Avalanche Forecast

Issued: Jan 27th, 2018 3:00PM

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

Avalanche Canada jsmith, Avalanche Canada

Natural avalanche cycle expected on Sunday. Travel in avalanche terrain is not recommended.

Summary

Confidence

High -

Weather Forecast

SUNDAY: 30-50 cm of new snow(rain below roughly 1500m) / Strong southwesterly ridgetop winds / Freezing level rapidly rising to around 1800m.SUNDAY NIGHT: 15-25 cm of new snow(rain below roughly 1500m)  / Strong southwesterly ridgetop winds / Freezing level around 1800m.MONDAY: 15-25 cm of new snow(rain below roughly 1500m)  / Strong to extreme southwesterly ridgetop winds / Freezing level around 1800m.TUESDAY: 5-10 cm of new snow / Moderate southwesterly ridgetop winds / Freezing level dropping to around 800m.

Avalanche Summary

Throughout this region there has been evidence of a natural avalanche cycle up to size 3 that occurred within the storm snow on Wednesday. More notable are the numerous explosive triggered, very large avalanches up to size 3.5 that where reported near Whistler on Thursday. Two additional explosive triggered 3.5's were reported Friday. These avalanches started in the storm snow and then stepped down to the early January and even the mid-December crusts which resulted in very large avalanches running full path. They occurred on northwesterly aspects below rocky ridgetops between 1950-2200 m. Although these layers are over 200 cm beneath the snow surface, a large trigger such as a falling cornice or a smaller human triggered avalanche could very likely "step-down" to these layers resulting in large and destructive avalanches.

Snowpack Summary

15-20 cm of new snow on Saturday morning brings recent storm totals to around 80-100 cm which continues to be redistributed by strong southeasterly winds which are creating dense storm slabs lurking in lee and cross-loaded features. Impressive cornice growth has also been observed on the lee side of ridgetops. 200-250 cm below the surface you'll find a crust that was buried early January and is present at all elevations. Below this there is another crust which was buried in mid-December. Recent explosive control work has triggered storm slab avalanches that have then "stepped-down" to both of these crusts, resulting in very large avalanches running full path. Although these layers are over 200 cm beneath the snow surface, a large trigger such as a falling cornice or a smaller human triggered avalanche could very likely "step-down" to these layers resulting in very large and destructive avalanches.

Problems

Storm Slabs

An icon showing Storm Slabs
New snow, strong winds, and rising temperatures will create touchy storm slabs reactive to human triggers.
Be aware of the potential for wide propagations due to the presence of hard windslabs.Avoid avalanche terrain during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Large triggers such as a falling cornice or smaller storm slab avalanches may step-down to deeply buried crusts, resulting in large and destructive avalanches running full path.
Be mindful that deep instabilities are still present and have produced recent large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2.5 - 4

Cornices

An icon showing Cornices
Large amounts of recent new snow and high winds are creating rapid cornice growth.
Give cornices a wide berth when travelling on or below ridges.Falling cornices may trigger large avalanches on the slopes below.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1.5 - 2.5

Valid until: Jan 28th, 2018 2:00PM