Avalanche Forecast

Issued: Jan 1st, 2015 7:13AM

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

pgoddard, Avalanche Canada

Cariboos.

Avalanche danger is expected to rise as new snow overloads a weak snowpack.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Friday

Weather Forecast

Snowfall is expected to become more intense overnight and into Friday (up to 40cm by Friday afternoon). Winds are forecast to become moderate to strong from the SW to NW. Freezing level at valley bottom. Snowfall becomes light on Saturday before a second pulse of snow arrives late on Sunday.

Avalanche Summary

Natural avalanches have been reported up to size 2 where the recent storm snow has been transported into a wind slab. Some of these avalanches have released on or stepped down to the mid-December persistent weak layer of surface hoar and crust.

Snowpack Summary

Snow and wind forecast for Friday will add stress to a snowpack that varies across the region, but is volatile in some places. New snow is expected to hide wind slabs which formed recently in response to strong northerly winds. Storm slabs or wind slabs may overload the persistent weak layer of mid-December surface hoar. This layer is buried under a consolidated slab, anywhere from 15-80 cm deep. Below 2100 m, the buried surface hoar sits on a thick, solid crust and has been acting as a perfect sliding layer. In the worst affected areas, this layer sports well preserved 10-50 mm crystals, especially within a few hundred metres of treeline. A hard rain crust with facets from early November is buried more than a metre down and is currently unreactive. However, triggering from shallow rocky and unsupported terrain remains a concern.

Problems

Persistent Slabs

A buried surface hoar/ crust layer demands respect. It has been easy to trigger, even from a distance. As new snow builds above this weakness, avalanches are expected to become larger and easier to trigger.

Stick to small features with limited consequence and be aware of what is above you at all times.>Avoid steep rollovers at and just below treeline where the surface hoar may be well preserved and sitting on a hard crust.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 6

Storm Slabs

New snow and wind are likely to build storm slabs overtop of existing wind slabs.

Stick to non-avalanche terrain or small features with limited consequence.>The recent snow may now be hiding windslabs that were easily visible before the snow fell.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Jan 2nd, 2015 2:00PM