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Avalanche Forecast

Archived

Dec 10th, 2023–Dec 11th, 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

Purcells, Dogtooth, East Purcell.

Avoid thin and rocky start zones, weak layers in the mid and lower snowpack are showing reactivity to human triggers.

Confidence

Moderate

Avalanche Summary

Explosive control yesterday produced slab avalanches; one stepped down to the weak basal facets at the base of the snowpack.

A remotely triggered slab was reported on a NE facing slope at 2300m in a shallow rocky area, also failing on the basal facets.

Snowpack Summary

The recent 30 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 1900 m near Golden and 2200 m near Invermere.

A concerning layer of surface hoar is now buried 40-70 cm deep. A widespread natural cycle may have destroyed this layer in steep features but it likely still lingers unaffected features.

The middle and base of the snowpack holds large, weak snow crystals. 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

Sunday Night

Partly cloudy, trace amounts of snow. Southwest winds 10-20 km/h. Freezing levels drop back to valley bottom.

Monday

Mostly cloudy, no snowfall expected. Treeline temperatures around -7 °C. Light and variable wind.

Tuesday

Clearing skies with no snowfall expected. Southerly winds, 10-20 km/h. Treeline temperatures around -10 °C

Wednesday

Partly cloudy with no snowfall expected. Southerly winds increase, around 40 km/h. Treeline temperatures around -10 °C

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Make conservative terrain choices and avoid overhead hazard.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
  • 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.