Avalanche Forecast

Archived

Dec 13th, 2022–Dec 14th, 2022

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Purcells, Dogtooth, East Purcell.

A spooky buried weak layer is here to stay for the foreseeable future. Conservative decision making is key. Check out our latest blog for advice on how to manage this problem.

Confidence

Moderate

Avalanche Summary

Over the past week, we've had reports of persistent slab avalanches on a buried weak layer. On the weekend, two skier-triggered size 2 avalanches were reported ~40 cm deep at treeline near Golden. Otherwise, persistent slab avalanches throughout the region have been mostly explosive controlled, size 1-2.

In the neighboring central Columbia and west Kootenay regions, where the weak layer is buried deeper, reports of avalanche activity on this layer have been piling up daily. Unfortunately, this is more likely than not a sign of what is to come for the Purcells.

Snowpack Summary

5-10 cm of recent snow sits on a variety of surfaces ranging from hard wind slabs to soft, unconsolidated facets.

A concerning weak layer composed of surface hoar, facets and/or a crust that formed in mid November is now buried 15-40 cm deep. Avalanche activity has been observed on this layer and is expected to continue as the overlying snow takes on more slab character due to settlement, wind and additional snow load.

Alpine snowpack distribution is variable, with depths ranging from 40 to 140 cm.

Weather Summary

Tuesday night

Scattered flurries bringing a trace of snow. Calm to light northerly wind. Alpine low of -12 C.

Wednesday

A mix of sun and cloud. Light northerly wind. Alpine high of -7 C.

Thursday

Sunny. Light northerly wind. Alpine high of -9 C.

Friday

A mix of sun and cloud. Winds switching westerly and building to strong at ridgetop. Alpine high of -11 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Be especially cautious as you transition into wind affected terrain.
Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.

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.