Avalanche Forecast

Moderate -

Friday night: Increasing cloud, moderate SW wind, treeline temperature around -5 °C.

Saturday: Mostly cloudy, moderate to strong SW wind, treeline high around -5 °C.

Sunday: Snowfall 10-15 cm, moderate to strong SW wind, treeline high around -4 °C.

Monday: Snowfall 5-10 cm, light NW wind, treeline high around -8 °C.

The theme over the past week has been large cornice failures and wind slab avalanches size 2-3 in the alpine. Last Sunday, a snowmobiler accidentally triggered a large wind slab (size 2.5) on a lee alpine slope. The fracture line was up to 1 m deep.

Solar triggered loose dry avalanches were observed in the past week, starting from a point and rapidly entraining mass to as large as size 2.5.

A deep persistent avalanche problem in the North Columbia forecast region has produced large and notable avalanches last weekend, and the southeast corner of the Cariboos appears to have a similar lingering problem. On Saturday, explosives triggered a 2.5 deep persistent avalanche on a NE aspect at 2100 m south of Valemount.

The snow surface is highly wind affected in exposed terrain and wind slabs continue to linger in leeward features. On steep solar aspects and at lower elevations, a melt-freeze crust may be found. In sheltered areas, a new layer of surface hoar is expected to be fairly widespread and some operators reporting it to be as large as 15 mm. 

The upper snowpack contains a few prominent layers but these generally appear to have gone dormant and are not currently creating a problem. A thin crust and a spotty layer of surface hoar may be found down around 20 cm. A layer of facets and small surface hoar from early January is around 60 cm deep and a thick layer of facets from the end of December is around 80-100 cm deep.

The lower snowpack is strong and settled in most parts of the region, except the southernmost part of the region around Blue River where there is a deeply buried crust/facet layer from early December that could be exhibiting similar behavior to the deep persistent slab problem in the neighboring North Columbia region. This layer is most prevalent at below treeline elevations and has been reactive to heavy triggers like smaller wind slab avalanches that step down to this layer. This layer is now considered dormant but could still wake up with storm loading or a major warming event. 

• Carefully evaluate steep lines for wind slabs.
• Wind slabs may be poorly bonded to the underlying crust.
• Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.