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Archived

Avalanche Forecast

Jan 17th, 2012–Jan 19th, 2012
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
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Kootenay Boundary.

Confidence

Fair - Track of incoming weather is uncertain on Wednesday

Weather Forecast

A strong northwesterly flow will direct most of the precipitation associated with the incoming storm on Wednesday south of the border, meaning this region will either stay dry or have light snowfall of up to 5 cm. Winds will be light from the west during the day on Wednesday, picking up to moderate to strong overnight. Treeline temperatures will be cold-around -20C. On Thursday, the region should stay mostly dry and cold, although freezing levels may start to rise by the end of the day. On Friday afternoon, a punchy frontal system hits the region, bringing moderate snowfall and strong southwesterly winds.

Avalanche Summary

Sluffing in steep terrain was reported on Tuesday. On Monday, an isolated Size 1 human triggered wind slab avalanche occurred on a east-northeast facing alpine slope near the ridgecrest, reported to be sluggish and slow moving.

Snowpack Summary

Light snow has maintained a fresh snow supply for wind slab development and cornice growth,but remains fluffy and cohesionless in most sheltered areas.Surface hoar and/or faceted snow, with an associated crust making it especially touchy on sun-exposed slopes, was buried last week and is now down 15-25cm. Below that a thin melt/freeze crust buried early-January can be found as high as 1900m, and some areas are reporting surface hoar . The mid-December surface hoar/facet persistent weakness, now down 50-120cm, remains a concern with heavy triggers in thin slab areas. Basal facets remain concern in shallow snowpack areas especially with heavy triggers in thin spots, and weaknesses in the slab above create the potential for step-down avalanches.

Avalanche Problems

Wind Slabs

Fresh weak wind slabs are lurking below ridgecrests, behind terrain features and in cross-loaded gullies.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Persistent Slabs

Weak surface hoar is primarily a concern on big unsupported sheltered glades on east through north aspects. Basal depth hoar and facets are a concern on slopes with shallow and variable snowpack depths, especially near ridges and summits.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5