Avalanche Forecast

Issued: Mar 26th, 2016 8:36AM

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

Avalanche Canada pmarshall, Avalanche Canada

Triggering lingering storm slabs and fresh wind slabs is possible on Sunday, mainly from steep, north-facing alpine terrain. 

Summary

Confidence

High

Weather Forecast

SUNDAY: Periods of snow – around 10 cm. The freezing level is around 1400-1500 m. Winds are moderate from the W-SW. MONDAY: A mix of sun and cloud. The freezing level climbs to 1800-2000 m and winds ease to light. TUESDAY: Mainly sunny. The freezing level is around 2000 m and winds are light.

Avalanche Summary

On Friday there was one report of a very large (size 4) persistent slab on a large south-facing slope that was triggered by new snow loading. This avalanche likely failed on the late February interface. There were also numerous reports of natural storm slabs up to size 2.5, a few natural cornice falls, and several skier triggered slabs up to size 1.5. The majority of recent avalanches occurred on northerly aspects, but there were a few on south-facing alpine slopes as well.

Snowpack Summary

New storm slabs have developed above a mix of surfaces, including crusts on solar aspects, moist snow up to treeline, and dry snow or recent wind slabs in the alpine on shaded aspects. Cornices continue to be described as large and fragile. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60 to 110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. New storm loading above the buried persistent weak layer may increase the likelihood of triggering large avalanches. Expect loose wet avalanches and natural cornice falls during periods of strong solar radiation and/or daytime warming.

Problems

Storm Slabs

An icon showing Storm Slabs
Fresh storm slabs may be sensitive to rider triggering, especially in steep wind-loaded terrain.
Be alert to conditions that change with elevation.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Cornices

An icon showing Cornices
Cornices are an ongoing concern and should be treated with respect. Failing cornices have potential to trigger stubborn persistent weaknesses.
Extra caution needed around cornices with current conditions.>Do not travel on slopes that are exposed to cornices overhead.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Persistent Slabs

An icon showing Persistent Slabs
The persistent weak layer of buried surface hoar, facets, and crusts is buried down close to a metre. This has become a low probability of triggering, but high consequence of large avalanche problem.
Avoid slopes with glide cracks.>Choose well supported terrain without convexities.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 6

Valid until: Mar 27th, 2016 2:00PM

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