Avalanche Forecast

Issued: Nov 22nd, 2013 9:09AM

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 Rockies.

Please note this bulletin is based on limited information. If you have been out and have observations, please send them to forecaster@avalanche.ca

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

A ridge of high pressure will dominate the pattern through the period.Saturday: Dry and sunny. A temperature inversion will bring warm alpine temperatures of up to 5C, valleys may be substantially cooler. Winds light northwesterly.Sunday and Monday: Pretty much the same as Saturday, except the strength of the inversion will likely diminish and winds may pick up slightly for Sunday.

Avalanche Summary

Avalanche activity was reported in pockets of deeper snow from Monday (18th) and Tuesday (19th) in both western and eastern areas of the region. Activity appears to have tapered off. Recent slope tests have produced results only in isolated pockets of wind slab on steep convex rolls.

Snowpack Summary

Treeline snowpack depths in sheltered areas vary between approximately 40-80 cm. In the alpine, coverage is highly variable due to recent high winds. A crust or significant density change may exist around 40 cm below the surface. This has been reported to have weak faceted crystals above and below, and produces sudden "pop" results in compression tests. Below this near the base of the snowpack, an earlier crust buried in October lies close to the ground. This layer may still be of concern on isolated smooth terrain features that have not seen avalanche activity.

Problems

Wind Slabs

Fresh wind slab is widespread and likely triggerable on steep, convex slopes near summits and ridgelines.

Use ridges or ribs to avoid pockets of wind loaded snow.>Use caution in lee areas in the alpine. Recent wind loading have created wind slabs.>Avoid freshly wind loaded features.>Avoid freshly wind loaded features.>Use caution in lee areas in the alpine. Recent wind loading have created wind slabs.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

There may be slopes where deeper instabilities may be triggered, especially during forecast warm weather this weekend. The most likely candidates are alpine slopes facing SW to N where no previous avalanche activity has been noted.

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

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Nov 23rd, 2013 2:00PM