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Avalanche Forecast

Archived

Dec 6th, 2022–Dec 7th, 2022

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

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

Despite the cold and snowy look outside, not much new snow has actually fallen. 2-5 cm over the past 24 hours with the deepest amounts near Banff. Wednesday will be windy (and cold), so expect drifting to create small, easily triggered soft slabs and dry loose avalanches. Climbers prepare for spindrift and watch for sluff volume in the gullies.

Confidence

Moderate

Avalanche Summary

No new avalanches were observed or reported today, but field observations were minimal with the obscured sky.

Snowpack Summary

Here is an image of the typical snowpack in the Rockies today; 81 cm snowpack at treeline at Crowfoot Glades. Note the 1 cm of low-density new snow on the surface, then about a 20-30 cm slab overlying the Nov 22 interface, below which facets and weak snow grains exist to ground. This snowpack is generally weak and will not handle much extra load.

Weather Summary

The cold, NW flow persists as a ridge of high pressure dominates BC and a low-pressure system sends cold, moist air down the east side of the mountains. The story for the next 24 hours is the wind, which will transport snow. Expect a windy day on Wednesday with gusts reaching 80 km/hr from the west, trace amounts of snow and continued cold temperatures.

More details can be found in the Mountain Weather Forecast.

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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

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.