Avalanche Forecast South Columbia

Wednesday 6th February 2019

Avalanche Danger Ratings Wed 6th Feb 4:53PM Danger Ratings Alpine: Moderate Danger Ratings Treeline: Considerable Danger Ratings Below Treeline: Considerable Persistent Slabs Persistent Slabs Wind Slabs Wind Slabs

Avalanche Canada Forecaster: mbender

Date Issued:

Valid Until:

There is a potential for triggering large avalanches at lower elevations due to the presence of a buried weak layer that exists mainly at treeline and below.

Confidence

High - The weather pattern is stable

Weather Forecast

THURSDAY - Mainly cloudy with light flurries, accumulation 5 cm / light southwest winds / alpine high temperature near -15FRIDAY - A mix of sun, cloud and scattered flurries / light east wind / alpine high temperature near -17SATURDAY - A mix of sun and cloud / moderate northeast wind / alpine high temperature near -20

Avalanche Summary

A persistent weak layer that was buried in mid January continues to be reactive to human triggers. This layer is sensitive enough for avalanches to trigger remotely (from a distance). Human triggered avalanches up to size 2.5 were reported on both Sunday, Monday and Tuesday. This MIN report of an avalanche in the Slocan area on Sunday illustrates the continued reactivity of the mid January layer.Widespread avalanche activity was reported on Friday and Saturday. Numerous natural and explosives triggered avalanches to size 3, and human triggered avalanches to size 2 were reported. Many of these avalanches were triggered remotely (from a distance) and failed on the mid January layer.

Snowpack Summary

20-70 cm of recent new snow sits on wind slab, surface hoar (feathery crystals), facets (sugary snow) and a crust on sun-exposed slopes. In many areas, recent winds have formed wind slabs on all aspects due to shifting wind directions. The most notable feature in the snowpack at this time is a persistent weak layer that was buried in mid January, which is now buried 40-90cm. This layer consists primarily of surface hoar, however there is also a crust associated with it on sun-exposed slopes. This layer is the most prominent at treeline and below, and continues to produce avalanches.

Persistent Slabs Persistent Slabs

Likelihood

Likely - Possible

Expected Size

1.5 - 3

40-90 cm of snow sits above a weak layer of surface hoar (feathery crystals) and crust. This layer continues to be reactive to human triggers.

Choose low angled terrain.Any steep opening in the trees should be treated as suspect right now.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

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Wind Slabs Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

20-70 cm of recent snow has been redistributed by north and east winds.

If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: South East, South, South West, West.

Elevations: Alpine.

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