Avalanche Forecast

Issued: Jan 27th, 2012 3:00PM

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

ghelgeson, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Freezing levels are uncertain on Monday

Weather Forecast

A significant storm system enters the region Saturday evening bringing 30 - 40 cm of new snow. This system exits the region Sunday as freezing levels climb to 1300 m. Average seasonal temperatures return Monday while a weak ridge of high pressure builds into the forecast area.

Avalanche Summary

Several skier triggered size 1 avalanches were reported yesterday as new snow was blown into soft slabs by strong NW winds. A natural cycle driven by the winds was reported from a few different locations. Avalanches from size 1 - 3 were reported.

Snowpack Summary

60 - 100 cm of storm snow has fallen in the last week across the province. While storm shears have been quick to heal, winds have had a dramatic effect on wind exposed terrain at all elevation bands. Soft slabs of 10 - 30 cm were reported Thursday as winds switched to the NW and blew at moderate to strong values.All the new snow is sitting on cold dry snow formed during last week's Arctic Outbreak. The cold dry air created a layer of facets that are being referred to as the Jan 20th, facets. A Rutschblock test in the north showed a result of RB6, MB down 90 on this layer. In the south a CTE test produced a failure down 70 at this interface.The January 13th SH/FC layer is spotty in distribution, but it is still capable of performing. Deep in the pack the mid December layer is gaining strength, but may still be an issue in areas of thin shallow snowpack.

Problems

Wind Slabs

Wind effect has been described as "Extensive, Strong & Intense." Winds out of the W, SW & NW have affected all aspects. The most prevalent wind slab is 10 -30 cm deep and is reactive to human triggers, especially in unsupported / convex terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Cornices

Big winds have created large cornices. Give these behemoths a wide berth whether traveling near them or far below them. Failing cornices have the potential to trigger large avalanches.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

2 - 6

Storm Slabs

The storm snow is settling out and tightening up, but is still reactive to large loads; Cornice Failure, Airborne sled, etc. Wind slab avalanches could step down and trigger a deeper storm slab avalanche.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Valid until: Jan 28th, 2012 8:00AM