Archived

Avalanche Forecast

Mar 13th, 2016–Mar 14th, 2016

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

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

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: Northwest Inland.

Watch for snow and wind to form fresh thin wind slabs in lee features through the day.

Confidence

Moderate

Weather Forecast

MONDAY: snow starting overnight with 10-15cm expected by the end of the day, light to moderate southwesterly winds, 1000m freezing level. TUESDAY: light to moderate snowfall continues, moderate to strong westerly winds, 800m freezing level. WEDNESDAY: flurries, light and variable winds, 800m freezing level.

Avalanche Summary

On Friday, natural avalanche activity was reported from steep south facing terrain in the alpine north of Smithers. In the northern part of the region there were some reports of solar induced slabs to size 3 on south aspects, and natural cornice falls. One cornice fall triggered a size 4 avalanche that released on the ground and cleaned out an entire bowl. It was 1km wide and ran 1.5km.

Snowpack Summary

Roughly 20-60 cm of snow has fallen in the past week and is now well settled. Moderate to strong winds have formed hard and soft wind slabs in exposed terrain. Moist snow can be found at lower elevations and on slopes that see direct sunlight. In the north of the region several buried weak layers can be found in the upper meter of the snowpack. A more widespread layer of surface hoar from early January can be found in isolated locations between 60 and 140 cm down. There hasn't been any activity reported on this layer for a couple of weeks now and it is becoming less of a concern. In shallower areas the snowpack sits on a weak base layer of facetted snow. Recently, this layer has been active in the north of the region, responsible for several large avalanches in unsupported alpine terrain. Cornices are large and fragile.

Avalanche Problems

Wind Slabs

New snow will add load to lingering wind slabs that are still reactive to human triggering.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 4

Cornices

Cornices are reported to be large and weak. I wouldn't linger on alpine slopes with overhead hazard nor would I venture to close to ridge edge.

Cornices become weak with daytime heating, so travel early on exposed slopes. >Extra caution needed around cornices with current conditions. >

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 2 - 5

Deep Persistent Slabs

Isolated large avalanches failing on weak snow buried deeply in the snowpack remain a possibility especially given a heavy trigger like a falling cornice.

Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6