Avalanche Forecast

Issued: Dec 21st, 2012 9:31AM

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

ghelgeson, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

Saturday: Light S-SE ridge top winds increasing to mod SW overnight.Â Isolated flurries. 1500m temp: -12 Freezing level: SurfaceSunday: Moderate SW ridge top winds. 1500m temp -12. Occasional flurries.Â Freezing Level: SurfaceMonday:Â Light Easterly ridge top winds. Treeline temp -15. No snow.Â Freezing Level: Surface

Avalanche Summary

No new avalanche observations. Observations are welcome, please email us: forecaster@avalanche.ca

Snowpack Summary

The upper snowpack comprises deep amounts of unconsolidated snow in sheltered locations, and soft slabs in open wind exposed terrain. I believe these slabs to be between 20 - 40 cm in depth and are most likely to be found immediately behind ridge crests and lee of mid slope terrain features like ribs. Overall, the top and mid-snowpack is reported to be settling well. Persistent and Deep persistent instabilities (surface hoar and an early November crust, respectively) located in the middle and near the bottom of the snowpack may still be a concern but there's little recent evidence of them. It is important to know that we have very limited observations for this region. Digging down and making your own observations, especially in thinner snowpack areas, remains a good idea to assist safe slope selection. You're looking for weak layers that pop or drop in stability tests.

Problems

Wind Slabs

Wind slabs should slowly diminish in sensitivity this weekend, but I suspect they're still capable of failing and taking you for a ride. Watch for wind slabs immediately below ridge crest and in the lee of mid slope terrain features like ribs.

Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>Use all your senses to avoid wind affected slopes. If you see obvious signs of wind loading, or you feel the snow stiffen under your skis or machine, back off and head to wind sheltered terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 6

Deep Persistent Slabs

Be extra careful in areas where ground roughness is not present to act as anchorage. Smooth ground cover areas include firn on glaciers, grassy slopes and rock slabs.

Avoid thin areas that may propagate to deeper instabilities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 7

Valid until: Dec 22nd, 2012 2:00PM