Avalanche Forecast

Issued: Dec 13th, 2011 8:58AM

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

mpeter, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Wednesday: A weak ridge builds giving a dry day with some lingering cloud. Light westerly winds and temperatures to -8 with a chance of flurries overnight. Thursday: Flurries remain a possibility early in the day, but will likely dry out by afternoon. Continued westerly winds and temperatures reaching -5. Friday: Unsettled skies with more light winds and temps to -5.

Avalanche Summary

No new avalanches.

Snowpack Summary

Up to 20cm of new snow has fallen since the 10th of December. This overlies surface hoar, surface facets, old windslabs and sun crusts (on steep south through west aspects). Winds have been sporadic in this period, with some strong northerlies intermingled with the more dominant light to moderate westerlies. There are isolated new soft slabs in immediate lee locations and some surface sluffing in more protected areas where the surface hoar is more prominent. Moving forward, the avalanche danger will increase as the load increases (either by new snow or wind). Be locally aware of changes and if obvious signs of instability are present (cracking, whumphing, recent activity on adjacent slopes) or rapid loading is taking place (heavy snowfall or strong winds) then scale down your terrain choices accordingly.Deeper in the snowpack there is a rain crust buried between 20-35cm. This crust extends as high as 2200m and some faceting (weakening) has been observed around the crust. Deeper still, the early November surface hoar remains a layer of concern. Buried 100-150cm it is unlikely to trigger, but consequences of triggering would be a large (up to size 3.0) destructive avalanche.

Problems

Wind Slabs

Old windslabs still lurk in lee locations at ridgecrest in the alpine. Be aware of the new snow hiding these old slabs or forming into new soft slabs with the moderate winds.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Dry

The new snow sluffs easily. Minimal hazard at this time, but something to keep in the back of your mind as the load increases.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

Low probability/high consequence situation due to the highly variable snow depths. There is a chance of triggering a deeper instability from a shallow area like around rocks, clumps of small trees or convexities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 14th, 2011 8:00AM