Avalanche Forecast

Issued: Mar 2nd, 2012 9:42AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs, Wind Slabs and Persistent Slabs.

pgoddard, Avalanche Canada

South Columbia.

Incoming weather systems will have a variable effect across the region. See 'forecast details' for more.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

In general, the weekend’s storm is forecast to hit the northern part of the region (near Revelstoke) most heavily, with progressively less snow as you go south. Freezing levels will climb the highest in the south. Weather will be very variable across the region, so avalanche danger will correspondingly be variable.Saturday: Moderate snow (~15-35cm), with highest amounts in the north and west. Freezing level gradually rising to around 1500m. Strong westerly winds.Sunday: Freezing level continuing to rise, peaking at about 1700m. Moderate precipitation (~15-35mm), with highest amounts in the north and west. Strong westerly winds.Monday: A cold front brings moderate to heavy precipitation with the freezing level dropping to valley bottom overnight as the front departs.

Avalanche Summary

Many avalanches have been triggered remotely (from several hundred metres away) and accidentally by skiers and machinery this week. These avalanches are failing on upper snowpack persistent and storm snow weaknesses, on almost all aspects and elevations. Natural avalanche activity is likely to increase again this weekend with incoming weather.

Snowpack Summary

Snow is falling with strengthening winds and rising temperatures, creating a nice recipe for new storm slab and wind slab instabilities. Widespread persistent weak layers buried in February, which have remained touchy and unpredictable all week, are a key concern at all elevations. Storm slabs, sluffs or a person could easily trigger these deeper weaknesses. Avalanches may be larger than you expect, given the amount of fresh snow. Large cornices also loom as potential triggers for deep avalanches.

Problems

Storm Slabs

Snow is falling with rising temperatures, making storm slab development likely. 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 - 4

Wind Slabs

Strong westerly winds are likely to create widespread new 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 a key concern. 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

Valid until: Mar 3rd, 2012 8:00AM