Avalanche Forecast

Issued: Jan 18th, 2012 10:05AM

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

pgoddard, Avalanche Canada

South Rockies.

Summary

Confidence

-1 - -1

Weather Forecast

Thursday: A mix of sun and cloud, with a few afternoon flurries. High near -17.Friday: Cloudy with morning sunny breaks, 70% chance of afternoon flurries. High near -12. Snow and trending milder Friday night, light to moderate accumulation. Saturday: Periods of snow, moderate accumulation. High near -5.

Avalanche Summary

A widespread natural avalanche cycle occurred in the Elk Valley on Tuesday/ Tuesday night, with numerous slabs up to size 3 releasing in the alpine on mainly east-facing slopes. Initial reports suggest that these released up to 2m deep on wind-loaded slopes. South of the Crowsnest, a few size 1-2 slabs were reported.

Snowpack Summary

Storm snow totals average around 40cm, with local variability. Cold temperatures have limited storm slab development, however numerous slabs did release during peak loading during the storm. In many areas, fast-moving sluffs remain a key concern. Besides new storm/wind-related concerns, the main layer we're watching in the region is a surface hoar layer buried in early December. It's down about 1m in the Flathead and recently exhibited hard, sudden planar/full propagation results, meaning that it was stubborn to trigger but could create a large avalanche. Facets sandwiched between two firm layers in the top metre of the snowpack are being monitored in the south-east.

Problems

Wind Slabs

Wind slabs have formed mainly on east aspects. Large wind slabs released during the storm. Further avalanches could be triggered by the weight of a person, sled or cornice fall.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 5

Loose Dry

A lot of very dry, loose snow has built up. This has shown the ability to run fast and far, picking up considerable mass as it travels.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

A buried surface hoar layer in the top metre of the snowpack continues to be a concern. Although it has become stubborn to trigger, the consequences are high. It's most likely to be triggered from shallow rocky areas on a slope, or by a large load.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 7

Valid until: Jan 19th, 2012 8:00AM