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Avalanche Forecast

Mar 3rd, 2012–Mar 4th, 2012
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
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: South Columbia.

Confidence

Good

Weather Forecast

Sunday: Moderate to heavy snow. Freezing level 500m, rising to 1100-1400m by afternoon. Strong south-westerly winds.Monday: Moderate to heavy snow. Freezing level falling in the afternoon, reaching valley bottom overnight. Light to moderate north-westerly winds.Tuesday: Light snow. Freezing level valley bottom. Light to moderate westerly winds.

Avalanche Summary

Many avalanches have been triggered remotely (from several hundred metres away) and accidentally by skiers and machinery this week. These avalanches were failing on upper snowpack persistent and storm snow weaknesses, on almost all aspects and elevations. Initial reports on Saturday indicate that a natural avalanche cycle has begun, with avalanches running near full-path and failing on a variety of aspects.

Snowpack Summary

Snow is falling with strong winds and fluctuating temperatures, creating a perfect recipe for new storm slab and wind slab instabilities. This new snow is landing on variable surfaces including surface hoar and facets. Widespread persistent weak layers buried in February have remained touchy all week and are a key concern at all elevations. Storm slabs, wind slabs and sluffs could trigger these deeper weaknesses, creating avalanches which are larger than you expect, given the amount of fresh snow. Large cornices also loom as potential triggers for deep avalanches.

Avalanche Problems

Storm Slabs

Snow is falling with fluctuating temperatures, causing storm slab development. Storm slabs could step down to a persistent weak layer, creating surprisingly large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 7

Wind Slabs

Strong winds are creating widespread wind slabs, even at treeline. Large cornices also threaten many slopes.

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

Elevations: Alpine, Treeline.

Likelihood: Very Likely

Expected Size: 1 - 6

Persistent Slabs

Touchy persistent weak layers, about 1-1.5 metres deep, are tricky to manage. These may be triggered naturally during the storm, or by a light additional load, like a sled or skier, at all elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 7