Avalanche Forecast

Issued: Feb 29th, 2012 9:14AM

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

Avalanche Canada pgoddard, Avalanche Canada

Conditions are highly variable across the region. To safely manage your exposure to avalanche terrain, you'll need the training to accurately assess persistent weaknesses in your local area.

Summary

Confidence

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

Weather Forecast

Thursday: Flurries, accumulating to about 5cm. Light, north-westerly winds. Freezing level valley floor. Friday: Moderate snowfall starting in the afternoon. Freezing level gradually starting to rise. Mainly light, north-westerly winds.Saturday: Snow continuing, with 15-25cm possible. Freezing level rising to around 1400m.

Avalanche Summary

The recent avalanche cycle, which included daily natural, human and remotely-triggered avalanches in the size 1.5-3 range, has slowed with time. While the likelihood of triggering has dropped, the potential consequences remain high due to the presence of persistent weak layers which can propagate widely and be triggered remotely, creating dangerous conditions.

Snowpack Summary

Recent storm snow has become somewhat less reactive above the Feb 16. surface hoar layer and the early Feb. interface, however these layers are still exhibiting sudden planar ("pops") results in snowpack tests. The early Feb. interface consists of surface hoar (observed into the alpine, but most commonly found at and below treeline) and/or a crust (found on solar aspects, and on all aspects below about 1600m). These weaknesses are tricky to manage, as they are still very touchy in certain locations, but the distribution of them is variable, so it's hard to know exactly which slopes are concealing these layers. Local snowpack observations and a suspicious attitude will be required to safely manage these conditions. Old and new wind slabs, which exist on a variety of slopes, could step down to a persistent weakness and create a surprisingly large avalanche. Large cornices loom in some areas. Shallow snowpack areas may still harbour basal facets. The current snow surface is developing spotty surface hoar, surface faceting and sun crusts, which may bond poorly with incoming snow this weekend.

Problems

Wind Slabs

An icon showing Wind Slabs
Old and new wind slabs exist on a variety of slopes. Persistent weak layers are buried beneath these slabs, meaning they could step down and create very large avalanches. Large cornices also threaten many slopes.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 6

Persistent Slabs

An icon showing Persistent Slabs
Several weaknesses in the upper snowpack have become less likely to be triggered, but consequences remain high. In some locations, large, destructive avalanches could be triggered by a light load, even from a distance.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 7

Valid until: Mar 1st, 2012 8:00AM