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Avalanche Forecast

Archived

Dec 18th, 2023–Dec 19th, 2023

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

Northwest Coastal, Boundary, Stewart, Ningunsaw, Ningunsaw, Ningunsaw.

The potential exists for recent storm snow over surface hoar to step down and trigger larger slabs in sheltered lee terrain. Select conservative terrain and assess how new snow is bonding.

Confidence

Moderate

Avalanche Summary

On Saturday a size 2.5 glide slab avalanche was observed in the alpine. Numerous both loose dry and slab avalanches up-to size 2 had been observed in steep unsupported terrain with a few of them running far in the track. All of the other professional operations in this areas did not observe any new avalanches.

On Wednesday, a large avalanche cycle occurred. Natural and explosive triggered avalanches avalanches, up to size 3, were reported throughout the region.

Snowpack Summary

In the Alpine, recently buried surface hoar is near the surface, with the latest snow redistributed into a soft slab by previous southwesterly winds. The Nov 26th layer is situated down 100 to 200 cm. Below treeline, a trace of new snow overlays small surface hoar. The mid and lower snowpack is dense and well-settled, containing various crust layers. Snowpack depths vary, averaging around 250 cm.

Weather Summary

Monday Night

Mostly cloudy, trace to 5 cm accumulation, ridgetop winds southwest 20 km/h, treeline temperature - 10°C.

Tuesday

Cloudy, 1 to 5 cm accumulation, ridgetop winds south southeast 20 km/h, treeline temperature -8 °C.

Wednesday

Mostly cloudy, 1 to 5 cm accumulation,, ridgetop winds southerly 80 km/h, treeline temperatures -6 °C.

Thursday

Cloudy, 10 to 15 cm accumulation, ridgetop winds south southeast 50 km/h, treeline temperature -2 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
  • Choose relatively conservative lines and watch for clues of instability.

Problems

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.

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.