Avalanche Forecast

Issued: Jan 12th, 2012 9:10AM

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

Avalanche Canada jfloyer, Avalanche Canada

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Saturday

Weather Forecast

Friday should be another dry day with some cloud. A strong inversion between around 1400 and 2000m will initially be present, giving way to cooler temperatures in the afternoon. Winds will be moderate from the west. On Saturday, around 10 cm of snow is expected with gusty southwesterly winds and freezing levels most likely at valley bottom. On Sunday, strong, gusty winds will likely shift from SW to NW and temperatures will be cold. Flurries or light snowfall is the most likely scenario, moderate snowfall possible.

Avalanche Summary

Explosive control produced avalanches uo to size 3 in very steep north aspect terrain along the Coquihalla on Thursday, with some avalanches scouring to ground. This indicates to me that with the right load (eg. a cornice release or airborne sledders) hitting the right bit of terrain (steep, thin) you can still get a dangerous avalanche to release in this region.

Snowpack Summary

Warm daytime temperatures and cool overnight temperatures have created a hard, crusty surface layer in many places, even up into the alpine. Surface hoar is growing on this surface, reportedly 3-5mm at this time. While it's on the surface, it obviously doesn't cause us too many problems, but if it is buried with snow, it has the potential to become our next touchy weak layer. The upper snowpack comprises a series of storm snow layers, which have generally bonded well to each other and are now gaining strength. Fresh new wind slabs have developed in response to strong southwesterly winds. Winds also blew from the north for a while, and there are reports of areas where reverse loading is an issue. Concern for lower snowpack layers remains only in low snowpack areas, such as the east side of the Duffy or in the Chilcotins. If you're a keen follower of the bulletins you'll notice I've taken the persistent weak layer problem out of the primary problems for this region. It really seems as though this layer has been sufficiently buried for long enough that it no longer pose a threat in the vast majority of locations. If you're riding steep aggressive lines in open terrain in one of the shallower snowpack areas mentioned above, I would still be concerned with deeply buried persistent weak layers. The layers of concern are surface hoar and/or facets associated with a crust from mid-December and/or sugary facets at the base of the snowpack, particularly in sheltered treeline areas that are unusually shallow or on slopes where you can see rocks poking up out of the snow.

Problems

Wind Slabs

An icon showing Wind Slabs
Watch for wind slabs in the immediate lee of ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Jan 13th, 2012 8:00AM