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Avalanche Forecast

Feb 11th, 2013–Feb 12th, 2013
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: Purcells.

Danger could be slightly higher in the alpine on Wednesday if we see snow accumulations of 10 cm or more with the approaching system.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Tuesday: A frontal system approaches the coast and moves across the province. Flurries are expected during the day (2-3 cm) and moderate snow in the evening and overnight (~5 cm). Winds increase to strong from the southwest later in the afternoon. The freezing level is around 1200 m. Wednesday: Possible flurries early then a mix of sun and cloud. The freezing level drops to 500 m. Winds are light from the northwest. Thursday: A mix of sun and cloud. The freezing level is near valley bottom. Winds are light from the west.

Avalanche Summary

A couple new size 2.5 slab avalanches were triggered by explosive controlled cornice failures. The cornices triggered slabs on a steep north aspects that were 35-70 cm deep. Other than that, avalanche activity was limited to small loose sluffing in steep sun-exposed terrain.

Snowpack Summary

The snow surface consists of new wind slab in exposed alpine terrain, a sun crust on solar aspects, and surface hoar and/or facets on shady slopes. The recent storm slab continues to settle over old interfaces comprising of surface hoar, crusts and facets down 30-50 cm. However, areas that have buried surface hoar seem to be most touchy. Continued freezing temperatures overnight have helped to strengthen the snowpack at lower elevations.The mid-pack is generally well settled and the average snowpack depth at treeline elevations is near 130. Cornices have grown and may threaten slopes below.

Avalanche Problems

Wind Slabs

Wind slabs may be reactive to light loads like skiers or snowmobiles. Areas of concern are steep open slopes immediately lee of ridges and terrain features.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Persistent Slabs

The recent storm snow continues to settle into a cohesive slab above weak layers and variable old surfaces that comprise of buried wind slabs, surface hoar, and crusts. These weak layers exist 30-50 cm below the surface. They can be tricky to manage.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 5