Avalanche Forecast

Issued: Feb 12th, 2018 5:32PM

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

Avalanche Canada cgarritty, Avalanche Canada

Maintain elevated caution around areas where wind loading has occurred. Small avalanches can have big consequences around cliffs and other terrain traps.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Tuesday: Cloudy with flurries beginning late in the day and bringing 10-15 cm of new snow by Wednesday morning. Moderate to strong southwest winds. Freezing level dropping to 500 metres as the temperature inversion breaks down. Alpine high temperatures of -4.Wednesday: A mix of sun and cloud. Light north winds. Freezing level to 700 metres with alpine high temperatures of -2.Thursday: Mainly cloudy with flurries increasing over the day and bringing approximately 15 cm of new snow by Friday morning. Light southwest winds increasing over the day and overnight. Freezing level to 600 metres with alpine temperatures of -3.

Avalanche Summary

On Saturday, a cornice collapse was the likely cause of a size 2 avalanche on a north facing slope near the West Lion. See here for images and more details. Pockets of thin wind slab may exist in wind-loaded areas in the high alpine and may be sensitive to human triggers.

Snowpack Summary

Rain at the end of the week saturated snow surfaces and only higher alpine elevations were lucky enough to receive a light cover of new snow. With the arrival of cold temperatures, the upper snowpack has locked up as a firm crust. Where new snow exists above the crust, it has been redistributed by recent strong southwest winds. The average snowpack depth at treeline is 300 cm of well settled snow with no significant layers of concern.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs may have a poor bond to the underlying crust and be reactive at upper alpine elevations. Recent shifting winds may have formed new slabs on a wide range of aspects. Loose dry avalanches are possible from steep alpine terrain features.
Use caution above cliffs where small avalanches may have severe consequences.Be careful with wind loaded pockets that may exist near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Cornices

An icon showing Cornices
Large cornices have formed and may remain fragile. Cornices are inherently unstable, unpredictable, and demand respect. Give them a wide berth from above and below.
Give cornices a wide berth when traveling on or below ridges.Firm cornices may pull back into flat terrain at ridgetop if they fail.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Feb 13th, 2018 2:00PM