Avalanche Forecast

Issued: Jan 18th, 2014 9:03AM

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

jlammers, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Freezing levels are uncertain on Sunday

Weather Forecast

A ridge of high pressure will continue to dominate the region for the forecast period bringing dry conditions, mainly sunny skies and light winds from the west/northwest. Freezing levels should hover around 1000m for Sunday. Although there's a possibility of an inversion redeveloping for Monday and Tuesday, alpine temperatures are expected to remain just below freezing. No significant precipitation is expected for at least a week.

Avalanche Summary

Steep solar aspects saw numerous loose wet and slab avalanches on Thursday with some occurrences to size 3. On the same day in the south of the region, a snow cat was working on ridge and remotely triggered a size 3 deep slab avalanche from 30m away. The avalanche, which failed on basal facets, occurred on a southeast facing slope at 2160m. Continued point releases to size 1.5 were observed on Friday on steep, sun-exposed slopes.No observations from Saturday's warm-up were available at the time of publishing this bulletin.

Snowpack Summary

Roughly 90cm of well settled storm snow exists as a stubborn wind slab in many exposed areas. Steep, sun exposed slopes are seeing a daily melt-freeze cycle while surface hoar has been growing in some shaded terrain. Below the recently formed storm slab you may find surface hoar buried around January 8th. This interface seems to have become less of a concern for most operations, and is showing mainly moderate to hard resistant planar results in snowpack tests.There are 2 other layers of note which professionals are keeping a close eye on: The late-November persistent weak layer consists of a sun crust on steep south facing slopes and surface hoar in sheltered areas and may sit well over 200cm below the surface. At the base of the snowpack you may also find the October persistent weak layer which consists of facets sitting on a crust. This layer is predominantly found on northerly aspects at tree line and in the alpine. The depth of both these layers makes skier triggering unlikely (maybe a heavy load on a thin spot in steep terrain, a cornice fall or rapid temperature change). The consequences of triggering any of these weaknesses would be severe.

Problems

Deep Persistent Slabs

Although deep persistent slab avalanches may become less likely over the next few day, the consequences of a release would be severe. Possible triggers include cornice fall, rapid temperature changes or a heavy load over a thin spot.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Wind Slabs

Some operators are still expressing concern for wind slabs that were formed last week. Although they may have gained considerable strength, triggering may still be possible in steep, unsupported terrain.

Be cautious as you transition into wind affected terrain.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Jan 19th, 2014 2:00PM