Avalanche Forecast

Issued: Jan 16th, 2012 9:47AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs and Loose Dry.

Avalanche Canada ccampbell, Avalanche Canada

Summary

Confidence

Poor - Track of incoming weather is uncertain on Wednesday

Weather Forecast

Tuesday: Continued light flurries with treeline temperatures in the minus teens and strong westerly alpine winds.There is high uncertainty with the weather for Wednesday and into Thursday. Some forecast models are calling for light to moderate snowfall with associated winds, while others are calling for dry and mostly clear. It all has to do with the 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 a few reluctant slope cut Size 1 soft slabs on steep, convex, unsupported features. They had limited propagation and did not run far. Slope cuts on steep north facing convexities also triggered isolated stubborn buried wind slabs down 60cm with avalanches up to Size 1. 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

20-40 cm of low density new snow is being redistributed by westerly winds forming weak wind slabs and cornice tabs on lee aspects, but remains fluffy and cohesionless in most sheltered areas. This new snow now sits on a variety of surfaces (facets, surface hoar in sheltered areas, soft slabs, hard slabs, wind crust, and a melt-freeze crust below treeline), and currently seems to bonding poorest to underlying crusts. Although still well preserved in isolated areas and producing hard but sudden snowpack test results, avalanche professionals are gaining confidence in the mid-December persistent weakness, now down 110-190cm. The probability is very low (it would take large triggers in the perfect spot) but the consequences would be very high.

Problems

Wind Slabs

An icon showing Wind Slabs
New wind slabs are lurking below ridgecrests, behind terrain features and in cross-loaded gullies.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Loose Dry

An icon showing Loose Dry
Up to 40 cm of very light new snow sluffing easily in steep, unsupported sheltered terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Jan 17th, 2012 8:00AM