Archived

Avalanche Forecast

Mar 4th, 2016–Mar 5th, 2016

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

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.

New snowfall amounts are expected to vary greatly across the region. Pay close attention to how much new snow fell in your riding area as this will affect your local Avalanche Danger.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

On Saturday expect a mix of sun and cloud, light flurries and moderate/variable winds. On Sunday the region may see an additional 3-8cm of new snow and moderate easterly winds. On Monday, expect a mix of sun and cloud with light winds. Freezing levels should hover around 1300m for the forecast period.

Avalanche Summary

On Wednesday, a size 3 deep persistent slab avalanche was accidentally triggered by a skier in alpine terrain in the north of the region. To our knowledge, nobody was injured in the incident. The slab, which ran on basal facets, was up to 200cm deep, 200m wide and 500m long. There have been a handful of recent similar avalanches triggered on basal facets in the mountains north of Kispiox. Although observations have been limited, I suspect new snow and wind on Wednesday, Thursday and Friday also promoted a round of wind slab activity at treeline and in the alpine.

Snowpack Summary

On Thursday and Thursday night, 3-15cm of new snow fell with the highest accumulations occurring in the southwest of the region. Strong winds shifted the new snow into new wind slabs at treeline and in the alpine adding to an ongoing wind slab problem. A layer of surface hoar from early January can be found in isolated locations between 60 and 140cm 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.

Avalanche Problems

Wind Slabs

New snow and wind has created fresh wind slabs at treeline and in the alpine. Watch for triggering in the lee of ridgecrests and terrain breaks.

Be aware of the potential for wide propagations due to the presence of hard windslabs.>The recent snow may now be hiding windslabs that were easily visible before the snow fell.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Deep Persistent Slabs

A layer of facets close to the ground remains a low probability/high consequence concern for most of the region. However, in the north it is more active and has been responsible for several recent large natural and skier triggered avalanches.

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

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 3 - 5