Avalanche Forecast

Issued: Jan 31st, 2013 9:04AM

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

triley, Avalanche Canada

South Columbia.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

Overnight and Friday: 5-8 cms expected tonight combined with strong Northwest winds and alpine temperatures about -8.0. Snow ending by morning, becoming high overcast with freezing level rising to about 1300 metres and light Northwest winds.Saturday:Mostly sunny with light West winds. Valley cloud is expected in the main large valleys. Above freezing temperatures are expected in the alpine up to about 2500 metres.Sunday: The next Pacific disturbance is expected to move into the interior from the coast. Temperatures should drop below freezing at all elevations before the system arrives.

Avalanche Summary

There was one skier accidental avalanche size 2.0 that released below treeline on a steep East facing roll, the slab was about 55 cms deep and released on a weak layer of surface hoar (probably Jan23rd). Natural sluffing from steep terrain up to size 1.5. Wind slab avalanches skier controlled up to size 1.5 on East aspects. A few natural slab avalanches releasing in the storm snow down about 60 cms.

Snowpack Summary

Approximately 40 to 60 cm of recent storm snow overlies a weak layer comprising of surface hoar in shady locations, facets at higher elevations and a sun crust on solar aspects. The recent new snow sitting above this interface has been slowly consolidating from fresh powder into a more cohesive slab. A mid-pack surface hoar layer buried in early January is down around 90 cm, and is best preserved below approximately 1700 m. A freezing rain crust has been reported near the surface (it may now be buried by light snow) in the Monashees, particularly in areas close to Mabel Lake.

Problems

Wind Slabs

Northwest winds are expected to develop wind slabs in the alpine and at treeline in the lee of terrain features. There is a lot of loose dry snow available for transport.

Be cautious as you transition into wind affected terrain.>Stay well to the windward side of corniced ridges.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

40-60 cms of storm snow is sitting above a mix of hard old surfaces and areas of soft facetted snow. Some areas may have a weak layer between the old surface and the recent storm snow.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Feb 1st, 2013 2:00PM