Avalanche Forecast

Issued: Mar 12th, 2014 9:32AM

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

Avalanche Canada rbuhler, Avalanche Canada

Summary

Confidence

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

Weather Forecast

A frontal system will approach the south coast on Thursday afternoon and should result in precipitation for Thursday night and Friday morning. A second, larger system should reach the south coast early Saturday.Thursday: Increasing cloud cover, snowfall beginning in the late afternoon, freezing levels am: 800m pm: 1500m, ridgetop wind light SWThurs. Night/Friday: Snow 15-20cm, freezing levels am: 1000m pm: 1300m, ridgetop wind 20-30 km/h SWSaturday: Precipitation moderate to heavy, freezing levels am: 500-800m, pm: ~1800m, ridgetop wind 30-40 km/h SW

Avalanche Summary

The weekend saw widespread natural activity.  Isolated activity was reported on Monday.  No new avalanches were reported on Tuesday.

Snowpack Summary

The storm snow from the weekend is reported to be settling rapidly and bonding well with the snow below.  There are two persistent weak layers which remain a concern but the problem is becoming isolated.  The early-March crust/facet layer is down roughly 1m and the early-Feb layer is down 1.5m or more.  These layers are typically deep enough that human-triggering is unlikely but smaller avalanches or cornices have the potential to step down to these layers.  During the avalanche cycle on the weekend we saw avalanches stepping down to these layers and resulting in large, destructive avalanches.  Use caution in thin snowpack areas where triggering a layer could be possible.Strong SW winds during the storm created widespread wind slabs on lee features in the alpine.  These are breaking down and getting harder to trigger but may still pose a threat in some areas.Freezing levels have been cycling between valley bottom and roughly 2000m, and low elevation terrain saw significant rain on the weekend.  The snowpack at lower elevations is generally stable but it may be possible to trigger loose wet activity from steep terrain during the heat of the day.

Problems

Persistent Slabs

An icon showing Persistent Slabs
There are a couple of persistent weak layers within the snowpack.  While generally well bonded, the layer can still produce avalanches in isolated areas.  Use extra caution in thin areas and on steep, unsupported features, especially on north aspects
Be aware of the potential for large, deep avalanches.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Wind Slabs

An icon showing Wind Slabs
Strong SW wind resulted in widespread wind slab formation in the alpine.  These are likely become more stubborn to trigger but still pose a threat, especially on steep, unsupported features.
Avoid steep lee and cross-loaded features - typically exposed North and East facing slopes.>Be cautious as you transition into wind affected terrain.>

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Mar 13th, 2014 2:00PM