry new snow combined with wind has encouraged slab development and cornice growth. This new snow now sits on a variety of surfaces (facets, surface hoar in sheltered areas, wind crust, soft slabs and hard slabs).The mid-December surface hoar/facet persistent weakness, down 40cm on the eastern side of the range and as deep as 150cm on the western side, is generally producing anywhere from easy (where it's shallow) to hard (where it's deeper) test results. But all tests consistently show a high propensity to propagate fractures. Check out this YouTube video posted by the Panorama ski patrol of an ECTP2 down around 40cm on surface hoar: http://www.youtube.com/watch?v=1_NQns2Nuh0. Basal facets remain a concern for human triggering in shallow snowpack alpine areas. When these persistent weaknesses are combined with weak wind slabs, thin trigger points, and other weaknesses within and under the recent storm snow, the result is a highly variable snowpack with the potential for deep slab avalanches, especially from heavy, thin spot, and/or step-down triggers.

Problems

Wind Slabs

An icon showing Wind Slabs
New snow and wind have created new windslabs and buried recently formed ones.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Most concerning on steep, unsupported slopes, in open glades glades.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Susceptible to human triggers particularly from thin spots on slopes with variable snow distribution, heavy impacts, or deep penetration. If triggered, slabs are likely to release across entire bowls producing highly destructive avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Jan 16th, 2012 8:00AM

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