Avalanche Forecast

Issued: Dec 27th, 2011 9:48AM

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

swerner, Avalanche Canada

South Rockies.

There are limited field observations from this region. If you have information feel free to email forecaster.ca

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Tuesday Overnight: snow amounts up to 15cms. Ridgetop winds up to 100km/hr from the West. Freezing levels at valley bottom. Wednesday: Snow amounts up to 10cms. Ridgetop winds 70-110km/hr from the West, wind warning in effect. Freezing levels could rise to 1600m. Thursday: Snow amounts 5-10cms. Ridgetop winds 55-90km/hr from the West. Freezing levels near 900m. Friday: Snow amounts up to 5cms. Winds still westerly in the moderate ranges. Freezing levels at valley bottom.For more information on zonal weather patterns and timing please visit our new Forecasters Blog Post.

Avalanche Summary

No new avalanches. Nearby (in the Lizard Range) there were 2 incidents reported on December 22 and 1 on December 23. For more information please visit avalanche.ca, click Bulletins then incident report database.

Snowpack Summary

Strong westerly winds continue, creating wind slabs on lee locations and scouring on windward locations in the alpine and open treeline. A buried layer of surface hoar lies approximately 20 cm below the snow surface. This layer is not widespread and reports indicate this layer was blown and destroyed in the alpine, and wind exposed areas at treeline and below. This layer is likely found in isolated, sheltered locations at and below treeline. A well settled mid pack bridges over the basal weaknesses at the ground.

Problems

Wind Slabs

Predominantly north through southeast but cross-loading is also possible on open slopes oriented parallel to the wind, which contain features and gullies to catch wind-drifted snow.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

More of an issue in the north-west of the region where the snowpack is deeper. The mid-December surface hoar layer was destroyed in wind exposed areas. I'd be suspicious of sheltered treeline locations where it may be more preserved.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Dec 28th, 2011 8:00AM