Avalanche Forecast

Issued: Mar 19th, 2013 10:01AM

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

Avalanche Canada pgoddard, Avalanche Canada

Variable snowfall amounts are expected on Wednesday. Correspondingly, there may be quite a lot of local variation in avalanche danger.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain for the entire period

Weather Forecast

Wednesday: Moderate to heavy snow (15-25 cm, mostly in the west). Strong SW winds. Alpine temperature near -4.Thursday: Light snow. Moderate W winds. Alpine temperature near -14.Friday: Light snow. Light winds. Alpine temperature near -12.

Avalanche Summary

On Monday, skiers triggered several small soft slabs and sluffs on wind-loaded or steep terrain. Explosives testing triggered three large (size 2-3) slabs within the storm snow. On Sunday, a natural cycle to size 2.5 was observed in the Bugaboos on a variety of aspects in the alpine.

Snowpack Summary

Forecast storm snow is expected to create new slabs. Recent storm snow was shifted into reactive slabs by strong SW-NE winds on Monday. In some areas, the new snow was sluffing fast and far. Deep storm slabs which formed last week are slowly gaining strength. Cornices are large. A weak layer of surface hoar and/or a crust sits about 50-120 cm below the surface. It’s of most concern at alpine and treeline elevations and exhibits variable results in snowpack tests. At low elevations, a supportive crust above this layer means it's difficult to trigger. This layer may linger with ‘low probability/ high consequence’ type character. Testing for this interface in your local area should help you gain (or lose) confidence before committing to aggressive terrain. A facet/crust layer sits at the base of the snowpack in some places.

Problems

Storm Slabs

An icon showing Storm Slabs
New storm slabs are likely to develop during Wednesday’s storm. Lee loaded slopes may be particularly touchy.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be cautious of sluffing in steep terrain.>Avoid steep slopes below cornices.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 6

Persistent Slabs

An icon showing Persistent Slabs
Storm snow, wind loading or cornice fall may overload a persistent weakness buried in the upper snowpack. This could lead to surprisingly large avalanches.
Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 7

Valid until: Mar 20th, 2013 2:00PM

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