Avalanche Forecast

Issued: Mar 6th, 2012 9:48AM

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

swerner, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Freezing levels are uncertain on Thursday

Weather Forecast

A frontal system over Northern BC tracks inland tonight/tomorrow, the Northern parts of the region may see light amounts of precipitation Wednesday into Thursday am. Wednesday: Cloudy, with scattered flurries. Ridgetop winds moderate-strong from the NW. Treeline temperatures near -10. Freezing levels valley bottom rising to 8-1300 m by late afternoon. Thursday/Friday: Few flurries in the am. Mix of sun and cloud in the afternoon. Overcast on Friday. Ridgetop winds moderate from the West, getting stronger from the SW through to Friday night. Flurries expected overnight. Freezing levels 12-1200 m both days.

Avalanche Summary

A widespread natural cycle occurred on Monday. Operators have reported naturals from size 1-3, on all aspects and elevations. Numerous skier triggered avalanches also occurred all size 1. I suspect conditions will still remain touchy, and unpredictable.

Snowpack Summary

Over the weekend, 60-100 cm snow has fallen. Strong winds and fluctuating temperatures are creating storm slabs and wind slabs on a widespread basis. Persistent weak layers (surface hoar, facets, crusts) buried in February are the main concern at all elevations and could be easily triggered by storm slabs, wind slabs or sluffs, or with a light additional load (like a sled or skier). Avalanches may be unexpectedly large, given the amount of fresh snow. If the sunshine appears, I'd be weary of south facing slopes affected by solar radiation. Large cornices have formed, and may act as potential triggers on slopes below. They may step down to a persistent weak layer.

Problems

Wind Slabs

Large amounts of available snow and strong winds have created widespread wind slabs, even at treeline. Large cornices may also threaten many slopes.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Storm Slabs

New storm snow and fluctuating temperatures have been the perfect recipe creating storm slab instabilities. Storm slabs can be triggered by light loads (skiers, snowboarders, and sledders) They can be large, and destructive.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 6

Persistent Slabs

Persistent weaknesses in the upper snowpack are unpredictable and tricky to manage. They are becoming more reactive as storm snow overloads them. Be aware of the potential for surprisingly large, wide avalanches at all elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 7

Valid until: Mar 7th, 2012 8:00AM