Archived

Avalanche Forecast

Feb 19th, 2018–Feb 20th, 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

2: Moderate

The avalanche danger rating in the alpine will be moderate

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

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Coast.

Triggering an avalanche remains a concern at all elevations. Be very suspect around wind-affected slopes and convex terrain features.

Confidence

Moderate - Due to the number and quality of field observations

Weather Forecast

TUESDAY: Sunny, light north wind, alpine high temperatures around -10 C.WEDNESDAY: Mix of sun and cloud with isolated flurries, moderate north wind, alpine high temperatures around -7 C. THURSDAY: Mostly sunny, moderate north wind, alpine high temperatures around -5 C.

Avalanche Summary

No new avalanches were reported on Sunday, but whumpfing in flat terrain (a sign of instability) was reported in the North Shore mountains. Storm snow was very reactive on Saturday. There were numerous size 1-2 slab avalanches triggered by skiers on all aspects at treeline and below treeline elevations, including some that were triggered remotely (from a distance).Looking ahead, avalanche activity is most likely in areas that have been loaded by the recent northerly winds, but any steep terrain feature is suspect given the widespread crust sitting beneath the storm snow.

Snowpack Summary

In exposed terrain, strong north winds have scoured north facing slopes and loaded south facing slopes. In sheltered terrain, cold weather is preserving 30-50 cm of low density snow. A hard rain crust that extends into alpine terrain is buried about 40 cm beneath the recent storm snow. Reports suggest the snow has a poor bond to the crust, meaning there's a potential for slab avalanches on any steep or convex terrain feature. Monitor the bond of the snow to this crust closely. There are no significant layers of concern below the crust.

Avalanche Problems

Wind Slabs

Strong northerly winds have formed fresh slabs at higher elevations.

Use ridges or ribs to avoid pockets of wind loaded snow.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Use caution above cliffs and terrain traps where small avalanches may have severe consequences.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Storm Slabs

Triggering a slab above the buried crust remains a possibility at lower elevations.

Use caution above cliffs and terrain traps where small avalanches may have severe consequences.Use caution on open slopes and convex rolls

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2

Cornices

Large cornices have formed along ridgelines. Cornices are inherently unstable, unpredictable, and demand respect.

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.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2