Avalanche Forecast

Issued: Jan 31st, 2016 8:40AM

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

Avalanche Canada triley, Avalanche Canada

Storm slabs are settling and bonding, but the deeply buried  persistent weak layer continues to be a concern for human triggering.

Summary

Confidence

High

Weather Forecast

Freezing levels at or near valley bottoms for the forecast period. Overcast with flurries and light winds overnight. Overcast with light winds and a chance of flurries on Monday. Light winds with some sunny breaks on Tuesday. A system is forecast to move inland from the coast on Wednesday, expect increasing southwest winds, rising freezing levels, and light precipitation.

Avalanche Summary

There were a couple of natural size 2.0 avalanches reported in the Rossland range that happened on Saturday. Some small natural wind slab or storm slab avalanches up to about 20 cm deep were reported on Saturday from the south of the region. On Friday a couple of operations reported natural slab avalanches up to size 2 that were releasing as pockets of wind slab or thin storm slab. Explosives controlled avalanches up to size 2.0 releasing in the storm snow were also reported on Friday. No new reports of any avalanches releasing down to the persistent weak layers.

Snowpack Summary

Most areas in the region had 3-5 cm of new snow on Sunday morning, the outlier was the southern Monashees in the west of the region where they had 26 cm of new snow overnight. The total recent storm slab of 20-30 cm (in most of the region) may be sitting on a layer of surface hoar that was buried on January 27th, or on top of one or two thin freezing rain crusts up to about 2100 metres. Some areas report that previous strong winds destroyed this new layer of surface hoar, and may have stripped the old surface back to a hard rain crust before the new storm snow arrived. The persistent weak layer that was buried January 4th is now down 80-120 cm and continues to give sudden planar fractures in snowpack tests in some areas.

Problems

Storm Slabs

An icon showing Storm Slabs
The storm slab may continue to react to human triggers in isolated terrain where it is sitting on a buried surface hoar layer down 20-30 cm. The storm slab has not been reactive where it is bonding to a rain crust.
Be cautious as you transition into wind affected terrain. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
This persistent weak layer is probably now best described as a low probability but high consequence problem. Dig down (80-120 cm) to see if the surface hoar exists in your area.
Dig down to find and test weak layers before committing to a big line. >Be aware of the potential for large avalanches due to the presence of buried surface hoar. >

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Feb 1st, 2016 2:00PM

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