Avalanche Forecast

Issued: Jan 9th, 2012 3:00PM

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

jfloyer, Avalanche Canada

Sea To Sky.

Summary

Confidence

Good - -1

Weather Forecast

A ridge of high pressure sets up over this region for Tuesday and Wednesday, bringing dry, clear weather. Treeline temperatures will hover around -8 to -10C. Winds should be generally light from the north. On Thursday, clouds will start to build ahead of a relatively weak frontal system, winds will shift round to the west and temperatures will increase to around -2C. Flurries are possible, more likely it will stay dry.

Avalanche Summary

A natural avalanche cycle occurred to size 2 on steep slopes on all aspects in response to the new snow and rain on Sunday and Monday. Reports indicate activity was isolated to the dense new snow. There were no reports of activity stepping down to any of the lower weak layers in the snowpack.

Snowpack Summary

At treeline, snowpack depths are around 260cm.The upper snowpack comprises a series of storm snow layers, which have generally bonded well to each other and are now gaining strength. Rain to approximately 2000 m has left us with a moist surface layer--expect this to freeze into a hard crust as temperatures start to fall. In the alpine, above the elevation where rain fell, significant new wind slabs have developed in response to very strong southwesterly winds. Concern for lower snowpack layers remains only in low snowpack areas. Facets associated with a crust from mid-December and/or sugary facets at the base of the snowpack could be a concern in areas you know to be unusually shallow, or where you can see rocks poking up out of the snow.

Problems

Wind Slabs

Watch for sensitive wind slabs lurking below ridgecrests, behind terrain features and in cross-loaded gullies.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Storm Slabs

Storm slab avalanches occurred in response to new snow and rain on Sunday/Monday. Above the rain line, storm slabs will continue to be reactive for another day or so.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

Primarily a concern in the northern part of the region. Difficult to trigger, but possible from an area with a shallow, rocky snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Jan 10th, 2012 8:00AM