Avalanche Forecast

Issued: Apr 15th, 2017 4:09PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Cornices, Wind Slabs and Loose Wet.

jsmith, Avalanche Canada

North Columbia.

Falling cornices continue to trigger large avalanches. Solar radiation and rapidly rising freezing levels make this a very real possibility on Sunday.

Summary

Confidence

High -

Weather Forecast

SUNDAY: Sunny. Light southwesterly ridgetop winds. Freezing level RAPIDLY RISING to 1900 m.MONDAY: Mix of sun and cloud with isolated flurries. Light southwesterly ridgetop winds. Freezing level around 1800m.TUESDAY: Cloudy with flurries. Light southerly ridgetop winds. Freezing level around 1900m.

Avalanche Summary

Several cornice triggered deep persistent slab avalanches failing on facets deep in the snowpack were reported on north aspects in the alpine on Friday. One size 3.5 at Rogers Pass and two north of Revelstoke (size 2-2.5). The key weather factor to keep your eye on this weekend will be the sunshine accompanied by rising freezing levels. These are common trigger for cornices which is currently our primary concern due to their ability to trigger large avalanches.

Snowpack Summary

Cornices are large, looming, and the primary concern due to their potential to trigger large avalanches failing on facets at the bottom of the snowpack. Convective showers and moderate southwesterly winds have formed small wind slabs on lee features below ridgetops. Solar radiation is a common trigger for loose wet avalanching in steep terrain, especially when new snow gets heated by the sun for the first time.

Problems

Cornices

Minimize exposure to slopes with large cornices overhead when it is cool and cloudy and completely avoid them if it is warm and/or sunny.

Cornice failures could trigger large avalanches.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Convective flurries and moderate southwesterly winds have created wind slabs in lee features at treeline and above that were reactive to human triggers on Saturday.

Be cautious with wind loaded pockets near ridge crests and roll-overs.Use ridges or ribs to avoid pockets of wind loaded snow.Keep an eye out for reverse loading created by shifting winds.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Loose Wet

Small loose wet avalanches have the potential to trigger large avalanches on sugary facets near the bottom of the snowpack.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.Solar radiation is a common trigger, especially where new snow is sitting on a crust.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Apr 16th, 2017 2:00PM