Avalanche Forecast

Issued: Feb 16th, 2017 4:09PM

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

Avalanche Canada cgarritty, Avalanche Canada

The recent storm delivered a storm slab problem to the alpine while saturating lower elevations with rain. Be aware of increasing hazard as you transition to higher elevations.

Summary

Confidence

Moderate -

Weather Forecast

Friday: Mainly cloudy with isolated flurries and a trace of new snow. Winds light to moderate from the south. Freezing level around 1400 metres with alpine temperatures of -6 in the north of the region, -1 in the south. Saturday: Mainly cloudy with isolated flurries and a trace of new snow in the south of the region. Scattered flurries bringing up to 5 cm to the north. Winds light to moderate from the south. Freezing level around 1000 metres with alpine temperatures of -6 in the north of the region, closer to 0 in the south. Sunday: Mainly cloudy with isolated flurries and a trace of new snow in the north of the region. Scattered flurries bringing up to 5 cm to the south. Winds light to moderate from the south. Freezing level around 1200 metres with alpine temperatures around -6 in the north of the region, closer to 0 in the south.

Avalanche Summary

Observations have been limited during the storm, but loose wet point releases were observes running to Size 2 at lower elevations north of Duffey Lake on Wednesday. A number of (presumably large) natural avalanches were also audible in the Bralorne area on Wednesday.

Snowpack Summary

In the Duffey Lake area 25 cm of snow fell on Tuesday through to Thursday morning. Elevations below 1900 m saw mainly rain. In the south (Coquihalla) we had moderate southerly winds and heavy rain above 1600m on Tuesday night (and rain to 2000m during the day Wednesday). This rain (or snow higher up) landed on either wind slabs in the alpine or temperature crusts at treeline and below, especially on east and south aspects. Both of these surfaces will be good sliding layers for future snowfall. The mid-December facets down 130-160 cm remain a concern especially in shallower snowpack areas in the Duffey, Hurley and/or South Chilcotins. These deeper weaknesses warrant renewed attention after considerable warming and extra loading this week. In southern areas (Coquihalla), the lower snowpack is reportedly well settled and stronger than it is to the north.

Problems

Storm Slabs

An icon showing Storm Slabs
Recently formed storm slabs are expected to remain reactive to human triggering on Friday. Expect hazard to increase along with the depth of new snow as you gain elevation.
Be cautious as you transition into wind affected terrain.Use caution in lee areas in the alpine and treeline. Recent storm snow has formed touchy slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
A persistent weak layer existing mainly in the north of the region is creating a 'low probabity/high consequence' avalanche problem. The recent storm has added a fresh load above this layer, potentially increasing its likelihood of triggering.
Be cautious in shallow snowpack areas where triggering a large avalanche is more likely.Be aware of the potential for very large avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Feb 17th, 2017 2:00PM

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