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Avalanche Forecast

Archived

Nov 15th, 2012–Nov 16th, 2012

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

Regions

Little Yoho.

A warm and windy storm may blow through on the weekend, but expect little change in the danger levels until it arrives Saturday afternoon.

Weather Forecast

Little change in the weather on Friday, but expect ridge-top winds to pick up to strong/extreme from the W/SW on Saturday, with freezing levels spiking to 1800m and 5-10cm Saturday night.

Snowpack Summary

A field trip to the Bow Summit area today found an average snowpack of 55-65cm. Generally, 20-25cm of variable soft slabs with pockets of unconsolidated snow overlay the laminated November rain crust, which supported skis but not a person on foot.

Avalanche Summary

No new activity seen in the last 48 hours. Expect a natural cycle to develop on Saturday, especially later in the day, when warm temperatures, strong winds, and new snow combine to create windslabs.

Confidence

Forecast snowfall amounts are uncertain

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.