Archived

Avalanche Forecast

Feb 15th, 2018–Feb 16th, 2018

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

4: High

The avalanche danger rating below treeline will be high

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: South Coast.

New snow sits above a hard crust. Be careful around terrain traps such as cliffs, trees, or gullies where a small avalanche could have severe consequences.

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

FRIDAY: 5-10 cm of new snow by the morning then clearing throughout the day, moderate west wind, freezing level climbing to 900 m with alpine high temperatures around -2 C.SATURDAY: Heavy snow starting Friday night with 30-40 cm possible by the end of the day, strong southwest wind, freezing level around 800 m with alpine high temperatures around -2 C. SUNDAY: Some isolated flurries with clearing throughout the day, strong northeast wind, freezing level dropping with alpine high temperatures around -6 C.

Avalanche Summary

Storm snow was reactive above the crust on Wednesday. Numerous size 1-2 skier and naturally triggered slabs were reported on various aspects at treeline. See here for an example. A cornice collapse was the likely cause of a size 2 avalanche on a north facing slope near the West Lion last weekend. See here for images and more details. Given the poor bond between the new snow and the crust, expect storm slabs to remain reactive for the next few days.

Snowpack Summary

Storm snow is accumulating above a hard rain crust that extends into alpine terrain. By Friday afternoon there could be 30 cm of snow above the crust, enough to make reactive slabs in steep terrain. Deeper wind deposits are likely in alpine terrain. The average snow depth at treeline is 300 cm, with no layers of concern in the lower snowpack.

Avalanche Problems

Storm Slabs

By Friday afternoon up to 30 cm of snow may sit above a widespread crust, potentially forming reactive slabs on steep terrain features.

Choose well supported terrain without convexities.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.Minimize exposure during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Cornices

Large cornices have formed along ridgelines. Cornices are inherently unstable, unpredictable, and demand respect. Give them a wide berth from above and below.

Firm cornices may pull back into flat terrain at ridgetop if they fail.Give cornices a wide berth when traveling on or below ridges.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2