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Archived

Avalanche Forecast

Jan 16th, 2012–Jan 17th, 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
1: Low
The avalanche danger rating below treeline will be low
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Confidence

Poor - Track of incoming weather is uncertain on Wednesday

Weather Forecast

Tuesday: Continued isolated flurries with freezing levels in valley bottoms and strong westerly alpine winds. There is high uncertainty with the weather for Wednesday and Thursday. Some forecast models are calling for moderate snowfall while others are calling for almost none. It all has to do with track of a frontal system that's primarily heading south of the region. If heavy loading from snow or wind does occur, then expect avalanche danger to increase.

Avalanche Summary

Reports from yesterday include isolated Size 1 human triggered wind slab avalanche on a east-northeast facing alpine slope near the ridgecrest, generally sluggish and slow moving. Low density storm snow is sluffing readily in steep terrain with a natural cycle overnight Saturday. In some cases they're entraining considerable mass and reaching up to Size 2.

Snowpack Summary

Snow flurries have 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