Avalanche Forecast

Issued: Dec 18th, 2017 5:04PM

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

mbender, Avalanche Canada

South Columbia.

Snow amounts will continue to gradually accumulate over a variety of potential weak layers in the coming days.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain on Wednesday

Weather Forecast

TUESDAY: Mainly cloudy with periods of snow in the afternoon and overnight, accumulations 10-20cm / wind moderate east / alpine temperature -11 WEDNESDAY: Cloudy with sunny breaks and isolated flurries / wind light northeast / alpine temperatures -12 THURSDAY: Mainly cloudy with isolated flurries / wind light to moderate northwest / alpine temperature -8

Avalanche Summary

Recent reports indicate explosives controlled and natural storm snow avalanches to size 2.5 in the alpine and tree line .As snow accumulates and settles in the coming days expect to see an increase in avalanche activity.

Snowpack Summary

The 20-40 cm of new snow accumulating through the weekend now sits on a wide variety of old surfaces including large surface hoar (weak, feather-like crystals), hard crusts formed by sun or wind, and sugary facets. As the snow load builds and slab properties develop, it will be important to monitor how the new snow is bonding to the old surfaces. Most concerning would be areas that have surface hoar sitting on top of a hard crust. A crust which was formed by rain in late November is a major feature in the snowpack and is down approximately 60-80cm at tree line elevations. Snowpack tests suggest the snow above is currently bonding well to it. Snowpack depth decreases rapidly below tree line. Look out for early season hazards such as rocks, stumps, and open creeks.

Problems

Storm Slabs

As the recent new snow settles over the next few days, expect it to become reactive to human triggering where it may be sitting on a layer of feathery surface hoar crystals (sheltered areas at and below tree line or northerly alpine aspects)

Buried surface hoar may be preserved on open slopes and convex rolls at and below tree lineWatch for whumpfing, shooting cracks, or signs of recent natural avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

Recent west and northwest winds have created wind slabs in the lee of terrain features.

Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Dec 19th, 2017 2:00PM