Archived

Avalanche Forecast

Mar 10th, 2016–Mar 11th, 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.

Caution is required in exposed wind-affected terrain on Friday.

Confidence

Low - Due to the number of field observations

Weather Forecast

FRIDAY: Cloudy with sunny breaks and a light snow in the afternoon (5 cm). The freezing level is around 800 m and winds are moderate to strong from the SE. SATURDAY: Cloudy with sunny breaks and a chance of flurries. The freezing level is around 900-1200 m and winds are light from the SE. SUNDAY: A mix of sun and cloud. The freezing level is near 1000-1200 m and winds are light.

Avalanche Summary

A few natural wind slabs up to size 2.5 were observed in steep wind-loaded alpine terrain on Wednesday. There was also a large cornice fall that did not trigger a slab on the slope below. 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.

Snowpack Summary

Roughly 20-40 cm of snow has fallen in the past week, with the highest accumulations occurring in the southwest of the region. Strong ridgetop winds have shifted the new snow into hard or soft wind slabs in exposed terrain, adding to an ongoing wind slab problem. A 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.

Avalanche Problems

Wind Slabs

New snow combined with moderate winds have created fresh wind slabs in lee terrain near ridge crests and terrain breaks. Older hard wind slabs may also be lurking below the surface.

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

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Deep Persistent Slabs

Isolated large avalanches failing on weak snow at the base of the snowpack remain a possibility. This is a greater concern during sunny breaks or with a heavy trigger like a falling cornice.

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: Unlikely - Possible

Expected Size: 3 - 6