Avalanche Forecast

Issued: Feb 19th, 2016 8:25AM

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

Avalanche Canada swerner, Avalanche Canada

Storm slabs are expected to remain reactive through the weekend, especially on solar slopes if the sun comes out or on wind loaded slopes in the alpine.

Summary

Confidence

Moderate - Track of incoming weather systems is uncertain on Sunday

Weather Forecast

The last in the series of storms fizzles out Saturday morning. Unsettled conditions will continue through Saturday bringing mostly cloudy skies with some clearing later in the day. Alpine temperatures near -6 with freezing levels falling to 1000m. Ridgetop winds will blow light from the southwest. Sunday morning could see strong outflow winds along coastal inlets with the next Pacific frontal system rolling in by the evening. This could bring anywhere from 5-15 cm, accompanied by strong southerly winds and freezing levels near 1100m. Monday will remain unsettled with cloudy skies and flurries.

Avalanche Summary

On Thursday, a skier remotely triggered a size 1.5 wind slab from a gully feature on an easterly aspect at 2300m. Explosives control showed numerous size 2 storm slab releases from 1900-2300m. Storm slab avalanches are expected to be remain reactive to human-triggering with ongoing snowfall and wind, especially if the sun pokes out on Saturday. Cornices are reported to large and fragile, and may fail under the weight of a person.

Snowpack Summary

Recent storm accumulations are 50-80cm over the past week. This snow overlies a thick rain crust which extends into the alpine. The snow is reported to be bonding well to the crust and all the recent avalanches have been failing within the recent storm snow, not on the crust interface. At treeline and below, other crusts may exist in the upper snowpack due to the recently fluctuating freezing levels. As the freezing level continues to drop, a crust is expected to form at lower elevations. Ongoing southeast through southwest winds have been loading leeward features in the alpine and large cornice development has been reported over the last few days. The weak surface hoar layer from early January can be found down over a meter and is still reactive in isolated snowpack tests but triggering an avalanche on this layer has become unlikely. 

Problems

Storm Slabs

An icon showing Storm Slabs
Recently formed storm slabs are expected to be reactive to rider triggering on Saturday. Extra caution to wind loaded features in the alpine.
The new snow will require time to settle and stabilize. >Choose conservative lines and watch for clues of instability.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Cornices

An icon showing Cornices
Looming cornices could collapse, especially during warm weather and sunshine. The weight of a person may be enough to cause a cornice failure.
Give cornices a wide berth when travelling on or below ridges.>Pay attention to overhead hazards like cornices.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Feb 20th, 2016 2:00PM

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