Avalanche Forecast

Thursday night: Cloudy with isolated flurries and a trace of new snow. Light northwest winds.

Friday: Mainly cloudy with light flurries bringing a trace of new snow before increasing overnight. Light southwest winds. Alpine high temperatures around -10.

Saturday: Becoming sunny. up to 10 cm of new snow from overnight. Light northeast winds shifting northwest. Alpine high temperatures around -10.

Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Moderate to strong west winds. Alpine high temperatures around -9.

Reports from Wednesday included three more very large (size 3) persistent slab avalanches in the southeastern part of the region, not far from Allan Creek. These avalanches failed naturally on the 150 cm-deep late December surface hoar described in our snowpack summary. They occurred on north and east aspects at around 2300 metres. The debris flow from one was destructive enough to run up an opposing slope after crossing valley bottom.

Numerous small (size 1) storm slabs were triggered with ski cutting on Wednesday as well. The crown fractures of these 10-20 cm-deep releases were limited to the depth of our most recent snowfall but they did manage to entrain loose snow to the depth of our new crust.

With continuous stormy weather over the past week, operators have reported several very large (size 2.5-4) avalanches breaking on deeper weak layers. Avalanches in surface layers or cornice fall may have the potential to step down to this layer.

During the weekend storm, numerous small to very large (size 1.5-3.5) avalanches released naturally in the storm snow. These avalanches primarily occurred on leeward aspects at treeline and alpine elevations.

20-60 cm of snow from the early part of the week overlies previously wind-affected snow at higher elevations, with diminished depths of about 20-30 cm above a widespread melt-freeze or rain crust up to about 1700 metres. This recent snow has shown variable reactivity, with reports showing a mix of soft wind slabs around treeline, sluffing of low density snow in steep terrain, and poor bonding with the buried crust where it exists.

The mid and lower snowpack are generally well settled, however an aging weak layer of surface hoar from late December, currently buried 70 to 150 cm deep, has shown surprisingly long-lived instability on slopes between 1700-2400 m (above the crust elevation and below the most wind-affected elevations), warranting increased caution around steeper slopes in this elevation band, particularly in the southern half of the region.

• Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
• Seek out sheltered terrain where new snow hasn't been wind-affected.
• Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.