Avalanche Forecast

Issued: Jan 18th, 2012 9:22AM

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

Avalanche Canada jfloyer, Avalanche Canada

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Thursday: should stay cold and dry, although some areas may experience inversion conditions with warmer temps higher up. Winds will increase slightly but should stay in the moderate range, and will shift back around to the west. Friday: a storm is approaching, which will gradually increase in intensity through the day. Anticipated amounts are 5-10 cm new snow with temperatures rising to around -5C. Friday night will see high snowfall amounts, in the region of 30 cm, as well as a freezing level spike to 1500 m. On Saturday, a further 15-20 cm new snow is anticipated, with freezing levels falling slightly to around 1000 m.

Avalanche Summary

On Wednesday, small (size 1) soft slabs could be skier-triggered in steep terrain. Loose snow avalanches could also be readily triggered.

Snowpack Summary

20-40 cm low density storm snow currently lies on the surface. Moderate winds (first from the SW and then gradually shifting NW then NE) have now had a chance to blow this low density, cold snow around and as a result, fresh wind slabs are prevalent on lee slopes in exposed areas. Below the storm snow lies a rain crust at lower elevations (up to around 1800 m) and old wind slabs/sastrugi in exposed areas at higher elevations. I would be suspicious about the interface between the old layers and the new storm snow. Reports indicate there is not a lot of surface hoar around (likely blown away). However, the cold temperatures likely mean facets will be preserved. Acting in conjunction with a rain crust or a hard wind slab layer, this could set up some touchy slab avalanche conditions in the upper snowpack. Concern for lower snowpack layers has diminished and remains only in shallow snowpack areas. Facets associated with a crust from mid-December and/or sugary facets at the base of the snowpack may still be a concern in shallow areas. Fragile cornices are still looming.

Problems

Wind Slabs

An icon showing Wind Slabs
Shifting winds have set up touchy wind slabs on lee slopes on a variety of aspects in exposed terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Loose Dry

An icon showing Loose Dry
Loose dry snow can sluff easily in steep terrain. In the wrong terrain, it could knock you off your feet, or carry you into a terrain trap.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Valid until: Jan 19th, 2012 8:00AM