Avalanche Forecast

Issued: Dec 3rd, 2011 9:33AM

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

Avalanche Canada jlammers, Avalanche Canada

Summary

Confidence

Poor - Freezing levels are uncertain on Monday

Weather Forecast

No precipitation is forecast for sunday, monday or tuesday. Mostly broken cloud is expected with moderate north/northwest winds. Temperatures are uncertain throughout the period. Some models indicate freezing levels remaining at or near surface while others claim a spike to 3000m on monday.Stay tuned for more info.

Avalanche Summary

Widespread size 2 natural activity reported from the region on wednesday. No new observations have been reported. Any observations from the field are welcome. Please send to forecaster@avalanche.ca

Snowpack Summary

Expect to find around 200cm of snow near treeline. In the alpine there's either more or less depending on local wind patterns. I suspect last weekend's storm snow is settling into place and gaining strength. The snow and wind that occurred over the last few days will have created pockets of touchy windslab that will be lingering on lee and cross-loaded features at treeline and in the alpine. Forecast northerly winds may stiffen the current wind slab and/or redistribute surface snow creating new ones. A rain crust that developed on November 27th is about 20-35 cms below the surface (elevation dependant). It`s about 2 cms thick at 1700m and is reportedly 'bullet-proof' closer to valley bottom. Some reactivity has been observed on this layer below treeline.Closer to the ground is the early November surface hoar; somewhere around 50 cm above ground or 150 cm below the surface. It may be difficult to trigger this layer but has a sudden planar characteristic. I also suspect a lingering rain crust down there. Finally, 2 cms of light snow fell on November 2nd burying a layer of surface hoar. It's not an issue at this point, but it's something to keep on your radarIt's still November (just barely), so we only have a teenage snowpack at best: variable, unpredictable, maybe moody. I suggest giving the snowpack a few days to reveal its secrets.

Problems

Wind Slabs

An icon showing Wind Slabs
Expect touchy windslabs in lee or cross-loaded terrain. The nature of this problem may become more complicated with forecast northerly winds. Reactivity may also increase if temperatures rise.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Storm Slabs

An icon showing Storm Slabs
Soft slabs up to 30 cms deep have been observed in open areas below treeline running on the November 27th rain crust. Reactivity may also increase if temperatures rise.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
Probability of triggering has decreased. Where it still exists, this layer may be capable of producing highly destructive, full depth avalanches. Reactivity may also increase if temperatures rise.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Dec 4th, 2011 8:00AM

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