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Avalanche Forecast

Archived

Dec 22nd, 2017–Dec 23rd, 2017

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

Regions

South Rockies.

Conditions are highly variable. Wind slabs and a buried weak layer warrant a cautious approach to terrain. Read the forecasters' blog here for some great advice!

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

SATURDAY: Dry and sunny, strong northwest winds, temperatures around -17 C.SUNDAY: Dry and sunny with some clouds, moderate northwest winds, temperatures around -17 C.MONDAY: Mix of sun and cloud, light northwest winds, temperatures around -20 C.

Avalanche Summary

Over the past few days, avalanche activity has been reported in the east of the region where higher snow amounts occurred. This includes several large (size 2) explosive-triggered wind slabs on Friday. Smaller slabs have been triggered by skier traffic in steep terrain.

Snowpack Summary

In the southern and eastern parts of this region, up to 100 cm of snow has fallen in recent storms, combined with variable winds. In the Elk Valley, the amount of new snow is more like 40 cm. The new snow has fallen on a variety of surfaces including old crusts, wind-scoured surfaces and, in sheltered terrain at and below treeline, very large feathery surface hoar crystals. The two crusts that were buried near the end of November can be found lower in the snowpack. A third crust from the end of October exists near the base of the snowpack. Recent testing on this crust have not produced significant results.

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.