Avalanche Forecast

Archived

Dec 11th, 2023–Dec 12th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely.

Regions

Blue River, Premier, Clemina, Esplanade, North Monashee, North Selkirk, West Purcell, Badshot-Battle, Central Selkirk, Goat.

Make conservative terrain choices. Recent storm snow and buried weak layers may be primed for human triggering at treeline and above.

Confidence

Moderate

Avalanche Summary

On Sunday near Revelstoke, numerous human and explosive-triggered size 1 to 2 storm slabs were reported from northeast aspects in the alpine and treeline. In the Esplanades, skiers remote-triggered two persistent slab avalanches (size 1 and size 2) in alpine terrain.

Natural avalanche activity has tapered, but human-triggered avalanches remain likely at higher elevations. Consider the potential for remotely-triggering slopes above and adjacent to you.

Snowpack Summary

The recent 30 to 50 cm of storm snow has likely been redistributed into deeper deposits on north and east-facing slopes at higher elevations. This sits over a rain crust that has been observed up to 1800 to 2200 m throughout this region.

A concerning layer of surface hoar is now buried 60 to 90 cm deep. A widespread natural cycle may have destroyed this layer in steep features but it likely still lingers unaffected features.

The lower snowpack is a mix of rounded and faceted grains. A hard crust may be found near the ground.

Treeline snowpack depths are variable and generally range between 60 and 100 cm. Snowpack tapers rapidly as you move lower in elevation.

Weather Summary

Monday night

Clearing. Alpine wind light and variable. Treeline temperature around -7 C.

Tuesday

Mainly sunny with valley cloud. Alpine wind light from the southwest. Treeline temperature around -2 C.

Wednesday

A mix of sun and cloud. Alpine wind 40 to 90 km/h from the southwest. Treeline temperatures around -2 C with the potential for an above freezing layer to develop in the alpine.

Thursday

Cloudy with snowfall, 5 to 10 cm of accumulation. Alpine wind 15 to 40 km/h from the southwest. Treeline temperature around -5 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Use conservative route selection and resist venturing out into complex terrain.
Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
Stay off recently wind loaded slopes until they have had a chance to stabilize.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.