Avalanche Forecast

Issued: Feb 13th, 2015 8:16AM

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

Avalanche Canada pgoddard, Avalanche Canada

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Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

Temperatures start cooling on Saturday with the passage of a cold front. 10-15 mm precipitation is expected with the front overnight Friday/ Saturday, tapering to flurries on Sunday. The freezing level falls to around 1500 m on Saturday. Monday is dry and cool, with a chance of sun. Winds are moderate NW, easing to light by late Sunday.

Avalanche Summary

Size 1.5 wind slabs and a size 2.5 storm slab were triggered naturally on Thursday. A number of cornice collapses have been reported over the last few days. Loose wet avalanches failed naturally in steep terrain on Wednesday in response to warming. Also on Wednesday, explosives triggered a couple of size 2 slabs, which failed on the late-Jan crust. Human-triggering of the persistent slab remains possible.

Snowpack Summary

New snow may have been shifted into wind slabs on lee features at alpine and treeline elevations. Keep your eyes open for cornices, which may be large and unstable. A week or so of very warm temperatures has affected the snowpack, creating moist surface layers up to around 2000m. At low elevations, the snowpack may now be relatively uniform. The late-Jan crust/surface hoar layer, buried around a metre deep, remains a key concern, as it could still be human-triggered and could produce a destructive avalanche. The mid-January surface hoar is typically down 80-120cm and is unlikely to be triggered, apart from in a thin or rocky snowpack area. The mid-December weak layer is down over 120cm, but has been generally unreactive lately. Basal weaknesses remain in the back of operators' minds.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Persistent slabs are most likely to be triggered from thin snowpack areas, or with large triggers like cornice fall or an avalanche stepping down.
Avoid common trigger spots, including convexities or areas with a thin or variable snowpack.>Avoid steep slopes below cornices.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Storm Slabs

An icon showing Storm Slabs
New snow and wind may create storm slabs and wind slabs. At low elevations or on sun-affected slopes, loose wet avalanches remain possible, especially on steep terrain.
Be cautious as you transition into wind affected terrain.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Feb 14th, 2015 2:00PM

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